Hi all,

I know crossposting isn't the way to do things, but as I didn't get any response to my questions in the Class society subforum, so I thought, maybe more people in this subforum can answer these.

Sorry for crossposting!

I am still puzzled with the germanische lloyd rules. I am designing a steel 40 ft sailing yacht, and right now I am working on the framing.

I have decided to use transverse frames with a spacing of 400 mm, and longitudinal stringers with a spacing between 250 and 350 mm (max is on maximum beam, becoming closer to the aft and fore.

Using the formulas in the rules (GL for vessels <24m) I get the following (for the first frame)
Longitudinals: a section modulus of 2.39 cm^3 wich would lead to a flatbar 40x8 or 60x5 (mm)
Transverse webframe: a section modulus of 3.1 cm^3 which could be achieved with a L of 60 x 40 x 4. (mm)

I find the stringers extremely large sized compared to the webframes. When I would make the slots for the stringers in the webframes, I would nearly have to cut them through.. bending the stringers in a fair way will become rather difficult I think.

Can anybody tell me if these scantlings are realistic? I don't want to use an L or T for the stringers.

Or is it with GL that you can either use transverse of longitudinal framing? And when using longitudinal framing, the sectionmodulus is calculated without taking the transverse frames into account?

Or did I misinterpret the unsupported lenght? I used lmin in the formula in table 1.43 (page 1-80). In my case the real unsupported length = 0,4 m and lmin = 0,815m more than twice the real length. The rules don't make clear if I should use lmin or the real unsupported length, so I used lmin to be safe.

For the webframes I used the formula in table 1.44 (page 1-80). Beside this formula there is also a formula in table 1.42 to calculate the section modulus of transverse frames.

I just can't figure out if I use the right formula or not. Can anyone help me with this?

Grtz,
Arvy

Have a look at Dave Gerr's book Elements of Boat Strength. There's some scantlings in there that should bring you closer to the real requirements of a 12m vessel. There are also some dusty old volumes from the American Bureau of Shipping that they don't publish anymore. You might be able to lay your hands on a copy of the appropriate one.

Hiya,

I did already look at the Dave Gerr book, it is an ok book I think, but I have a problem with his framespacing. In my case Dave Gerr suggest that one should use 325 mm and this is something that I really don't want. I would like to use 400 mm. But I think I have figured it out already :D

Still thanks for the reply!

Grtz,
Arvy

I have been building origami steel boats with no transverse frames since 1980 with no problems. Over 200 of my designs have been built, and have crossed most oceans, including the NW passage and several circumnavigations.
Using shape and the structural continuety of steel lets you drastically reduce the need for framing . I've reduced the time to tack together a shell( hull , decks, cabin, wheelhouse, keel, cockpit,) to less than 100 hours for a 36 footer. My book is a guide to the proccess.
Too much steel boat design is a direct copy of wooden boatbuilding methods, which do nothing to take full advantage of the properties of steel. Many of the stuctural bits and pieces in traditional steel boatbuilding are structuraly redundant.
They refuse to recognize the phenomenally strong fully welded longitudinal bulkheads that decks , chines, keels, tank tops, etc consitute, and what they contribute to the structural strength of a steel boat, making transverse frames structurally redundant, in boats under 50 ft.
Brent Swain

Hi Brent,

Thanks for your reply. I haven't looked into this building method, but to me it sounds a bit scary, but this is probably a lack of knowledge. You mentioned you have written a book about the subject, could you tell me the title of it?

I just try to follow the rules by the class societies so that I am certain that in the case I need to have the vessel classed that it will get classed. How do the origami steel boats get classed by the societies as they don't follow their rules?

Grtz,
Arvy

Gerr , having stated in a recent article in Sail Magazine, that all steel boats will lose a given amount of hull thickness every year ,regardless of how well they are painted, has a serious credibility problem.
Brent

My book is called "Origami Metal Boatbuilding a Heretics Guide"
I sell it by mail order .
Over 200 of my origami designs have been built ,and they have done everything from circumnavigations to a single season passage thru the NW passage . They have survived everything from 16 days pounding on the west coast of Baja in 12 ft swells to pounding across 300 ft of Fijian coral reef ,to a collision with a freighter in Gibralter, to hurricanes , with no structural dammage. Their structural integrity has been well proven many times over , beyond all reasonable doubt. It is simply a matter of time before origami methods become the standard way of building small caft out of metal, altho dinosaur methods will still prevail amoung a few holdouts.
Brent
brentswain38@yahoo.ca

Hi Brent,

I just try to follow the rules by the class societies so that I am certain that in the case I need to have the vessel classed that it will get classed. How do the origami steel boats get classed by the societies as they don't follow their rules?

Grtz,
Arvy

There's no need in classing a 40 ft boat, but if you want to charter with it you might need a Hull Certificate. This is a statement that the construction was approved and build in accordance with a Class societies rules.

As Class societies make these rules themselves, they can also dicide to accept alternative arrangements and calculation methodes.

I hope while computing the Z value for your stringer, you are taking into account the attached plating. You are supposed to compute the section modulus with attached plating of half frame spacing extending each side, if I remember correctly.
That should give you a much more realistic size of stringer.

Hi Bijit,

I am taking the attached plate into account, I have sent German Lloyds an email to ask them this as it wasn't immediately clear. They sent me an other part of the rules where this was stated. (it is half the frame spacing on each side of the stringer).

After applying this I have a much more realistic value (which is somewhere near what I am remembering from the past).

if you visit my gallery , you will see a 40 foot sailboat with transverse frames. built to and under Lloyds, there are no stringers and the frames are at 400
Brent stop knocking yourself out, you beat the same ole drum over and over In many ways I agree BUT certification bodys are a whole lot smarter than you or I
Most of us want to create a thing of beauty and test our skills, I bet you 5000 bucks you could NOT build the old way, can you wheel stretch, form? from your posts I doubt, but you are entiteled to expand upon your views, however dont try ram em down peoples throats eh, Have bonjour mon ami, I like your Alpha male, style:))

Hi Lazeyjack,

Nice pictures you have in your gallery. Was the m40 built to german lloyds or lloyds? I would like to use only transverse frames at 400 framespacing too, but somehow I get such a large scantlings that I don't quite trust them. Maybe I should recalculate them. Right now I am working on longitudinal framing and webframes at 800mm, but I would like 400 better. Well, I will do a quick recalc.

Hi Lazeyjack,

Nice pictures you have in your gallery. Was the m40 built to german lloyds or lloyds? I would like to use only transverse frames at 400 framespacing too, but somehow I get such a large scantlings that I don't quite trust them. Maybe I should recalculate them. Right now I am working on longitudinal
framing and webframes at 800mm, but I would like 400 better. Well, I will do a quick recalc.

lloyds, deep floors fully welded 6mm plate, from my memory 60x40x6 t section, overlap your sections 2.5 times into floor, folding floors for flange is a real time saver i am not a navel arch. I do things from experience and they seem to pass plan approval, so if you are working with cut frames I spose you sizes are going to go UP

Origami boats would not pass any class survey!

Friends had charter boats built to Canada Shipping Act certification using origami methods, no transverse frames. The Canadian government inspectors , when they were told that they were origami boats said "We are familiar with the method and have no problem with it." The boats passed with flying colours.
I think the survival of my boats for 16 days of pounding in 8 ft Baja surf , a single season passage thru the NW passage, a pounding across 300 yards of Fijian coral reef, a collision with a freighter in Gibralter , etc etc, all without serious damage, are far more relevant than the approval of a desk bound bureaucrat who has never sailed anywhere, never owned and maintained a steel boat for any serious length of time, or never got his hands dirty building one.
Transverse frames greatly increase the chances of a boat being holed on sharp rocks . They are a net liability in boats under 50 feet. When a BC ferry grounded east of Bella Bella ,the only holes were right next to the frames.
Lloyds only approves stainless for keel bolts , which are guaranteed to corode badly in such an environment. I challenge anyone with a Lloyds or any other approved wood or fibreglas sailing craft to a demolition derby against one of my unapproved origami boats. So much for Lloyds, etc.
I built my first boat using old fashioned dinosaur methods , frames set up on a jig , stringers laid along them , then plated. What a total waste of time and effort. Thankfully I had enough steel fabricating experience to relise what a waste of time it was, and was niether masochistic enough to continue this foolishness, nor sadistic enough to impose such slavery on others wanting steel boats .
Brent

Friends had charter boats built to Canada Shipping Act certification using origami methods, no transverse frames. The Canadian government inspectors , when they were told that they were origami boats said "We are familiar with the method and have no problem with it." The boats passed with flying colours.
I think the survival of my boats in extreme conitions, are far more relevant than the approval of a desk bound bureaucrat who has never sailed anywhere, never owned and maintained a steel boat for any serious length of time, or never got his hands dirty building one.
Transverse frames greatly increase the chances of a boat being holed on sharp rocks . They are a net liability in boats under 50 feet. When a BC ferry grounded east of Bella Bella ,the only holes were right next to the frames.
Lloyds only approves stainless for keel bolts , which are guaranteed to corode badly in such an environment. I challenge anyone with a Lloyds or any other approved wood or fibreglas sailing craft to a demolition derby against one of my unapproved origami boats. So much for Lloyds, etc.
I built my first boat using old fashioned dinosaur methods , frames set up on a jig , stringers laid along them , then plated. What a total waste of time and effort. Thankfully I had enough steel fabricating experience to relise what a waste of time it was, and was niether masochistic enough to continue this foolishness, nor sadistic enough to impose such slavery on others wanting steel boats .
A friend built a Laurent Giles custom steel design. The transverse framing was totaly ludicrous, the structural equivalent of putting 12 by 24 inch frames every two feet in a 45 foot wooden boat. I suggested he cut a lot of it out , which he did with no negative consequences, and a huge increase in interior volume.
The comments being made here suggest a similar totally ludicrous type of interior framing.
I once hitched a ride with a guy who had built the framework of a Roberts Spray. When he calculated the amount of work fitting and welding the plating on, he put the finished framework on a trailer, towed it to the dump, took the plates off the trailer , left it here and drove home . He said it was one of the wisest moves he ever made.
I once saw a design for a tahiti Ketch which called for 4,000 lbs of framing and 1/8th inch hull plate. That is the same weight as 3/8th inch plate and no framing. When you are pounding on a rocky lee shore , plating thickness is far more usefull than 4,000 lbs of framing.
I was once offered a job plating such a tahiti ketch famework.I told the owner that I could build a finished hull in a fraction the time it would take to plate his project and he would have a far better boat in the end. You couldn't pay me enough to get me to waste time on such futile foolishness.
Brent

Brent

..........Transverse frames greatly increase the chances of a boat being holed on sharp rocks . They are a net liability in boats under 50 feet. When a BC ferry grounded east of Bella Bella ,the only holes were right next to the frames.


Ships have very thin plating relative to their displacement and this is not an applicable argument to lighter vessels . Framing can limit the extent of damage considerably in smaller vessels.

..........Lloyds only approves stainless for keel bolts

Not quite right. They do approve other materials. I agree though; generally stainless is a poor choice as a keel bolt unless massively over engineered or regularly replaced.

