Electric Sculling Drive.

[kjell]

Electrical Sculling Drive with forward and backward propulsion. (Prototype) For small Boats
Kjell

[timgoz]

Hi Kjell,

What application do you forsee for this drive that a prop drive could not do in a simpler & more reliable manner? Just curious.

Take care.

Tim

[kjell]

This is the first prototype. I am installing it in a model boat and the video I will show will demonstrate how good or bad it is.
Kjell

[Frosty]

I would say that what you have there is a Kinda surface drive.

Ive been saying this all along that a surface drive propeller is a rotating sculling device.

If you imagine a surface prop in very slow motion does not each blade dip into the water and scull along and then out of the water and then the next blade comes in.

[kjell]

I don’t know the Kinda surface drive. My Sculling drive is using a Wiggle Drive to obtain the Sculling movement.
Kjell

[kjell]

I have now tested the Scull Drive with good result. See the video.
http://www.youtube.com/watch?v=XoBtz4cdojg
The Sculling arm and tail is made of Carbonfibre.
Kjell

[Landlubber]

kjell,

Hey that is terrific, everything old is new again! Just love it! Thanks.

We once moved our dinghies that way, till small outboards came along.

Which reminds me, why do people today face forward in a dinghy as they motor away from their yachts on the mooring,..... it is because their yachts are so ugly!

[Frosty]

If you had four of those blades (or more) and rotated them instead of using the same one backwards and forwards you would have a surface propeller but non cavitating or airiating.

You've obviously put a lot of work into it.

The only problem is the stop and start of the mechanism, whilst it is stopped ready to go backwards it is doing no work.

[lorejas]

Indeed, when reversing the movement, the drive does nothing.
But drive does not consume power at that moment.

The surface drive consumes power all the time, but part of that power is wasted bij lifting and pushing the stern of the boat.

So Kjell's system will be better where efficiency is important : electrically driven boats.

[Frosty]

It may be using less power at the reversing moment but thats because there is no work being done.

If there were two paddles attached in such a way so that wasted energy was consumed into motion.

[kjell]

The propulsion produced by an oscillating tail is different to a rotating propeller. The propeller produce a continues thrust, limited by the cavitation. The pulls propulsion has no problem with cavitation and can use a more efficient AoA.

KJELL

[Rick Willoughby]

Oscillating foils are very complex to engineer to get efficiency much above 50%. On the other hand it is not hard to get rotating foil (propeller) efficiency above 80%.

If nature had the equivalent of a shaft and bearing we would see birds and fish propelled with rotating foils because they are a more efficienct form of propulsion.

On the other hand if oscillating foils (wings and tails) were more efficient we would see boats using flapping tails and aeroplanes using flapping wings. They don't because they are complex to engineer and inevitably less efficient.

Rick W.

[kjell]

Hi Rick.
I have been looking to your nice web site. You have been working hard with your projects. May I comment two details on your tail experiments? The oscillating foil you are using is not the most powerfully tail propulsion. No fishes are using this foil movement for fast swimming. If you try to eliminate waves you must start to combine the flapping frequency to the boat speed.
Kjell

[Rick Willoughby]

Hi Rick.
I have been looking to your nice web site. You have been working hard with your projects. May I comment two details on your tail experiments? The oscillating foil you are using is not the most powerfully tail propulsion. No fishes are using this foil movement for fast swimming. If you try to eliminate waves you must start to combine the flapping frequency to the boat speed.
Kjell
Kjell
The wave drag on my latest hulls is minute (thanks to Godzilla) so no need to eliminate it because it would be a waste of effort. So my propulsion system does not need to cancel wave drag.

If you could work out ways to eliminate/reduce viscous drag with a simple solution it would be a significant development and this would be of interest to me and most of the boating world.

I developed oscillating foils till I understood the science and then determined you could not do better than a rotating foil.

When you can show hard data on efficiencies in the high 80s to low 90s you might have something that is more than curiousity value. I agree that there could be merit in getting wave cancellation for a short hull but I would need to see proof in the form of hard data.

Rick W.

