godevil on canoe

[fishon91]

i have a 14 ft. canoe, it's very stable, i hunt ducks out of it all the time. i was seeing how some people would take weedeater engines and turn them into mud motors. i would like to do this but not sure how good it would work. i don't think it would tip, but would it be able to poush it? i read that anything less than 15 horsepower would bog out when the prop is set in the water.:confused: any ideas or suggestions are greatly appreciated.

[kengrome]

Maybe less than 1.5 HP, but I don't even believe that. It takes the right propeller to go along with the motor, and I think most people do not use the right propeller when they make these things ...

[fishon91]

so i would need a smaller prop, right?

[holychoad]

I just was asking the same question, the way i would go about it is you would have to take the existing shaft because it is springy like then you would have to weld on a steel shortend one, the question i had was how do you atatch prop and what kind of a pitch on the prop would you want that would make a big diffrence on how the boat planes out and how much more or less power you would have. You would think it would be enough power either way because an average canoe ways like 50-70 pounds maybe ?/.

[kengrome]

so i would need a smaller prop, right?

Maybe smaller in diameter, or maybe the same diameter but with less pitch. You might have to experiment a bit.

[Rik]

I think you will need to find a high helix propeller like they use on a Mud Devil drive unit to work best in your environment.

There is no substitute for HP, so the larger more torquer the motor you can find the better.

A lot of the boats are narrow that they use in the Jungles of Brazil so your Canoe should work after you modify the transom to mount the engine/drive assembly to.

[masalai]

I have seen 9.9hp hi-torque outboards happily push 2.5 tonne yachts out of harbour using less than full throttle for the 4 knot speed limit. Duck hunting may be a bit noisier with an engine though, but to get to the shooting area a 9.9 would be more than enough.

[Rick Willoughby]

I can do 12kph with a 150W engine using the right prop on a 24ft boat. The petrol motor will deveop much more than this but your canoa will be limited by its length and beam to maybe 10kph unless you get to something like 3HP or more.

You would get best results with a speed reduction to the prop but it does not matter much because a prop made out of twisted steel will push you at hull speed using the little motor. Having the prop shaft mounted off the side of the hull will not make much difference. It will only need a tiny amount of steering correction to offset the off-line thrust.

Rick W.

[kengrome]

I have seen 9.9hp hi-torque outboards happily push 2.5 tonne yachts out of harbour using less than full throttle for the 4 knot speed limit.True, those high-thrust engines are geared low and spin relatively large props, so they are expressly designed to push a lot of weight at slow speeds using low power.

I think a similar approach on a canoe will work nicely using a grass trimmer engine that's only putting out 0.5-1.0 HP, but the gearing would have to be something like 5:1 or maybe even 10:1 to get the RPM's down and the torque up enough for a reasonably sized prop to be used. If the RPM's are too high the prop must be so small that it won't be pushing on enough water to move the boat in 'draggy' conditions.

This reduction might be easy and cheap with a belt drive system, but it requires someone to design and build it. Belt drives are not known for their use in outboard installations although I don't see why they couldn't be used in place of a drive shaft and gearbox. I've heard they have some pretty strong, thin, waterproof toothed belts these days.

fishon91, in your original post you said you want to make a "mud motor" out of a grass trimmer. I do not have any personal experience using a mud motor or fishing in your conditions, so I would like to ask:

Is your canoe always floating in water when you're fishing or moving from place to place? Or do you actually have to run on top of (or through) the mud in some places? How thick is this mud? Is it mostly water with a brown look to it, or is it real sticky thick mud?

The reason I ask is because if you have to run on top or through the mud, that mud will probably create much more drag than plain water. In this situation it is possible that a grass trimmer engine will never have enough power to push your boat in the conditions where you're using it no matter how you gear it.

[Rick Willoughby]

i have a 14 ft. canoe, it's very stable, i hunt ducks out of it all the time. i was seeing how some people would take weedeater engines and turn them into mud motors. i would like to do this but not sure how good it would work. i don't think it would tip, but would it be able to poush it? i read that anything less than 15 horsepower would bog out when the prop is set in the water.:confused: any ideas or suggestions are greatly appreciated.

I had another thought on your propulsion system. Why not get a 300W geared scooter motor USD45, a 24V controller USD18, a couple of 12VA AGM batteries or bigger USD25 each; weld up some twisted steel on a 3/8" shaft and away you go. Could expect 8 to 10kph. Silent running for a range of 5 to 10km depending on speed. More range with bigger batteries. Can recommend TNC scooters for gear. The geared motor revs just a tad slower than ideal but will swing a much larger prop than direct drive on a weed wacker.

Mount the motor off the side forward of centre on the hull with the prop shaft supported by an angled strut at the stern. Work on a prop about 16" in diameter using 1.5" by 1/8" flatbar. I can tell you how to twist if you need. If you want to get really serious you could also shape it. This will be more efficient than a tiny prop spinning at a guzillion rpm.