..........I built my first boat using old fashioned dinosaur methods , frames set up on a jig , stringers laid along them , then plated. What a total waste of time and effort. . .

Why? was the boat a complete dog? If not and it sailed well and is still around then it wasn't a waste surely ?


The construction of the hull is a relatively small proportion of the construction time overall. A well built traditional framed hull can be very durable and strong provided some rules are followed by the builder ( and a good designer).
Framing first is neither a dinosaur method nor a foolish one, just another proven way of doing things. If the method works it is definitely not a waste of time or effort in the long run. Particularly if you end up with a more desirable hull-form with attributes not feasible in a 'Brent' type origami boat.

..........When you are pounding on a rocky lee shore , plating thickness is far more useful than ...framing. .

They are not mutually exclusive, you can have both framing and thicker bottom plate. The principal failure mode of the plating is buckling and framing stops the buckling which allows the panel to stretch and absorb a lot more energy and limiting damage.

..........
I was once offered a job plating …a tahiti ketch famework.I told the owner that I could build a finished hull in a fraction the time it would take to plate his project………..get me to waste time on such futile foolishness.


I would have thought that if we limit this to chined boats that once the framing is finished the plating can proceed quickly and easily without lofting, using a simple transferred pattern.

When compared with the very accurate loft and fit-up required for an origami hull, if the frame is completed the hard work is done already.
I’d also note that bar frames for smaller steel chined vessels can be fabricated easily and quickly by a relative novice.

European scantling societies are not overly conservative. When they moved work boats scantlings to leisure craft they went too far at times, some scantlings were deficient in earlier revisions and had to be increased. In such ways the rules have evolved into sensible guides that produce strong and functional vessels. You might even find that the latest ISO GL and DNV even allow for the type of designs you have perfected to your techniques.

They may not be the enemies you imagine since Dutch yards have been aware of these techniques for many decades and have produced many smaller craft to this principle. I've seen barges built in dutch yards with a very similar technique too.

cheers

Frames don't limit dammage on small craft, they increase it. One of my 36 footers hit a sharp rock doing hull speed. It bounced off, undammaged . If it had frames the steel would have had something to stretch against and would have been holed at each frame. Aluminium river boats avoid having transverse frames against the hull skin for this reason.
Had the stringers been set on the frames in the BC ferry , instead of notched into them , the plating would have been creased the full length without holing. A friend, starting one of my 36 footers , got the job of diving on that ferry. He was leery of his boat having no frames ,until he saw the dammage . The ferry was only holed at the hard spots made by the frames. Frames against the hull plate drastically increase the likelihood of a boat being holed on sharp rocks . Without transverse frames it simply bounces back.It is far easier to dent or hole hull plating if you hit it next to a frame, than it is hitting it where there are no frames.
The framing I used on my first steel boat served absolutely no useful function, just made the project far more labour intensive, and heavier. Thus they were a total waste of time, time which could have better been spent using the boat for what a cruising boat is for, cruising.
If you invent many ways to make a boatbuilding project far more time consuming and labour intensive, and these self made hinderances don't change the way a boat looks or sails , does that automatically mean they are useful? Only if the enjoyment of building the boat is the the only reason for it's existence, or maximising the number of man hours you can justify charging a client. Perhaps this is a major source of objection to my efforts to bring ownership of good steel boats within the reach of the not so rich. I'm sure livery stable owners once had similar objections to those new fangled horseless carriages.
I have pulled together 36 foot hulls in three days or less, something you are extremely unlikely to accomplish in a backyard built framed boat.
Attaching plate and stringers to frames before welding is a major source of distortion, which is non existent in frameless hulls, and common on framed ones. The less you do to a piece of plate , the fairer it will remain. Thus simplifying the building proccess is a good way to increase the odds of a hull remaining fair.Weld shrinkage only improves the shape and fairness of origami hulls.
As for Dutch technology, I've sent quite a few books and sets of plans to Holland, thus introducing advanced Canadian technology to them.
When a sharp rock hits between frames, only hull plate thickness will prevent holing. Frames only help if you are so naive as to assume sharp rocks will only hit directly on a frame. When they hit right next to one , the likelihood of a hole being punched in goes up drastically.
It would have taken a lot longer than three days to plate that tahiti ketch and you would have wound up with a massive amount of totally useless redundant scrap metal weighing her down, as well as making the painting exponentially more labour intensive and critical.The amont of welding and grinding that remaind to be done would have been exponentialy greater.
The only welds on a 36 ft origami hull are the centrline, two 14 ft chines amidships, four 6 ft seams on the bottom, two 5 ft seams on the bottom, bulwark caps and around the transom. One client bought a portable welder with an hour meter on it ,before beginning his 36 origami boat. By the time he launched her, he had a total of 350 hours on the hour meter for the whole project. The tahiti ketch, or most non origami boats would have been many , many times that amount of fitting , cutting and welding.
Origami boats are far more forgiving that dinosaur methods when it comes to accuracy of cutting and fitting required.I usually let the owner do his first ever cutting on his own boat.It was never a problem.
Many of the labour seeking atitudes toward boatbuilding are a leftover from the puritan era, puritanism being defined as "The terrible, nagging fear that someone , somewhere, just might be having a good time."
Brent

Brent

Since this forum is home to many students and is relevant to the thread it's a good topic to pursue. I'd also welcome anybody else's input on this.


Frames don't limit dammage on small craft, they increase it.

That’s a very general and unsupported opinion. I will counter it by saying that when it comes to small boats( in most scenarios I can think of) frames can considerably limit the extent of collision damage, they are also very good at conducting operational stresses and stiffening the vessel globally . You can illustrate this clearly with a CAD model and an FEA package as you can model collision scenarios. We do this routinely for specific design.

Also consider that framing will often buckle before the plate actually ruptures which will further absorbing impact energy and limiting damage. This can be accomplished by the designer if designed for.

Anecdotal evidence is just that and it proves nothing, for example:


One of my 36 footers hit a sharp rock doing hull speed. It bounced off, undammaged . If it had frames the steel would have had something to stretch against and would have been holed at each frame.

When it comes to forward collisions lots of steel boats have hit rocks at hull speed with no damage, nothing to do with how it was framed, it’s more a factor of the collision contact angle at the point of impact. If the rock projected into the vessels path and the vessel was bluff bowed it’s going to significantly dent or hole it regardless.

Aluminium river boats avoid having transverse frames against the hull skin for this reason.

Again you extrapolate extremes , ships and light alloy craft are not even in the ballpark of the vessels we are discussing. They only work as compelling arguments to a neophyte.

Had the stringers been set on the frames in the BC ferry , instead of notched into them , the plating would have been creased the full length without holing.

This observation is just conjecture. One failure scenario I immediately envisage is that the panel buckles and the rock ‘catches’ then the tin opener effect so prevalent with ship plating would have happened anyway. How can you possibly know that this would not have happened instead ?

Without transverse frames it (the plating) simply bounces back. It is far easier to dent or hole hull plating if you hit it next to a frame, than it is hitting it where there are no frames.

Actually it takes far less energy to buckle a large panel ( buckling as in a permanent structural collapse ) than it does to stretch the material while it is restrained from buckling. Once the panel has started to collapsed it compromises all adjacent plating without frames.

This is a point you seem to misunderstand; in an extreme event the framing stops the panel buckling allowing it to yield instead . For plating to be sheared against a transverse is possible but historically its been shown to be a non event in smaller vessels. Sure you might hit the perfect condition for a straight shear but boy….. you’d have to be unlucky. Try using a guillotine (an optimized plate shearing device) with a gap equal to say 3 plate thicknesses.

When a sharp rock hits between frames, only hull plate thickness will prevent holing. Frames only help if you are so naive as to assume sharp rocks will only hit directly on a frame. When they hit right next to one , the likelihood of a hole being punched in goes up drastically.

Aren’t you over pushing this aspect (see my comment above). Smaller welded steel craft under say 35 tonnes have been common for around 60 years now in many guises; commercial military and leisure craft . They have shown that they have a remarkable resistance to being holed in underwater collisions. Sometimes I have seen fishing boats with wasted plating holed this way but often enough they remained intact and watertight .

To get some perspective in this is important, it is usual for steel boats after pounding on a rocky shore to survive dented but intact.

Even you are trading on the well established durability of metal boats which has been established by traditional construction techniques.

Ships are a different story. What was the plating thickness and the displacement of the ferry you are quoting I have no idea but lets say around 10mm (very generous )and 500 tons ?
In comparison look at a 6 tonne steel vessel plated with 5mm lower plate. Looking at a single framing adjacent shear and simply sitting the vessel on a rock; the ferry plating has to cope with stresses that are not 10 times but 40 to 50 times greater. I could go on about energy of the collision since this is a dynamic event. Lets just say it is very very unlikely to happen on the smaller steel vessel even beam on, and head on its almost impossible if the stem and keel LE angles are half reasonable.


The framing I used on my first steel boat served absolutely no useful function, just made the project far more labour intensive, and heavier. Thus they were a total waste of time, time which could have better been spent using the boat for what a cruising boat is for, cruising.


But then don’t extrapolate this to all framed vessels for the sake of trying to market your designs. It is just not applicable in modern optimized framing based designs. You seem stuck in the past with that an over-framed Tahiti. We have actually moved on from there you know.


If you invent many ways to make a boatbuilding project far more time consuming and labour intensive, and these self made hinderances don't change the way a boat looks or sails , does that automatically mean they are useful? Only if the enjoyment of building the boat is the the only reason for it's existence, or maximising the number of man hours you can justify charging a client. Perhaps this is a major source of objection to my efforts to bring ownership of good steel boats within the reach of the not so rich. I'm sure livery stable owners once had similar objections to those new fangled horseless carriages. I have pulled together 36 foot hulls in three days or less, something you are extremely unlikely to accomplish in a backyard built framed boat.


What are we talking about here How do 10 bar frames and some associated stringers escalate the cost significantly ? And then you might get a hullform you really wanted rather than on that is dictated by a construction method .

To compare recent figures for a 37 foot chined hull. At launch the hull steel including welding consumables had cost around 8% of the total expenditure and closer to 5% of the boats re-sale value. You can quickly see that both the saved cost (and time) rapidly diminish when you consider the finished vessel.

Attaching plate and stringers to frames before welding is a major source of distortion, which is non existent in frameless hulls, and common on framed ones.

Not quite sure what you mean here but pro built boats show no distortion while over-welded amateur built boats can be an eyesore. I suggest people take a local welding course and learn about weld shrinkage and how to compensate for it or hire a pro to assist and the problem disappears. You assist your clients as part of the package?

The less you do to a piece of plate , the fairer it will remain. Thus simplifying the building proccess is a good way to increase the odds of a hull remaining fair.Weld shrinkage only improves the shape and fairness of origami hulls.

There are some beautifully fair stress free round hulls rolled heat formed and welded in relatively small sections from masters of the art. They do a huge amount to the plating and the frames pull the last of it into line.

On weld distortion ditto my prior comment.

But what about repairs? Weld distortion is something that framing actually counters very well. We even add framing specifically for this when repairing.