[kjell]

Rick

Have a look to this web site

Dr.Evgeny Sorokodum

http://www.vortexosc.com/modules.php?name=Content&pa=showpage&pid=11

Kjell

[lorejas]

Rick,


Here in Europe it's hard to find a good propeller.
Can you give me some adresses i an contact for a propeller diameter12"
(0.305 m) and a pitch of 9 " (0.229 m ) with the highest efficiency at 400 revolutins/minute?
Up to now, i found efficiencies of only 63% in seawater of 25 °Celsius.
Thanks,
Lorejas,

[Rick Willoughby]

Rick,


Here in Europe it's hard to find a good propeller.
Can you give me some adresses i an contact for a propeller diameter12"
(0.305 m) and a pitch of 9 " (0.229 m ) with the highest efficiency at 400 revolutins/minute?
Up to now, i found efficiencies of only 63% in seawater of 25 °Celsius.
Thanks,
Lorejas,

The most important requirement for a propeller is that it is matched to the application.

If you give me details on the application like the hull shape, speed and power I can work out the best propeller and tell you what efficiency to expect. You then have to find or make a propeller that is as close to the best as you can get it.

By specifying the diameter and pitch you are likely to be condemning the design to sub-optimal.

I can provide detail fabrication procedure for low power props if you cannot buy a suitable one. You need to be able to weld to make it.

Rick W.

[lorejas]

Rick,
I really appreciate your quick answer.

I have a 5 meter electric driven boat, deplacement 0.250ton, waterline of 4.5 meters. Electromotor has the highest efficiency at 400 rev/minute.
I'am trying to improve the autonomy of the batteries.
The 12/9 dimensions are the actual propeller.

Thanks for your cooperation.


Lorejas

[Rick Willoughby]

Economic speed is likely to be under 5kts.

Have you got a photo of the hull?

If no photo then what it the waterline maximum beam?

Is it an efficient low speed hull or is it designed for planing with a flat transom?

If it has a transom how deep does it sit in the water at rest.

I need to be able to model the hull so I can produce a drag curve.

Rick

[kjell]

Hi Lorejas.
Welcome to my thread, your problem is not a sculling problem.
If you give me the HP or KW of your electric motor and tell me if your boat have narrow stern or wide flat stern I can tell you what propeller you need. I have working with propeller calculation for the last 35 years and I have my own program to make this calculation.
Kjell

[Landlubber]

kjell,

35 years of prop calc, would you be prepared to share your program with the world at large, or simply post a copy here, I promise not to tell anyone.

I have used the Propcalc that is from this site, but it does not necessarily agree with my physical use of props we use. It is close, but not exact, not that prop calculations are ever exact.

ta.

[kjell]

Hi Lorejas.
I f you have the PROPCALC program you are a lucky person. This is one of the best propeller program, based one the Bp-Delta method. 100% exact propeller calculations not exist. Manu time it is a question of interpretation. (If you have a violin that doesn’t mean that you understand music.)
Kjell

[kjell]

The Scull Drive can give better thrust thanks to its big flapping area and the possibility to a use higher AoA without the cavitations risk.
Kjell

[Landlubber]

Kjell, yeah mate but a player piano still plays music, so too does the program, so the ansswer is, that there is no answer.

Now when you recommend a prop to a customer, and he comes back sayong it is no good, what next. Have it repitched, diameter made smaller, who pays the slipping fees etc etc.

Come on fellas, this is very difficult. There is no simple answer.

[kjell]

Hi
It was not my intention to offend anybody with music example.
To calculate a good marine propeller is very difficult. Most new boats have the propeller badly calculated with the result of overheating engines and not reaching the offered speed. As Marine engineer it was my job to modify propellers. Before starting to modify you must understand how propeller works and know how to calculate them. The difficulty is to obtain the right numbers to introduce in the propeller calculator. The max efficiency for a marine propeller is 74%.
Kjell

[Landlubber]

Yeah kjell, it certainly is a difficult problem. We have been doing props here for the same years actually, all I can go on is what worked in the past for a certain type of boat and setup underwater, I have never found anyone that can be spot on from an untried design (not saying it cannot happen, just that I have never seen it). We seem to get ours OK as we basically do trawler stlye boats, and they really are very similar underneath.