I have attached a video of a cat that does 9kph with this set up. The cat would have about the same drag as your canoe.

Rick W.

[fishon91]

i might go through some thin mud sometimes, but mainly through thick lily pads, if not open water, i think the scooter idea could be much better. i probably don't know waht i'm getting into considering how little experience i've had with engines. and with the money situation i'm in it will be a while before i can even get involved with this. thank you very much for the info though. i would love to give it a try eventually and be able to go a little farther without so much struggle in my canoe. i also love to make my own stuff, another reason i want to try it. thank you

fishon!!

[John O`Neal]

Here is a neat little hand held propulsion device that appears suitable for canoe/ kayak applications. If you do a search (Whippella) on U-tube there is a demo. video. Quite impressive. Try Whippella "whipper snipper" prop attachment.

[Rick Willoughby]

That is a clever design. The shrouded prop is one way of getting reasonable efficieny with the small, high speeed prop. Very simple.

However - noisy, smelly, limited range and slower than pedal or paddle power that keeps you fit and does not consume liquid hydrocarbons.

Rick W.

[grob]

Rick,

What does shrouding the prop do for efficiency?

Gareth

[Syed]

I am not in favor nor against the shrouding, would appreciate the experienced views on;
http://mb-soft.com/public/ductprop.html

[John O`Neal]

[QUOTE=fishon91;178734]i might go through some thin mud sometimes, but mainly through thick lily pads, if not open water, i think the scooter idea could be much better. i probably don't know waht i'm getting into considering how little experience i've had with engines. and with the money situation i'm in it will be a while before i can even get involved with this. thank you very much for the info though. i would love to give it a try eventually and be able to go a little farther without so much struggle in my canoe. i also love to make my own stuff, another reason i want to try it. thank you fishon!![Quote]A
As a duck hunter myself I speak from experience on propelling a long narrow boat. My layout boat is 13ft 6" . I use several different motors during the season depending on where I hunt and what restrictions are in place. ie (no gas motors allowed). I use a Minn Kota trolling motor 75lbs with battery, or a Cruise n Carry Model 6600 air-cooled outboard 12lbs, or my favorite and the most versatile, a Weed-eater mini-longtail conversion ( pictured) about 16lbs. The least desirable being the trolling motor due to weight and limited battery range. Last season I followed a hunter out of the marsh who was in a Tote Boat (a version of a canoe) he was using a curved shaft weedeater with a non-ducted Young`s propeller on the end. He used it like a powered oar. He certainly wasn`t slow and appeared to have a high degree of control. In the weedy areas he would just lift the prop briefly out of the water and it would throw them off. I think the YouTube video Whippella and Finn Kayaks will assist you in making a decision on which direction to pursue.

[Rick Willoughby]

Rick,

What does shrouding the prop do for efficiency?

Gareth

Gareth
Not as much as I thought initially after doing the numbers. Depending on loading condition the efficiency for the prop shown could go from 58% to say 62%.

The shrouding in this case provides a measure of safety as well as the thing would be quite a weapon.

Rick W.

[grob]

Gareth
Not as much as I thought initially after doing the numbers.
Rick W.

Rick,

Thanks for that, do you have any references for this calculation, or do you use a piece of software?

Thanks

Gareth

[Rick Willoughby]

Rick,

Thanks for that, do you have any references for this calculation, or do you use a piece of software?

Thanks

Gareth

Gareth
I have my own prop analysis software only because I can do all sorts of manipulation with different foils. It does not give results much different to JavaProp:
http://colaco.freeshell.org/mhepperle/javaprop/jp_applet.htm

As downloaded, the options are set for air but you can change them to suit water.
Density for saltwater is 1025
Viscosity for water is OK at 0.0000013

You have to select the type of foil. Most boat prop blades are thin so I usually use the MH 9.8% 500,000 for bigger/faster boats and the E193 100,000 foil for smaller boats. You can adjust the AoA to get a suitable chord.

I have attached the screen dump from one of the calculations I did for the Whipella. Note that there is a checkbox that can be ticked to have with and without shrouding.

Effective shrouding will eliminate induced drag so it is particularly effective in heavily loaded applications.

As far as the boat goes conserning speed and power, I just guesstimated the speed and drag by looking at the video. I was only interested in the relative performance of the shrouding.

I have seen loading conditions where shrouding has had a dramatic increase in efficiency. Better than 10% gain in efficiency. This gain is offset a little by the extra drag of the shroud.

JavaProp provides a primarily anylitical result based on the underlying physics rather than relying on empirical data so it gives good understanding of what is going on if you care to work through the various analysis tabs.

Rick W.

[masalai]

And he hasn't even cleaned the weed growth off :D