As for Dutch technology, I've sent quite a few books and sets of plans to Holland, thus introducing advanced Canadian technology to them.

I think you’ll find that they precede you by many decades. Many barges were built on a flat floor, plating first and then framing and they pulled the plates together to form the hull prior to framing . Many of their smaller sailing boats so built were essentially frameless with a bulkhead integral tanks and deck beam brackets the only side stiffening, one such boat (with 10mm bottom plate) circumnavigated in the 50’s. Are you really unaware of this? The style and limitations of these sorts of hulls did not suit the market and they did not become commonplace again in Holland until VandeStaadt re-adopted some of the methods for smaller lightweight sailboats.


This is your reply to the comment that it would have been quicker to plate an existing frame

The only welds on a 36 ft origami hull are the centrline, two 14 ft chines amidships, four 6 ft seams on the bottom, two 5 ft seams on the bottom, bulwark caps and around the transom. One client bought a portable welder with an hour meter on it ,before beginning his 36 origami boat. By the time he launched her, he had a total of 350 hours on the hour meter for the whole project. The tahiti ketch, or most non origami boats would have been many , many times that amount of fitting , cutting and welding.
Origami boats are far more forgiving that dinosaur methods when it comes to accuracy of cutting and fitting required.I usually let the owner do his first ever cutting on his own boat.It was never a problem.

The point was that you have to loft the entire side then cut it so that you can pull a seam together and get a uniform gap before it’s stitched up so precision is very important and it will take longer and be harder to achieve than plating an existing and complete chined frame that can be done in what 8 plates total ?


Many of the labour seeking atitudes toward boatbuilding are a leftover from the puritan era, puritanism being defined as "The terrible, nagging fear that someone , somewhere, just might be having a good time."Brent

What percentage of the time of the construction of the whole vessel are we actually addressing? I would suggest 1% or less. Is that really significant? People can actually really enjoy the framing stage and hone their welding skills prior to tackling the plating.

People who want tobuild their boats, usually have a very definite idea of what they want and framing is a strong durable sensible and very well proven construction method no matter what you say.

Origami boat building appears to be a fast way of producing a hull consisting of bottom and side plating but sans deck. Presumably you then have to fabricate and add deck beams before plating the deck?
Ring frame methods lend themselves to quite rapid deck building while I can see that this is the point that the frameles origami style will suddenly bog down to conventional speed (or even possibly slower)……….is this correct?

Also the significant flaw is that this method you push is severely limited to certain hull-forms in it’s suitability. Many people want something different and they will need to use conventional/modern framing techniques since there is no sensible alternative. There is absolutely no benefit to you to continually claim otherwise (that I can see) .

When I get time I’ll post some computer simulations of modes of failure which should be illuminating. To be meaningful I need to know your designs maximum unsupported panel width length and thickness.

Here's an example of the type of study we can do. As a predictive tool it's very close and it saves all that destructive testing we used to do :)

Yes, I'm sure it's a lot of fun doing things the hard way when someone else is paying you by the hour to do it. More time= more pay , at someone elses expense.
The implication that all cruisers can afford to hire a so called professional to take a long tedious outdated method to build you what he decides you need, is elitist, and an insult to low income people who want to get off the treadmill.
Take a sledge hamer and hit a framed boat next to a frame . It will dent easliy Take a pickaxe and you will punch a hole it, it. Hit it away from frames and it will dent far less and probably not be holed.
Welding plate to frames , then doing the longitudinal welds will cause distortion between them.
Not every cruiser can afford to hire you to take your time , paid by the hour to get her perfect. With origami building techniques, shrinkage of longitudinal welds simply forces more compound curve in the topsides, reducing distortion.
Take a sledgehamer and pound next to a frame on a lightly plated framed hull . It will dent easily. Hamer betwen frames and it will be much harder to make the same dent.
All my decks are done origami style , which lets me fabricate and install allthe decks on a 36 footer in 8 hours. It lets me weld all the beams and stringers on a workbench before installing them ,eliminating a lot of overhead welding. Try it.
Most of the framing distortion in amateur built boats is from welding the hull to frames, then doing the longitudinals.With origami building, welding shrinkage simply forces more compound curve into the topsides plate making the hull even fairer.
Origami boatbuilding is a lot more forgiving in terms of the accuracy required than framed construction. Give or take an inch doesn't make much difference in the finished boat.
I think you should read my book so you will have a better understanding of the matter.
My current boat cost me $4,000 to get launched. To get her sailing , and liveable took another $2,000. $4,000 is definitely not 5% of $6,000 unless we use your mathematical skills.

When I try to post on this site , I keep getting logged out every a couple of minutes. Sorta kills ones enthusiasm for continueing on this site. Does this mean that when you say anything that someone doesn't agree with it gets erased?

Brent Swain

When your computer models tell you one thing and a boat pounding in 8 ft surf for 16 days tells you another. I'll take the pounding test over your computer numbers.

Length of the panel in a hard chine boat is the distance between chines or chine and deck or chine and centreline, a distance that is supported by longitudinals , which being portions of arcs , have to be compressed longitudinaly rather than simply bent ,as is the case with straight transverse frames..Got cut off again. Someone is obviously trying to silence me on this subject.
It is obviously far easier to bend a relatively straight frame than it is to compress a longitudinal on end , especialy when it is welded along a curve.
I'm of to another site.See ya when I see ya.
Brent Swain

With a steel boat many of the details are simply fabricated out of hull scraps and scrap stainless which are welded down ,eliminating a huge expense that fibreglas boats experience. Thus the finished steel work on a metal boat is a lot more than a shell of a fibreglass boat .Anchors that cost the fibreglas boat builder hundreds of dollars are simply welded out of left over hull scraps.

Yes, I'm sure it's a lot of fun doing things the hard way when someone else is paying you by the hour to do it. More time= more pay , at someone elses expense.
The implication that all cruisers can afford to hire a so called professional to take a long tedious outdated method to build you what he decides you need, is elitist, and an insult to low income people who want to get off the treadmill.

I thought this was principally about owner builders, that’s what I’ve been talking about anyway.
Hiring an experienced welder for 2 days and budgeting that into the cost and it may be worth working 5 days on the treadmill to pay someone like Murielle to come and do it.

Take a sledge hamer and hit a framed boat next to a frame . It will dent easliy Take a pickaxe and you will punch a hole it, it. Hit it away from frames and it will dent far less and probably not be holed.

This goes for any stiffener, longitudinal frame, transverse frame, floor, bracket etc in contact with the hull plate, but you are not going to do this unless using plating that is woefully lightweight.

Any realistic scantling that I would recommend and you would hardly mark the paint with either a sledge or a pick. Go into your garden and put a pick axe through 5mm plate sitting on the ground and post the photo. You’ll need some special powers and a matching cape.

Now take a wrecking ball equal to the mass of the hull , restrain the hull and swing it. Then assess the result and you will understand controlled and uncontrolled collapse and just what framing can do. You saw the photo of the steel yacht hit by the freighter in the Canary Islands.

Some boats are specifically designed for collisions , it should come as no surprise that they have plating supported by significant and closely spaced framing.

Welding plate to frames , then doing the longitudinal welds will cause distortion between them.

Which is why it’s recommended to weld the longs first and them the transverses.

Not every cruiser can afford to hire you to take your time , paid by the hour to get her perfect. With origami building techniques, shrinkage of longitudinal welds simply forces more compound curve in the topsides, reducing distortion.

Ditto above

All my decks are done origami style , which lets me fabricate and install all the decks on a 36 footer in 8 hours. It lets me weld all the beams and stringers on a workbench before installing them ,eliminating a lot of overhead welding. Try it.

But with flat bar chine ring frames they can all be welded before hand, including the deck beams. Plating is then a very simple affair. No where near as hard as you are trying to paint it. For you to make fair comparisons compare your method to a modern VandeStaadt (they produce very quick easy built hull designs) rather than one particular design of old.

Origami boatbuilding is a lot more forgiving in terms of the accuracy required than framed construction. Give or take an inch doesn't make much difference in the finished boat.

This is ok if the error is faired gently into the curve, but you cannot have this sort of error as deviation from any pair of lines to be joined without some very poor consequences. This means the lofting will need to be accurate (to define a welding gap) in this regard and it will always be quicker to plate the existing chined frame that you were talking about.

I think you should read my book so you will have a better understanding of the matter.

I have not been questioning your method or your designs , I am questioning your vocal opinions and comments attacking methods which don’t suit your marketing paradigm. The whole ‘framing is obsolete I have the answer’ argument.
People come to the forum to discuss ideas. This is what we are doing.

You are here, you wrote your book, this is a forum, I’m questioning your wisdom and you are free to explain your reasoning.

My current boat cost me $4,000 to get launched. To get her sailing , and liveable took another $2,000. $4,000 is definitely not 5% of $6,000 unless we use your mathematical skills.

So many self built steel hulls sit in the garden because the fun bit (the building cutting welding) is over then they find the engine,prop and shafting is going to costs more than the hull cost them to get to that stage.


When I try to post on this site , I keep getting logged out every a couple of minutes. Sorta kills ones enthusiasm for continueing on this site. Does this mean that when you say anything that someone doesn't agree with it gets erased?

No there’s no conspiracy, have you tried contacting the moderator? If this happens it is not due to any moderation .

When your computer models tell you one thing and a boat pounding in 8 ft surf for 16 days tells you another. I'll take the pounding test over your computer numbers.

I’ll take the computer simulation when it comes to failure modes and just how the plate will distort against anecdotal tales any-day. Anecdotes have a tendency to be misleading and are often misrepresented particularly when used for marketing.

If you look around you’ll find numerous vessels have survived this sort of calamity even some smaller lightly built foam-grp vessels . The key to the level of damage is how the vessel is oriented to the incoming waves. Most hulls will cope with the pressure head and slamming load . I have seen a solid GRP vessel on rocks hit by waves every high tide stay intact until removed months later, and come to think of it even a ferro hull the same, by the same token I’ve seen holes punched in ferro boats holed after grounding just from the bump from the wash from a passing trawler . All useless anecdotes really.

Length of the panel in a hard chine boat is the distance between chines or chine and deck or chine and centreline,

That would be the width if there are no transverses (the shortest dimension) the panel length if there is no transverse support will be equal to the whole chine.

Got cut off again. Someone is obviously trying to silence me on this subject.

No …..contact Jeff if this happens it’s the computers not the people and should be easily sorted. Composing your reply offline and posting it after logging on should work fine in the meantime.

It is obviously far easier to bend a relatively straight frame than it is to compress a longitudinal on end , especialy when it is welded along a curve.

Curvature on this scale adds very little the strength, the radius of curvature is fairly small for a longitudinal.

that is supported by longitudinals , which being portions of arcs , have to be compressed longitudinaly rather than simply bent ,as is the case with straight transverse frames..

But you are rather confused here:

An inner longitudinal welded to the plating becomes a T section. If you load the plate (the longitudinal becomes the web of the T), you are not compressing it , in fact the plating shifts the neutral axis of the T closer to the outer edge of the longitudinal (even completely off it if you consider the full plating) making it predominantly a tension member, the plate is the compression member.