My heart bleeds for you doing it as a profession! All the best.

[kjell]

Landlubber.
You are right. Many new bots are equipped with the wrong propeller. The main reason is that the naval architects don’t have the real weight of the boat and the engine power is not right. To be able to sell the boat they promises a boat speed that can not be archived when the boat is full loaded with water, fuel and personal equipment. With the PROPCALC program it is easy to verify if the propeller is right or not. For Displacement and Semidisplacement hulls the program is very accurate. For Planing hulls it is more critical do to different hull types. Knowing the LWL. weight and the SHP it is easy to verify if the boat is able to plane. Planing starts at SL-Ratio 2.9 – 3.0
Kjell

For any question about PROPCALC contact me at
kjellgood@gmail.com
You are welcomed.

[kjell]

I have done a video of the test to se how the scull drive works when you need to maneuver the boat.
http://video.google.es/videoplay?docid=-1656067526827705858&hl=es

Kjell

[mdatrpz]

Kjell, It's good to see you are still alive and kicking.

We corresponded with Kim Prentiss down in AU.

Now, it seems israel is taking the lead with wingsails.

Hope you are doing well.

Mark Diener
Florida, USA

[DanishBagger]

I wonder if this sort of drive will be a good idea (even with the energy efficiences people say there are) in ice: No superfast moving propeller to be damaged?

[kjell]

I wonder if this sort of drive will be a good idea (even with the energy efficiences people say there are) in ice: No superfast moving propeller to be damaged?

Here in Malloca I have no way of testing the Scull Drive in ice but the next time I are going to make a test I will fill the test- pool with small pieces of ice and I will let you know the result.
Kjell

[DanishBagger]

I don't think you can tell from that. I guess it's better than not testing at all. But it looks like the shaft will be the one being damaged (if anything). It would be nice, though, to see some pictures of it in ice – even if just in a pool.

How fast does it swing – how many oscillations would you gather per minute – I mean the "life-size" one (I'm assuming the small one oscillates faster)?

[kjell]

The idea with the Scull-Drive is to use it on small boats, not on ice breakers. The scull frequency will not be very fast.
Kjell

[DanishBagger]

The idea with the Scull-Drive is to use it on small boats, not on ice breakers. The scull frequency will not be very fast.
Kjell

Haha, I wasn't talking ice breakers, I was talking small (ish) motor boats –*slow moving troller types and small fishing vessels. Nothing huge.

[Kay9]

Would be kind of cool seeing a CG Icebreaker with swim fins.

:)

[kjell]

Kjell, It's good to see you are still alive and kicking.

We corresponded with Kim Prentiss down in AU.

Now, it seems israel is taking the lead with wingsails.

Hope you are doing well.

Mark Diener
Florida, USA

Hi Mark.
Are you still connected to any Wingsail project?
Kjell

[kjell]

The Sculling future can change in China.
Kjell

[Landlubber]

Sorry mate,

Love the artwork, but if it cost money, you have no chance in China.

http://i218.photobucket.com/albums/cc8/Photobucket_pic/ScullingBarge.jpg

I took this pic just last week, the whole boat would have been cheaper than your battery!

There is NO pleasure boating industry in China, simply because there is no where to use them, and most of the people could not afford to run one even if they were given it. They earn a dollar a day........and have a wife and kid to feed.

[kjell]

My Scull Drive is only a prototype and not designed for poor fishermen’s. The idea is to make Sampans for tourist’s trips in Hong Kong and Shanghais harbours with the same standard as the Venetian gondolas.
Kjell.

[Landlubber]

Oh well, good luck.

[groverdamascus]

Electrical Sculling Drive with forward and backward propulsion. (Prototype) For small Boats
Kjell
Hi Kjell, I'm new here, have you ever tryed driving one of your fishtails with an oscillating wind vane? flapping in the breeze, yanking the fishtail back and forth like?