For the longititudinal to be in compression it would need to be on the outside.

Furthermore structures like this fail in buckling and the difference between the (slightly) curved and straight stiffener will be zilch to a significant impact.

With a steel boat many of the details are simply fabricated out of hull scraps and scrap stainless which are welded down ,eliminating a huge expense that fibreglas boats experience. Thus the finished steel work on a metal boat is a lot more than a shell of a fibreglass boat .Anchors that cost the fibreglas boat builder hundreds of dollars are simply welded out of left over hull scraps.

There’s a break even point where it’s worth working and buying fittings rather than fabricating them, but yes for the budget conscious builder with time on their hands (or just the desire to do it yourself) it is worthwhile.
This is the owner builder scenario with time but limited budget that we were talking of about the hull. The other scenario is pro built which we were not talking about but that you used in the first comment.


I'm of to another site. See ya when I see ya.

Brent in your favor; you are an experienced sailor and boat-builder your designs are original, you have my admiration for that.

However if you post what appears to be misinformation expect to be questioned and be prepared to give reasonable replies. There’s no conspiracy here to silence you or make a fool of you. I have said I’m not picking on your design but I am rather being forced to defend framed designs because of your comments. You appear to have a few biased misconceptions about just how structures work. You also appear to hinge much of your argument on some fairly minor detail. That should not concern overly except to get you to stop the in the face marketing comments that another poster had already suggested that you to stop.

Keep promoting metal boats but please get your arguments in line. There are reasoned errors and beliefs, the latter has no place in marine engineering. If views are actually based on reason then they can change eh!.

Mike,

Well arguemented, and engineering wise, correct.

We have all seen "frameless" boats being built for decades now, Brent is certainly not the only one to be doing so, but he does push his barrow rather hard.

Thank you for so politely applying another persons opinions. I would like to say facts, but it seems that we are in an ever changing world today, and maybe facts as we knew them will be modified to a new science as we speak. Have you all been following the HHO gas thread. I just love changes for the better, and we are all learning new things every day if we wish to open our eyes, but don't shut the mind.

Landlubber

The basics of mechanics of solids have changed little over the last 100 yrs, only a better understanding of failure modes . The real advances are in materials and now recently, our ability to analyse them. With isotropic materials (metals) the FEA package has been a very useful design tool and is the greatest advance so far.

Frameless boats are a misnomer, plate has to be stiffened one way or another otherwise it will flex excessively or even collapse under load. I see that Brent actually uses longitudinal frames after pulling the hull together with this I think they have no choice since the hull is allowed to take whatever form it relaxes into after welding which will not be entirely symmetrical so any bulkhead or transverse will be highly problematic.

You can get away with a few basic design errors in 31 and 35 foot steel boats, but if you are talking as Brent mentioned up to 50 feet I am very skeptical that this can be done without some transverse stiffeners to carry the longitudinals without the latter becoming overly large. Structural design is no place for mis-information and unchangeable opinions ...it's just materials loads and stresses, and calculations that can be checked by others.

cheers

I switched to angles for longitudinals long ago to prevent them from falling over, or buckling. Until they do , the longitudinals, being inside the hull are under compression, and don't compare in any way, structurally ,with a flatbar longitudinal on a flat surface. Only when the surface becomes flat are they under tension rather than compresion. While curved, they are no more under tension that the stones in the bottom of a Roman arch.They are far stronger than a flat bar on a flat surface. The topsides , being sections of cones , are far stronger structurally than a flat surface and thus the only unsupported panel is the distance between the decks and longitudinals, or chines.
The 1/8th inch plate commonly used for 30 footers is easliy dented, especialy next to a hard point, like a frame.
I suggest any one who doesn't quite comprehend the structural stiffness given to a hull by shape , tack together a model frameless hull from sheet metal , and try to deform it. Without the decks on, it can be twisted easily. Once the decks are on it is very difficult to change the shape in any way.
The huge structural strength of fully welded bukheads, that decks and chines, and the longitudinal curves represent are as strong structurally as anything you will find on a boat. They make transverse frames as redundant as reinforcing a steel hull with paper mache.
I once tried to force the conic curve out of the end of a 36 footer. I cranked a 12 ton hydraulic jack rock hard without moving it in any way.
Like a shoebox, with the lid off, it is easy to change the shape. Put the lid on and it becomes much stiffer. With a full sized hull and deck you can put your most powerfull hydralic jack on the end of a post on one chine and against the hull deck joint on the opposite side and crank it rock hard without changing the overall shape in any way. You'll only bulge the plate out locally where the jack hits it. To change the shape you would have to stretch the deck and hull plated diagonally.
Much of ther distrust of origami boats comes from a failure to understand the geometric proinciples involved. Much of the unjustified faith in transverse framing comes from a failure to understand the geometric principles involved, and from looking at a single cross section of a boat in isolation, without considering the overall shape . The contribution of shape to the overall structural strength of an origami shell becomes very self evident as construction proceeds.
My boats have survived so many serous poundings on lee shores , coral , rocks, collisions with freighters, barges, icebergs, etc , that you are unlikely to find one that they haven't survived. Their structural intregrity has been proven time and time again beyond any reasonable doubt. Thus doubts are clearly an indication of a lack of understanding of the principles involved.
A friend started building a Van de Stadt 34 at the same time as I started a 36. I had the hull and decks together by the time he had the frames built. I had the entire shell built and fully detailed by the time he had the bare hull plated.
There is no way you can do the huge amount of cutting , fitting and welding of a multi chine hull with many full length chines in the time it takes to do an origami boat.
I do admire Van De Stadt for being one designer who took advantage of the properties of steel without being hide bound to copying wooden boat building, and thus not holding back advancement in steel boatbuilding thinking..
Of course building any boat , origami or otherwise, you use a batten to make the lines fair. In origami all it has to be is fair, regardless of accuracy , to get a fair hull . In traditional imitation wooden boatbuilding far more accuracy is required.
I use origami methods for hull, decks, cabins, cockpit, keels, skegs and rudders, not just the hull. They have been standard sheet metal practise since the ancient Egyptians , in fact ,for as long as sheet metal has been around.
I have taken measurements from the chine to the hull deck joint on several of my hulls , They were symetrical to within 1/16th of an inch.
If you take 6 square plates and join them corner to corner, then the end result cannot be anything but square. It is geometricaly impossible for them to be anything but square , as long as the original plates were square. The same principle applies to more complex shapes like hulls and decks. As long as the hull plates for one side are copies of those for the other side and the decks for one side are copies of those on the other side, and they all join up at the same relative points, it is geometricaly impossible for the resulting shape to be anything but symetrical.
The huge expense in imitation wooden types of steel boatbuilding explains why there are so few around. They are rarely built.
Like the livery stable owner, it is understandable that someone who has spent decades aquiring a huge amount of knowledge would not aggree with any new technology that threatens to make his vast acumulation of knowledge outdated and redundant. Those who cling tenaciously to outdate methods of a steel boat building are modern day boatbuilding equivalents of livery stable owners.
As Ongola said " When a new idea comes along , it goes thru three stages. First , it is ridiculed. Then it is violently opposed, Finally it is generally accepted." Origami boatbuilding has reached the generally accepted stage , here on the BC coast, after having gone thru the first two stages decades ago. There are bound to be a few backward holdouts elsewhere in the world , where they are still at stage one or two.
They remind me of the guy I met in Victoria who was in the government maping business. He was complaining about a guy with a computer who was scooping up all the work and putting him out of work. The solution was simple . Get a computer and learn his methods.
Ditto modern boat building methods. Learn more modern methods, when what you have learned threatens to become redundant. It's not that difficult ,and streamiling the building procces brings the cost of building down to where you will have a much larger number of potential clients to build for. Give up the livery stable business , and learn about horseless carriages. This is the 21st century , after all!
Brent

You do keep repeating the entire mantra, much of which we have already discussed. But lets look at the more serious misunderstanding.

…………….. , the longitudinals, being inside the hull are under compression, and don't compare in any way, structurally ,with a flatbar longitudinal on a flat surface.
Only when the surface becomes flat are they under tension rather than compresion.
While curved, they are no more under tension that the stones in the bottom of a Roman arch.
They are far stronger than a flat bar on a flat surface.
The topsides , being sections of cones , are far stronger structurally than a flat surface and thus the only unsupported panel is the distance between the decks and longitudinals, or chines..........

Understand the difference between an arch and a curved beam:
(Apart from also apparently misunderstanding collapse under compression and just how structures achieve their strength )

For a structure to be considered an arch you must increase the curvature to the point where the axial forces become significant. An arch has to have a very small radius in comparison with the element thickness. For the longitudinal curve of a boats hull the radius of curvature is variable, on a 36 footer it will vary along the length ballpark within what 20 to 50 feet? What are your element thicknesses, 3/16” ?
This is just too shallow a curve by a massive factor anywhere on the hull for the thickness of the material for it to be considered anything other than a flat beam for the purposes of structural support.

Even frames and plating on a tightly curved developed bilge are only a little better since the element thickness is so thin in comparison to the radius of curvature.

As curvature increases you can count on going down to around 20% less material with a tight curve in plating and framing and this is counted in the Curvature coefficient applied to curved members and plating. In your case this would not even be applicable to the hull longitudinal. Also be aware that unsupported curved surfaces can Pop-through into an inverted state with little energy absorbing and no stretching from a significant collision.

As for tension and compression you consequently misunderstand this. It would pay for you to try and grasp correctly some basic theoretical structural engineering concepts. There are also some good engineering forums where you could engage in educational discourse and try out your ideas incognito.

I am concerned that you are looking at local impact strength but losing sight of the requirement to design the whole for a pressure head. A mid-30 foot boat is going to be forgiving with respect to these sorts of misunderstandings. A larger vessel could be problematic with your current level of understanding applied.

Also get it into your head that modern scantlings are not hangovers from wooden boats we have moved on. Even the Van de Staadts you admire comply with class society rules.

Do you accept the curvature information or would you like more on this?

As for origami accuracy… yes if you loft it accurately and weld with care but then that differs with your earlier statement about lofting accuracy not being critical ; since it is your analogy try joining your 6 square faces with half an inch error in the edges and an error in the first weld angle. :)

Brent, you still don't seam to get that most people don't have anything against the origami building method. Most people will recognize it is an interesting method among others. As you stated (quite enough) it may have its advantages. You should also recognize that it has limitations which don't suit some peoples needs. It would be wise for your reputation to stop insulting the rest of the boat building community with your little snags about dinosaurs and horse carriages. If you opened your mind a little bit you would find out that there are good reasons why different designers and builders pick different methods and that many of those who design and build framed metal boats these days do so with some very modern technology. You seem to pick your comparisons with a fairly narrow mind. We are not all out there cutting frames with a hack saw and welding with our grandpa's sticks.
Most of your reasons to praise origami boats are not wrong, most of some other peoples reasons to not want an origami boat are also not wrong. Can you accept that? You would do a much better job advertising your views if you did so with respect.

On the structural argumentation, I have been tempted to jump but in but Mike has been doing a way better job than I could with a nicely structured argumentation. I have enjoyed the read. By the way, thanks Mike for offering my welding services to Brent. I'm honored you picked me, but unfortunately, we are located at opposite ends of Canada and I am fairly busy.

Cheers
Murielle

M&M Ovenden, MikeJohns, Brent

I've had discussions with our esteemed "virtual colleague" in other venues and do admit the Brent can be a bit less than willing to agree to any other point of view- separate from his own.

However, I noticed a few items that may be unimportant but wanted to remark to Mike about them so that these points are addressed in his great "theory of metal structures for the non-engineer" post.

One item Brent keeps mentioning is how the longitudinals inside the hull are in compression which he alleges is a very significant factor in the stiffness of these hulls- and that results from how the longs are installed.

Before the flat half hull shape is pulled up and even before the 'dart' amidships is drawn in, Brent welds the longs to the hull plate- flat. This is a bit different than adding them after by plating over them since they're welded flat to a flat sheet.

So when these longs are welded to the hull first, then the hull half is drawn in at the midships 'dart' and finally pulled to the centerline to meet the other half- well that does seem to compress the longs in a way that is unique to this method.

Sprung around ring frames they're in tension and that may relieve when welded to the hull. If they were added to a hull after the hull were tacked up, they'd still seem to be in tension along the outer edge anyway - but here they seem to be compressed by the curve of the plate after they're welded to that plate- while flat.

I'm not defending Brent's poor manners, they're posted for all to see, and I've mentioned to him in the past that his anecdotal accounts are meaningful only if someone is the exact circumstance- but I did want to say that his idea of compressing the longs probably comes from the sequence in which they are added in this method of construction.

Now, are they 'magical-longitudinals' as a result? No, I'm not saying they are but I wanted to note this in case Mike is willing to reflect on the effect of this sequence of assembly; good, bad, or no effect from deforming the hull with the longs already on the panels when you pull them into their half hull shape?

Mike, if you have time, I'd surely appreciate any continuation of your remarks which have been very informative and I've enjoyed greatly.

Thanks for the explanations you've provided.

Cheers,
kmorin

KMorin

Thanks for explaining that, initially the inner will be under some compression and at least something is clear,I can see some of Brent's reasoning now. :)

However this pre compression is only induced within the member itself from internal stresses and it does not increase with external load as in an arch but shifts quickly into tension (and of course in makes no difference to shear ). The pre-stress will add local stiffness, but very little in the way of global strength when you consider once again both the element thicknesses and the relative radius of curvature.

By way of basic illustration:
If you made a beam on the flat with the longitudinal stiffener and add the plating with width of 15 times its thickness as a flange over the length of the beam (vessel length ?) and then draped it over a formwork representing the vessels side. After affixing the stern end, I suspect a 5 year old could pull it into shape without too much effort . In reality this is the level of pre-tension added strength from the longitudinal that needs to be overcome before it acts as a normal beam................virtually zilch.

The longs are helping fair the plating curvature and acting as local stiffeners but they are not global strength members.

To be significant the longitudinals would need to be both large in section and without any transverses they would need to be very well supported (from tripping).

Structural collapse is a lot more complex than this and there are other factors at work which are more of a concern with a semi stiffened monocoque without any transverse support. Suffice it to say that I am very skeptical that larger vessels will have sufficient global hull strength built to this method. ( Brent was talking in another thread of up to 50 feet). I would stick to mid 30's with his designs.


Cheers

They only go from compression to tension when the arc disappears and the surface becomes flat.
50 ft origami boats have endured a lot of torture tests, with no structural problems whatever.
It is always amusing when someone states that something that has been working well for decades , and many torture tests " Won't Work".
Brent

Brent
The surfaces are fully restrained by adjacent elements. All that is required is for the locally applied force to be greater than the relatively low local pre-stress and then you are immediately back in conventional failure analysis.
Neither the curvature nor the level of pre-stress is enough to count as structurally significant relative to the types and magnitudes of applied loads and forces that we actually design to.

I would be very wary of a 50 foot hull If they really have been designed and built the same way. It is possible that their design strength will be well below accepted standards.

Anecdotal escapades are not a good basis for vindicating a design. If a designer wants to argue a different and specific construction method it is always up to the designer to prove the point with a proper analysis.

The idea of existing scantling rules is that they have been modified over time to take all this into account through both refinement of structural requirement and a detailed analysis of failures. If you vary from these methods you should have more than personal viewpoints to support your arguments, in other-words you should be able to show by detailed analysis that you have an argument worthy of consideration.

Tens of thousands of miles in some of the roughest waters on the planet is a very thorough analasis, far more thorough than mathematical theories. The sea has a way of finding the fatal laws in your theories ,quickly , and their naivete.
For safety I'll take the sea torture test over your mathematical theories any day.
Brent

The idea of existing scantling rules is that they have been modified over time to take all this into account through both refinement of structural requirement and a detailed analysis of failures.
If you vary from these methods you should have more than personal viewpoints to support your arguments, in other-words you should be able to show by detailed analysis that you have an argument worthy of consideration.

and why argue further :confused:

I have far more than personal viewpoints . I have over 200 boats built to my designs that have sailed all over the world , many times in extreme conditions and which have survived many torture tests that would have quickly and easily destroyed many boats that your numbers rate structuraly sound. Few , if any owners would want anything else. They rarely come up for sale.
If there is a weak point , hundreds of thousands of ocean miles will definitly find them , which is not neccesarily the case with your math.
Mathematicians have approved the space shuttle . How many of them have we lost ,percentage wise.
Your calculations say that most fibreglas boats are structurally sound and most approval agencies like Lloyds, ABS , etc aggree. So lets take a Lloyds or ABS approved fibreglass boat and have a demolition derby against one of my unapproved origami boats and see who wins.I wouldn't bet on the approved boat. So much for the credibility of their theories.
Brent

Brent,
I'm no naval architect, far from it, but this has become ridiculous - you even go as far as using something that looks very much like the McDonald's argument (an explanation will follow).

Tens of thousands of miles in some of the roughest waters on the planet is a very thorough analasis, far more thorough than mathematical theories.
Really? Yes, one might think that on the surface, but the reality is, that many boats and boat types have sailed 100s of thousands of miles, with nothing happening. Until disaster struck and the people injured, killed and lost. All because of a flawed design that eventually opened up for disaster.

The sea has a way of finding the fatal laws in your theories ,quickly , and their naivete.
Sorry, but with that argument, an open boat could be argued to be great for arctic sailing.


For safety I'll take the sea torture test over your mathematical theories any day.
Brent
Funny, I prefer both.
Think about this (as an example): You can sail quite a lot in a boat that is build out of plaster, has quite a lot of initital stability, yet when encountering a certain type of sea state and wind force, it will roll (degree of vanishing stability, I think it's called in english?). Now, to makes matters worse, there's a hell of big hatch, set to starboard, so when it heels 80 degrees to starboard, water will enter, making the turn around even faster.
Now, the "designer" used the same argumentation that you do: Namely, that maths sucks, and science is no better than pocket theories, and so he didn't calculate how that extra weight would influence the stability, nor when the boat would roll, nor did he take into account that he would need to make a means to get out of the boat.

Now, such boats exists, and what you're doing, by way of "argumentation", is saying that we don't need anyone to calculate these matters. Because, as you imply, science and calculations can be wrong, thus everything calculated is useless.

I have far more than personal viewpoints . I have over 200 boats built to my designs that have sailed all over the world , many times in extreme conditions and which have survived many torture tests that would have quickly and easily destroyed many boats that your numbers rate structuraly sound. Few , if any owners would want anything else. They rarely come up for sale.

First of all, hundreds of thousands of miles have been sailed in less than ideal boats. You're simply spewing anecdotal "evidence".
Hell, Joshua Slocums spray was anything but a seaworthy vessel, but by your argumentation it must be a boat whose "qualities" is to be copied.

Secondly, your point about your designs rarely coming up for sale, and therefore they must be seaworthy, is using statistics as the devil reads the bible. There can be numerous reasons for why your boats rarely come up for sale (how do you even know, btw? Those boats can be sold without you knowing, and without being advertised, for all you know). One of the reasons might be that circumnavigator boats people build themselves rarely are sold off. Or that the boats themselves won't fetch a good enough price. Or numerous other reasons. Besides, them not being sold is just a claim on your part, evidently to support the notion (by you making a logical leap) that they thus must be seaworthy.

Third, the McDonald's argument: Many people eat at McDonald's so it must be healthy, wholesome food. Now, compare that to: "Many people have build my boats (200), thus it must be a seaworthy design". Now, go a take a look at a bayliner or a sea ray. They must be many times more seaworthy than your design, if we're to follow your argumentation.

If there is a weak point , hundreds of thousands of ocean miles will definitly find them , which is not neccesarily the case with your math.
Read my example above.

Mathematicians have approved the space shuttle . How many of them have we lost ,percentage wise.
Show me to a place that will state that it was because of poor math the shuttles were lost. Do that, and then you might have a far fetched point. However, even if you could (you can't), it wouldn't prove that math and scietific theories are flawed, even though you wish it so.

Your calculations say that most fibreglas boats are structurally sound and most approval agencies like Lloyds, ABS , etc aggree. So lets take a Lloyds or ABS approved fibreglass boat and have a demolition derby against one of my unapproved origami boats and see who wins.I wouldn't bet on the approved boat. So much for the credibility of their theories.
Brent

Ah, yes, because a demolition derby will certainly prove anything. Besides, it's a free suggestion, well known in the political world. The reason being that you know full well that a demolition derby will never happen, and so does the reader, and because of that, you somehow think you have "proved" your boats are perfectly seaworthy. "because otherwise, the opponent would have agreed to the derby". It's a logical fallacy, and even worse, it's intellectual dishonesty.

Now, you might conclude that I'm against not following "the rules" – that I'm against thinking out of the box. Well, I'm not. What I'm saying is that if one has to break proven rules and go against established facts, math and science, one better be able to argue one's case. If not, you're simply not trustworthy intellectually.

In fact, the argumentation reminds me of the creationists' ditto, who simply denies science is fact based, and if they can find one scientific fact that is later proved to be wrong, then all science must be wrong. And that, Brent, is simply honest ignorance (in the best sense of the word) or intellectual dishonesty.

Pick ax, sledge hammer, torture test, fiberglass boat....that triggered a little souvenir from last summer I thought of sharing. I'm not quite sure it fits on this thread so I posted it in materials. I wasn't really trying to make a point, just share an experience.
But if there was a point to be made it would be that a well built fiberglass boat could surprise the most hard core steel lovers, I was surprised myself by a not so well built composite hull.
Yes, Brent I realize that a sound steel boat can make a lot of damage to a fiberglass boat.

http://boatdesign.net/forums/showthread.php?p=203512#post203512

On an other note. Their seem to often be confusion on the reason being of construction rules, regulations as scantlings or approved welding rod, metal grades.... Those rules are not saying that nothing else will work, they're providing a solid base to guaranty quality. As previously mentioned those rules were established over time and based on experience ( not 200 boats.... just a few more over history). Numbers have come in play only recently. They have greatly improved our capability to translate experience from older technology to new ideas. Numbers are only a language used to clearly compare and describe physical properties. The numbers complement real life experimentation by greatly reducing the need for destructive test to find the material and structure limits. Real life situation still teaches a lot. When an accident happens, the situation gets analyzed and translated into numbers to improve regulations. The numbers don't stop evolution or new ideas. Number crunchers would become useless if there were no new ideas to crunch numbers on. Presented properly with a good argumentation a new idea can lead to a new standard.

Murielle

Yes, you start with mathematical calculations, then apply experience and logic , letting experience and logic overule when the two disaggree.
When math says a boat won't survive pounding across 300 feet of coral in a 12 foot swell or pounding 16 days in 8 ft surf on a west coast Baja beach or bashing thru the NW pasage in a single season, and survive hurrcane force winds in open ocean, yet boats repeatedly do with no damage, then your math is definitly wrong.

Had a a big response typed up and got cut of again. SOB.

A demolition derby will definitly prove which boat is the tougher one, beyond all reasonable doubt. Are you suggesting that in a demolition derby, that the boat which breaks up and leaves the other relatively undamaged is not neccessarily the weaker one , if your math decrees it to be so. That is self delusional. Of course such a demolition derby will never happen, because anyone with a fibreglass boat knows he won't stand a chance , thus conceding my arguement. All he has is theory, which he doesn't trust enough to put to a real test.
My boats that have sold , were all sold for far more than the owners had invested in them. Several 36 footers have sold for over $100,000 , and even roughly finished ones sell for around $65,000, still many times what their owners had in them. They all pass survey with flying colours , and several have been built under the watchful eye of well respected surveyors. The coast guard have admired and praised my boats, calling one the best built boat they had ever seen.
When people started building boats out of steel, all they had to go by were wooden boatbuilding traditions , which they became hidebound in, and have been ever since. Thus the formulas they came up with were arrived at on the assumption that the boat would be built using dinosaur wooden boatbuilding methods, methods that were developed for dealing with a material that only had real strength in one dirtecton ,and overal shape was less relevant than in a monocoque material. Thus they have held back steel boatbuilding, ignoring the many advantages steel construction has to offer. This is why one off steel boats are so expensive and time consuming and thus not more common.
I have hit origami hulls as hard as I could with the biggest sledge hammer I could find without dammaging anything. Been there, done that, many times.
Space shuttle ? Did they not use mathematical calculations to determine that the foam would never fall off the fuel tank and damage the shuttle? Did they never use math to determine that the O rings on the booster would never fail? If not, why not, given the huge amount of mathematical resources the space industy has ,and the predominant belief that math can determine every eventuality? Numbers must always withstand the test of logic, or become meaningless.
McDonalds? Go see the movie "Supersize Me". The proof is out here , like the poroof that origami boats are sound. Those who choose to ignore the evidence are suffering , just like those who ignore the well proven success of origami boatbuilding, and hire someone to waste their time and money on outdated building methods, and end up giving up years of cruising to pay for such wastefullness, or someone elses playtime.
My niece was learning to read . Her father was passing a McDonalds. She read the sign, turned to her father and asked "What does 10 billion survived mean?".
Brent

Yes, you start with mathematical calculations, then apply experience and logic , letting experience and logic overule when the two disaggree.

Funny, logic is deduction, and by definition applied math in the simplest of ways. All you do, is use some anecdote as "evidence" and then use conjecture to apply to all. As I have mentioned earlier, by your logic (as in deduction/reduction), any anecdote will do to prove things are perfectly safe.

When math says a boat won't survive pounding across 300 feet of coral in a 12 foot swell or pounding 16 days in 8 ft surf on a west coast Baja beach or bashing thru the NW pasage in a single season, and survive hurrcane force winds in open ocean, yet boats repeatedly do with no damage, then your math is definitly wrong.

See above: By your "logic", it's perfectly safe falling out a five floor apartment window, because the anecdotal evidence is there. Me, I think that's cutting it a bit too close.

Had a a big response typed up and got cut of again. SOB.
Did you contact Jeff about this issue? You really should. Otherwise, type it first in textedit (or notepad, depending on your platform), then copy/paste it here.

A demolition derby will definitly prove which boat is the tougher one, beyond all reasonable doubt.
Depends – are the boats rammed in the same position? Are some "overbuild"? Are some made especially for this demolition derby? Are some basically unmaneuvrable, and thus more susceptile to be rammed and on and on. There are many variables. Further, when we're talking about your designs, did you calculate the vanishing stability on them and is that available? How about flex? Did you calculate that? Too much flexing would mean it would be much weaker after a 100.000 miles, all things considering. You so want a demolition derby, even after I pointed out why that is nothing but rhetorics in order to convince the less than brilliant out there (yes, yes, it's a joke, alright – I'm not full of myself. It's just that when even I can see through empty claims, everyone ought to be able to).

Are you suggesting that in a demolition derby, that the boat which breaks up and leaves the other relatively undamaged is not neccessarily the weaker one , if your math decrees it to be so.
See above. Even now, you have made nothing but unfounded claims. Even the rhetorical demolition derby-winner is just conjecture. We haven't held one, but in your argumentation yours will come out the winner naturally.

That is self delusional.
See above. You know what is self delusional? It's self delusional claiming that some design and method you thought up is by definition better than "old school methods. Especially seen in the light that although you claim as much, you have provided no proof, no valid arguments, no nothing. Except, of course, your anecdotal evidence. Fifth floor drop-out, anyone?

Of course such a demolition derby will never happen, because anyone with a fibreglass boat knows he won't stand a chance , thus conceding my arguement.

Oh, haha, this is rich! That is the exact logical fallacy I warned about, how one would only put forth the demolition-suggestion, if used like this! Excellent! You just proved the point, that it's mere rhetoric, a logical fallacy, a strawman:


Ah, yes, because a demolition derby will certainly prove anything. Besides, it's a free suggestion, well known in the political world. The reason being that you know full well that a demolition derby will never happen, and so does the reader, and because of that, you somehow think you have "proved" your boats are perfectly seaworthy. "because otherwise, the opponent would have agreed to the derby". It's a logical fallacy, and even worse, it's intellectual dishonesty.

Now, okay, to follow your reasoning:
I have a very small strip plank open boat. It's five and half meter long, plus a two meter bow sprit. I will gladly put this to the test. Now, provide with your toughest build design, and we'll have a demolition derby on our own. What's that? You aren't willing to pay for the trip to Denmark, not to mention the transportation of the boat? Surely that means your boat is far inferior to mine … :rolleyes:


All he has is theory, which he doesn't trust enough to put to a real test.
Great to see you continue this Erasmus Montanus-route (Mother cannot fly, a rock cannot fly, ergo: mother is a rock).

My boats that have sold , were all sold for far more than the owners had invested in them. Several 36 footers have sold for over $100,000 , and even roughly finished ones sell for around $65,000, still many times what their owners had in them. They all pass survey with flying colours , and several have been built under the watchful eye of well respected surveyors. The coast guard have admired and praised my boats, calling one the best built boat they had ever seen.
Still naught by claims from your part. Claims you have yet to make into valid arguments.

When people started building boats out of steel, all they had to go by were wooden boatbuilding traditions , which they became hidebound in, and have been ever since. Thus the formulas they came up with were arrived at on the assumption that the boat would be built using dinosaur wooden boatbuilding methods, methods that were developed for dealing with a material that only had real strength in one dirtecton ,and overal shape was less relevant than in a monocoque material.


Oh, man, this really shows how ridiculous your argumentation is! You actually think you can argue that everything build today is built like that because engineers still think they're building in wood? And that, by extention, you're the great saviour, having come up with this "radical new method and thinking"? Come now, you cannot be that full of yourself, and at the same time be that ignorant.

Thus they have held back steel boatbuilding, ignoring the many advantages steel construction has to offer. This is why one off steel boats are so expensive and time consuming and thus not more common.
I have hit origami hulls as hard as I could with the biggest sledge hammer I could find without dammaging anything. Been there, done that, many times.
I have tried the same on a "fake" side of epoxy strip-plank (don't want to screw up the paint job) What's your point?

Space shuttle ? Did they not use mathematical calculations to determine that the foam would never fall off the fuel tank and damage the shuttle?
No. They used math, and then they tested the thing. But as you know, crap things happen when people butt in. In this instance, the surface was either not very well prepared, or they had a crap batch of glue. Just like each and every other of your anecdotal evidence, this doesn't prove that math can be disregarded in any way, form or fashion.

Did they never use math to determine that the O rings on the booster would never fail?
No, they certainly did not. Noone used math to prove that anything would never fail! What the hell are you trying to say with such a horrendously stupid strawman argument? Where do you get you information from? Do you know what "applied maths" are?
The O-ring failed, not because of poor math, but because no-one told anyone needing to know that the material used for the rings had been changed.

If not, why not, given the huge amount of mathematical resources the space industy has ,and the predominant belief that math can determine every eventuality? Numbers must always withstand the test of logic, or become meaningless.
Okay, first of all, you need to read up on the failures of the space shuttles. Secondly, you need to hone your skills when it comes to deduction, and make damn sure you're not using logical fallacies and therefore do all those leaps of logic you do constantly.
Thirdly,

McDonalds? Go see the movie "Supersize Me". The proof is out here , like the poroof that origami boats are sound.
You really don't get it, do you? I don't need to see that film in order to realise that McDonalds isn't a wholesome diet. That's my point exactly. The "McDonald's argument" is a way of showing people, why their logic is flawed, because everyone can relate to McD. It's a parallel for crying out loud. Just like my Sea Ray-example was a parallel. I could have said "You know what, there are sold more in walmart than any other chain, thus the best quality must come from there", or "Sea Ray and Bayliner sells the more boats than any custom builder, therefore they must be much better quality than any and every custom builder out there"<-- THAT, Brent, is "The McDonald's argument". It has naught, zero, zilch, to do with McDonald's.I'm amazed you didn't even get that.

Those who choose to ignore the evidence are suffering , just like those who ignore the well proven success of origami boatbuilding, and hire someone to waste their time and money on outdated building methods, and end up giving up years of cruising to pay for such wastefullness, or someone elses playtime.

Ah, yes, you're the saviour of the boat building industri …
Seriously, though, even though the term "anecdotal evidence" contains the word "evidence", it doesn't mean it's anything but "anecdotal", and anecdotal evidence really is just anecdotal.

I could build a bath tub with a lid and a stick and propably sell it too. That doesn't mean a well calculated hull, with proven scantlings and build methods is inferiour to my bath tub or in any way obsolete. It just proves that there are idjits out there willing to buy into anything, as long as someone is just making claims often enough: Hence christianity, judaism, islam, scientology, Jehovas Witnesses and any and every other sect out there. The number of people buying into unfounded claims doesn't mean the claims are suddenly founded.

My niece was learning to read . Her father was passing a McDonalds. She read the sign, turned to her father and asked "What does 10 billion survived mean?".
Brent
Yes, very apt when it comes to McD. You seem to forget, though, that I pointed out that _you_ used the McD-argument to prove _your_ boats were sound … In effect, you could then say that very thing about your boats :D

DanishBagger, MikeJohns, M&M Ovenden, Brent, all

I've given up some time past trying to hold the Brent to logic, as he's not so inclined. So I don't spend too much time over the noise but I do listen for any good information under the roar. Looking for nuggets among the less valuable rocks, so to speak.

The one aspect of origami that interests me is the shape issue compared to the other method of building.

As a function of the method of hull surface forming all the shapes ahead of the middle 1/4 of the hull and all the sections aft are more or less conic so the waterlines have to be much more straight than convex.

Given this severe (in my opinion) shape limitation, will there be a gain or loss to the same LOA/Displacement& B/L ratio hull's performance?

My sense is that the more fully convex curved shapes will have a dryer deck, perhaps not enough to notice? [As a non-sailing boater, I rejected the origami limits to power boat hulls although I use a vaguely similar method of construction.] I also sense that hulls with a more full waterline plan view curve will have a more rapid bow pitch in a swell, and that might be so slight a shape difference not to have any net effect?

Are there aspects of the method's legacy plate developments that are beneficial or detrimental to performance of a sailboat?

Cheers,

DanishBagger, MikeJohns, M&M Ovenden, Brent, all

I've given up some time past trying to hold the Brent to logic, as he's not so inclined. So I don't spend too much time over the noise but I do listen for any good information under the roar. Looking for nuggets among the less valuable rocks, so to speak.

The one aspect of origami that interests me is the shape issue compared to the other method of building.

As a function of the method of hull surface forming all the shapes ahead of the middle 1/4 of the hull and all the sections aft are more or less conic so the waterlines have to be much more straight than convex.

Given this severe (in my opinion) shape limitation, will there be a gain or loss to the same LOA/Displacement& B/L ratio hull's performance?

My sense is that the more fully convex curved shapes will have a dryer deck, perhaps not enough to notice? [As a non-sailing boater, I rejected the origami limits to power boat hulls although I use a vaguely similar method of construction.] I also sense that hulls with a more full waterline plan view curve will have a more rapid bow pitch in a swell, and that might be so slight a shape difference not to have any net effect?

Are there aspects of the method's legacy plate developments that are beneficial or detrimental to performance of a sailboat?

Cheers,

I feel somewhat obliged to reply, since you mentioned my name. First, no less, ha ha.
The thing is, I'm not a naval architect, nor a "seasoned" boat builder by any stretc of the imagination, but the way I see it, is that the way Brent is building (disregarding the utter lack of analysis and calculation) is that when build like that, the boat is gaining strength only from the form, meaning a hull too long, thus making the hull sides flattish will make his "design" loose a lot of rigidity and gain a lot a flex (which you don't want, of course). Further, the problem with the methods Brent's using, there's a somewhat set limit to how the hull can look, since it relies on hull-form almost exclusively (anyone who actually knows about this stuff, please reply and correct).

Speaking of hull-form: all things equal, a smaller hull will inherently be stronger than a bigger one (less flex because of less surface etc).
I think it was Murielle, who argued that a boat of 50 foot, built with Brent's methods wouldn't have the structural rigidity as the smaller design, and for all I can see, it seems about right, because at those lengths the plates are more or less flat, leading to flex, leading to fatigue. Well, that's how I read it, anyways, and if I misunderstood it, it's still pure logic. The convex shape is what makes an egg strong, after all.

Now, trying to answer your question about a dry ride the best I can as a pure amateur: I don't think one can say that a certain building method will give a dryer ride than some other method. It has to depend on design and basic hull-form, freeboard, speed, flare, flam, whether the boat is prone to hobby-horsing, have a slender stem and so on.

Now, would I go as far as far as warn against Brent's designs? Yes, I actually would. Not the building methods as such, but the very designs. The reason being, that if you go by something from him, he's indirectly admitted to having his customers check to see if his boats are seaworthy, and he has not calculated how well they do if knocked down. Those things has to matter if you're going to encounter harsh weather.

Please take the above with a grain of salt :)

I said it before and will say it again....

Firstly, if the numbers of boat plans Brent mentioned have indeed being sold / built, one must ask why?
And herein, according to my humble logic, lies the fact at whom it is aimed in the first place; people who want a build a boat, have limited or no steel working skills at all, knows nothing about hull lines as such and wants it pronto pronto. People prepared to pull a hull together with sledge hammers, chainblocks and what else that comes to mind.

Should you present to this "group" of people a set of chines/multi chine, or radius chine, round bilge or origami plans, what would they pick? Even more so if they can be convinced by some questionable facts and figures by someone.
I had seen photos of origami boat being "assembled" and the whole exercise reminded me of hillbillies at work ;) - no offense meant to anyone.

But back to the spirit of this topic - realistic scantlings; when I do a design, I supply my client with proper scantlings and as is the case with the 43ft gaff schooner on my drawing board currently, I showed my client my calculations and explained it to him in person how it was derived at and the dynamics involved. These calcs are based on scantling rules and recommendations that are proven and adapted over times. This gave my client (and myself) a sense of security to know the numbers and specs were not thumb sucked. With that goes proper stability calcs and graphs to name but a few.

Question, as seen with the arguments and logic from Brent, does he supply the same to his client, and if so, how did he derive at the numbers:?:

DanishBagger,
It's an odd day when I find myself taking a stance more in support of the Brent than against! But I need to remark about the Origami method and boats at least in passing. My remarks are more about the idea of origami than it's practice by the Brent.

First, these boats are strong and not flexible or flimsy and next their hulls do go together quickly almost regardless of your metal working skills. Not that makes much difference in the time to build a finished yacht.

So: is that the way Brent is building (disregarding the utter lack of analysis and calculation) is that when build like that, the boat is gaining strength only from the form, meaning a hull too long, thus making the hull sides flattish will make his "design" loose a lot of rigidity and gain a lot a flex (which you don't want, of course).

This idea is not fully founded, its not wrong to be cautious and the Brent isn't very articulate in regards logical discourse so you'd be hard pressed to find out why that statement isn't as accurate as possible.

These boats have an "analyisis and calculation" more in the traditional [wooden] tradesman's/boatbuilder's sense than on paper. The tradesman of old had Rules of Thumb and without bothering to submit them to an engineering examination the Brent has developed his own set of RoT; but only refers to them in obtusely stated arguments which I think cover the value of these lessons learned.

In other words, having studied the Origami method and specfically the Brent's scantlings individually; I find there are good design and structural features that may be covered from other's view and honest examination by the Brent's poorly worded rants about his "metalmessiahship".

The hulls are 3/16" or heavier (as far as I know) and that, for a <40' boat begins to approach the StrongAll method wherein the interior structure is reduced in favor of heavier hull materials. What has not happened (by the Brent as far as he has published) is a formal structural analysis of the boats; BUTTTTTTT!!!

With all that said, there are no instances of hull failure or even fatigue to call to question the method or the particular scantlings - design of framing of the existing hulls. It is embarrassing that the Brent refuses to find a more graceful means of making such a simple point- but there is the full history (perhaps archaic history of marine design) of boatbuilding to support concept that "tried and true" is valuable information.

I am not saying, as does the Brent in any venue he seems to attend, there is no room for improvement, no reason not to analyze or that these designs are the final word in metal marine forms. All I want to point out is that we need to look closely at what is really being built - and not be distracted because one of the builders of this method is rude to a fault.

So, while I can't agree with the bombast and noise that passes for discussion with the Brent, there is validity to building boats that are guided by rules of thumb- especially if you're building the same one over and over.

Am I discounting what MikeJohns has said? Not in the least, in fact I read those posts daily for a week being more informed each time I read. [I'd put MikeJohns in the Dave Gerr category of being an articulate and insightful engineering mind who's turn of phrase has helped me more in a few paragraphs than anything I've read in a decade.]

What I'm saying is that we shouldn't allow some grumbly, inarticulate and argumentative online presence to encourage us to ignore the fact that empirical experimentation as a part of layman's designs is a valid means of evolving a metal boat.

As regards the scantlings of the larger hulls, to my knowledge they are scaled- where a 30' is 3/16" a 50' is 3/8" or something to that effect.

I agree that the egg shell idea will fail if the impact is experienced in such a way as to overcome (as MikeJohns has explained I thought rather elegantly) the combination of local panel rigidity and shape stiffeness. What the Brent seems to miss, or choose to ignore, is that simply because this combination of momentum and collision has not yet resulted in much damage, that is little reason to believe in CANNOT happen.

Finally, back to building method as defining the hull form, the origami method severely limits the shapes of the waterplane and I still hope to hear from a practicing designer their impression of the performance aspects of this legacy form?

Cheers,

DanishBagger,
As regards the scantlings of the larger hulls, to my knowledge they are scaled- where a 30' is 3/16" a 50' is 3/8" or something to that effect. :eek:

The Dix 65 ft boat I had built, used 4mm plate across the WHOLE hull with 3mm deck.... This boat was built in 1991 and have sailed ever since across the globe and it shows how light a hull can be with proper scanting rules used wisely. This is the 65 Dix uses in his website.

DanishBagger,
It's an odd day when I find myself taking a stance more in support of the Brent than against! But I need to remark about the Origami method and boats at least in passing. My remarks are more about the idea of origami than it's practice by the Brent.

I'm not sure how much we disagree in the following, but I think I have to "expand" a bit.

First, these boats are strong and not flexible or flimsy and next their hulls do go together quickly almost regardless of your metal working skills. Not that makes much difference in the time to build a finished yacht.
Nope, it sure doesnt. I'm not saying (I hope not, anyways), that these boats are "flimsy". With the thickness mentioned, it better not be, but more about that later.

So:

This idea is not fully founded, its not wrong to be cautious and the Brent isn't very articulate in regards logical discourse so you'd be hard pressed to find out why that statement isn't as accurate as possible.
Well, the thing is, that in order for a flat panel to have rigidity, you either have to support it, or use a thick enough material to resist the flexing. Later in this post you mention 3/16" steel plate or heavier, which, no matter how you put it, is rather thick (and heavy), all in an effort to resist flexing. You seem to say, that because it's thick, it cannot flex or be fatigued? I think of that as overbuilding, simply because you could use much thinner plates, if you used "old-school methods", yet have at least as good rigidity. To me, that translates into "amateur job" (says the amateur).

These boats have an "analyisis and calculation" more in the traditional [wooden] tradesman's/boatbuilder's sense than on paper. The tradesman of old had Rules of Thumb and without bothering to submit them to an engineering examination the Brent has developed his own set of RoT; but only refers to them in obtusely stated arguments which I think cover the value of these lessons learned.
I'm not sure I understand the last part in that paragraph. However, with regards to the rules of thumb of boatbuilders of yore: Even "modern" boatbuilders have that. Wood-epoxy boatbuilders have that, as developed from the initial years of trial and error. Scantlings included.

In other words, having studied the Origami method and specfically the Brent's scantlings individually; I find there are good design and structural features that may be covered from other's view and honest examination by the Brent's poorly worded rants about his "metalmessiahship".

The hulls are 3/16" or heavier (as far as I know) and that, for a <40' boat begins to approach the StrongAll method wherein the interior structure is reduced in favor of heavier hull materials. What has not happened (by the Brent as far as he has published) is a formal structural analysis of the boats; BUTTTTTTT!!!
And he never will post such a thing.
With regards to the first part, I'm not sure I quite get what you're saying. As I understand Brents "designs" and the method itself, is that the heavier material is used to GAIN interior space, not the recerse, as you can use much lighter materials, and much less material by supporting the "shell" - especially considering the flat "waterplane" as you guys call it. What's worse about Brent's claims in particular is that he's claiming that there's no problem to build something, say, 60ft. Now, with that flat waterplane, more or less unsupported, you will have to go even thicker to resist the flexing.


With all that said, there are no instances of hull failure or even fatigue to call to question the method or the particular scantlings - design of framing of the existing hulls. It is embarrassing that the Brent refuses to find a more graceful means of making such a simple point- but there is the full history (perhaps archaic history of marine design) of boatbuilding to support concept that "tried and true" is valuable information.

The problem is, that even though there has been no failure up until now on his boats, doesn't prove they're seaworthy, and certainly not "close to bulletproof" (he didn't use those words, but that seems to be what he wants to convey.

I am not saying, as does the Brent in any venue he seems to attend, there is no room for improvement, no reason not to analyze or that these designs are the final word in metal marine forms.
I, on the other hand, aren't saying the method sucks per definition, I'm saying that the method is limiting in all sorts of manners, and that it's ridiculous to caim this method to be superior to "old school" methods. Speaking of which, I find the primitive way of building, and using extraordinary heavyweight scantlings to overcome poor engineering (or no engineering, in Brent's case) primitive as hell. Much worse than the overbuilding of old-school wooden boatbuilding (yes, that one was for you, Brent, if you're still lurking backstage).

All I want to point out is that we need to look closely at what is really being built - and not be distracted because one of the builders of this method is rude to a fault.
True. I only entered this discussion, because I grew annoyed with Brent's unfounded claims. I especially disliked his claims that his method was superior to anything out there, yet he utterly failed to show how that could possibly be. He only came orth with further - equally unfounded - claims to support the former. I am in no way, form or fashion trying to pass as an expert in these things (I'm not saying you're suggesting that - I just need to emphasise as much)

So, while I can't agree with the bombast and noise that passes for discussion with the Brent, there is validity to building boats that are guided by rules of thumb- especially if you're building the same one over and over.
Yes, there are certainly validity in building by rules of thumbs, but so far, "the Brent" (as you call him consistently, ha ha) has not given any rules of thumbs, nor has he shown the basis for his rules of thumb.

Am I discounting what MikeJohns has said? Not in the least, in fact I read those posts daily for a week being more informed each time I read. [I'd put MikeJohns in the Dave Gerr category of being an articulate and insightful engineering mind who's turn of phrase has helped me more in a few paragraphs than anything I've read in a decade.
I'm 100 percent with you.

What I'm saying is that we shouldn't allow some grumbly, inarticulate and argumentative online presence to encourage us to ignore the fact that empirical experimentation as a part of layman's designs is a valid means of evolving a metal boat.
Of course not. The problem is, that in order to develop rules of thumb, you have to have a lot of trial and error and a lot of thinking. Overbuilding by way of just using extremly much material is simply ridiculous in my eyes. Further, I doubt that a true layman (as in completely blank) would be able to build a seaworthy, safe, and lasting vessel without looking up things like scantlings (i.e. rules of thumb other people have derived from trial and error). Besides, in Brent's case, I would like to know things like vanishing stability and so on, since the things are build with such heavy scantlings I fear the worst, frankly.


As regards the scantlings of the larger hulls, to my knowledge they are scaled- where a 30' is 3/16" a 50' is 3/8" or something to that effect.
Yes, in order to resist flex/lack of rigidity. The problem is, that by using flat panels over such a length, the panel _wants_ to flex.

I agree that the egg shell idea will fail if the impact is experienced in such a way as to overcome (as MikeJohns has explained I thought rather elegantly) the combination of local panel rigidity and shape stiffeness. What the Brent seems to miss, or choose to ignore, is that simply because this combination of momentum and collision has not yet resulted in much damage, that is little reason to believe in CANNOT happen.
Exactly. I have to make the point at this stage, that by his own argumentation, apparently my pseudo-sandbagger must be stronger and more seaworthy than his steel boats ;)

Finally, back to building method as defining the hull form, the origami method severely limits the shapes of the waterplane and I still hope to hear from a practicing designer their impression of the performance aspects of this legacy form?
Me too.

Cheers,

Ta (trying to sound british, lol).

Brent Swain

Tom McNaughton of the yacht design school is an enginer with a good grasp of marine engineering too. I noted that he wrote a fairly damming critique of your design justification. I'd be interested in your reply to this. Which I pulled of another website. I know a lot of people here who have considered your designs have been put off by these sorts of comments.

Thanks


Quote Tom MacNaughton

Periodically someone will just decide that the transverse framing is "not necessary. They always come up with great sounding verbal rationalizations but have never actually done the math.
The amount of weight you can save by tailoring construction to save the absolute maximum in weight, including custom spacing the transverse frames and other transverse members is so minimal and the mathematics necessary to properly predict where you can reduce transverse framing is so complex that I am certain that no one advocating the elimination of transverse framing has actually done the math.

They are just building cheap, weaker boats.

One North American advocate [Brent Swain] has written a book which he told me "proved" his case, yet on buying his book I found there was no real structural analysis in it and the one piece of math in the book which applied to reducing framing was wrong.

There have been recent attempts to reinvent the construction method. Any reduction of the scantlings simply produce a boat less strong than the other methods. Naturally a rationale for this cannot be put in engineering terms. There it would evaporate.

The overall rigidity of the boat is largely dependent upon the framing. This leads into another argument. This one says that you can eliminate the framing by increasing the thickness of the shell plating. While this would, in theory, and viewed in isolation be true. It does not really work out because stiffness usually comes from thin deep frame members with high section modulus for their weight. Thickening a thin relatively heavy plate to provide the lost strength from removing the frames is very inefficient. The net result is that if you eliminate framing you about double the weight of the hull shell.

In an actual calculation comparing a normal hull framed both longitudinally and transversely with one that eliminated the framing the increase in weight of the metal structure of the vessel was 96%. Even disregarding the consequences for plate forming operations and welding operations of going to thicker plate, it should be easy to see that the large weight penalty is not acceptable because the performance of the boat will suffer terribly.
Do we really believe that these people are making the shell plating as thick as necessary to gain back the strength lost by eliminating the framing, given this weight penalty? I think it highly unlikely in view of their claim that they can reduce costs. Therefore should a metal boat be promoted as “frameless” you can essentially say that something is wrong.

A North American advocate [Brent Swain] has written a book which in one place compares the stiffness increase obtainable by using a thicker plate versus a thinner using an erroneous prediction of the relationship of thickness to stiffness. Presumably his entire system advocating reduced framing is justified by basing it on this erroneous calculation. There appears to be another interesting reason for this intense desire to justify reduced framing. We have noticed that all the structural members whose removal is advocated are the ones whose shapes are difficult to predict if you do not understand how to design the vessel with developed surfaces and produce patterns and plate expansions graphically such that every piece of the boat can be precut and can be set up and welded into a predictable shape.

Instead of this fully predictive system these boats seem to start out as scale hull plate patterns created by trial and error by cutting shapes and “folding” them until a shape is derived which looks good. Then the full sized patterns for the plates are scaled up for various sized vessels. However this trial and error system leaves no way to predict the shapes of transverse frames, watertight bulkheads, floor timbers that follow the shape of the hull and keel, etc. Interestingly enough it is these same members whose shape cannot be predicted using these methods that suddenly are declared “unnecessary”. At best this seems an exercise in self-delusion.
One final argument made for “reduced framing” is that if boats are composed of curved surfaces and that curved surfaces are stiffer and therefore don’t need framing. Let’s get real, even to figure the deflection on a simple curved beam of constant radius gets you into calculus. When you get into anything as complex as a boat hull with varying curvature in all directions, not to mention chines, deck edges, varying loads from ballast keels, large engines or rigs, the math pretty much goes off the charts. I just simply don’t believe that the folks I’ve seen advocating this as a reason to reduce framing have done these calculations.
Even with today’s computers and some pretty fancy and expensive software achieving any significant weight savings given the normal complexities of hull shape is quite unlikely even without considering some of the other factors which tend to make it difficult to save weight in real world hulls. Among these are the fact that without frames to stiffen the structures all the stress simply runs to stress concentration points where the hull may be reversing direction of curvature, be flat for hydrodynamic reasons, have some sort of chine or other corner around which the stress will not carry without some support.
Given all this the prediction of stress levels to sufficient accuracy in any given area to allow the reduction of scantlings on the basic of curvature becomes unrewarding and in practice is never done. My experience is that the people asserting that they can make such scantlings reductions, although speaking with great confidence and often with much disparagement of those who question them have not in fact done the analysis necessary to develop rational scantlings and are in fact just deciding to believe what they want to believe. One common characteristic of these promotions seems to be little or no space devoted to any real structural analysis of the relationships between methods. There seems to be a lot of space devoted to circular arguments saying that no proof is needed because only very stupid people living in the past could possibly not see the superiority of this new method. The evidence that these people are stupid is that they ask for the proof! These are “religious” arguments in that we are asked to “have faith” and those who doubt are castigated as lacking in the vision of the “true believer”. You will find us always on the side of “doubt” rather than faith.
We are always worried that we have made a mistake, have failed to see a possible failure mode, are using a model that is not as predictive as it might be possible to construct, etc. The “true believer” is unencumbered by doubt and therefore need never check for mistakes, worry about failure of imagination, etc.
We don’t buy into this and you shouldn’t either. In conclusion, do not be distracted from the lessons of real structural analysis by the promotional materials of these companies.

This is simply another repetition of the mistakes that builders have made over and over. I would suggest remembering an old principle of design: If structural analysis says a boat is strong enough it may be wrong, but if structural analysis says a boat isn’t strong enough it is probably correct.

End quote (Tom MacNaughton YDS)

Thank you Lyndon. Great find!

I couldn't help but laugh when I came to the part where he (too) were getting religious associations with regards to Brent's circular arguments.

Thanks guys
excellent reading:idea:

Flat surfaces? What flat surfaces? There are no flat surfaces on an origami sailing hull. This is where your mathematical theories fail ,as they are all based on flat surfaces. I've mentioned this many time in this debate.Re- read this until it sinks in.
Brent

Flat surfaces? What flat surfaces? There are no flat surfaces on an origami sailing hull. This is where your mathematical theories fail ,as they are all based on flat surfaces. I've mentioned this many time in this debate.Re- read this until it sinks in.
Brent

A very large radius is in layman terms an "almost flat" surface. Instead of us continueing to reread your nonsense, how about you backed said nonsense up with real analysis, numbers and fact, and did the exact same with everything you say is crap. Up until now, you haven't even been able to provide anything asked.

Hell, you haven't even been able to put forth even a some