Weed eater engine conversion

[wac m trac m]

I snapped my shaft today...uggghh. I was navigating some shallow water and turned the prop right into a rock at full throttle. "snap"

Back to the drawing board..lol

[Mark Wo]

Yep, that's me in the picture John posted. I'm now a famous internet celebrity (not that kind) While the motor is stock like John mentioned, the shaft and other parts required some minor work. If I can do it, anyone can do it. I followed John's advice on the bushing/grease seal unit (and other suggestions) he posted earlier. The rest was trial and error and I still have a couple of things I'm trying to fix.

Without much effort I was able to get 6.2 mph measured on the gps. I don't think more power or torque would push me any faster. With this motor I was also able to easily push through weeds without the thing bogging out.

My first attempt was to follow Ripped Off's design. I found that the Bolen's motor purchased at Lowe's wasn't up to the task. It was about 90% there but the 31cc motor didn't have enough punch to work consistently and in all conditions. It was quickly abondoned for the duropower unit found on the web. One other very nice feature of the duropower unit was it's quietness. Mucho better than the Bolens and other inexpensive chinese motors.

It was a fun project and I appreciated the information shared here by Ripped off and from exchanges between John and myself. If you are hesitant about building one of these, don't be. Easy peasey.

Mark W

[jkwhite]

Mark...thanks for that info. Are you running the 52 cc engine? My plan is to order the 52 on monday. Also, did you use the prop from Young's (the size that rippedoff recommended?

And, thanks for everyone that has answered and thrown in some info. It has really been helpful.

[alexlebrit]

I'm almost tempted to start a new post, but I thought I'd pop it in here as I have no real info to give.

Everyone's concentrating on weedeaters here, and I can see the logic, but what about other ic power tools? I've been eyeing up my old chainsaw for a while now, and combined with things I've been reading about pedal powered boats was wondering if anyone's considered a chain driven system - a bit like this (but not twisted of course).



And of course the prop would be suited to the engine's performance.

Second thing - What's the handling like on a long-tailed weed-eater boat? I imagine it'd need quite a large area to turn round, or are people using rudders?

And third - And this springs slightly from the second, has anyone used a weedeater conversion as part of an inboard drive? Then you could have a rudder although of course you lose the ability to lift the prop, but as weedeaters tend to have tiny props anyway I'm sure it'd be possible to protect it with a skeg or skegs.

[Mark Wo]

The T-10 that Ripped off used would not work on the Duropower unit due to the differencces of shaft sizes. I think John had a T-12 and I ordered one of those and I ordered a T-4. The only differences between the two is in the way they attach to the shaft. The T-4 was an easier way to attch but hte T-12 might be a better attachment method.

I don't think Duropower will be open on Labor Day.

As far as turning - it isn't like an inboard or outboard motor that is for sure. The shorter you can make you tiller, the shorter the :throw" required to turn sharper. It the pictuer John posted above, that motor had no skeg and it did not turn at all. I also had some issues with my tiller not being secure and a couple of other things but the previous motor built while it didn't run consistently it turned wll.

Mark W

[wac m trac m]

Why would you make it pedal powered? You could just paddle. The whole point of this project for most of us is the use it to get back in the marshes to duck hunt. The biggest problem is shallow water and weeds. The weed eater moter wont get you from point A to point B but it will get you most of the way there. It's way better then paddling or peddleing. The prop at the bottom of the boat would hit bottom almost everwhere I hunt/fish.

[alexlebrit]

Originally Posted by wac m trac m

Why would you make it pedal powered?

I wouldn't, it was to illustrate my point about using a chainsaw as engine instead of a weedeater that was all. Remove the pedals/crank etc, and put chainsaw in their place (also remove the twist in the chain cos we can just turn the saw round by 90°) You've then got an engine at the top and a prop at the bottom with a chain connecting the two. Which is vaguely like an outboard motor. The huge advantage as far as I can see with chainsaws is that they almost all have some form of clutch mechanism, usually a centrifugal clutch, so that you can start and idle the motor without the prop going round. Weren't some people having problems with the prop bogging the motor down and even stalling it?

Might not be the best for specific duckhunting conditions, but there's people looking at converting IC powertools for other purposes too.

[ben2go]

Originally Posted by alexlebrit

I wouldn't, it was to illustrate my point about using a chainsaw as engine instead of a weedeater that was all. Remove the pedals/crank etc, and put chainsaw in their place (also remove the twist in the chain cos we can just turn the saw round by 90°) You've then got an engine at the top and a prop at the bottom with a chain connecting the two. Which is vaguely like an outboard motor. The huge advantage as far as I can see with chainsaws is that they almost all have some form of clutch mechanism, usually a centrifugal clutch, so that you can start and idle the motor without the prop going round. Weren't some people having problems with the prop bogging the motor down and even stalling it?

Might not be the best for specific duckhunting conditions, but there's people looking at converting IC powertools for other purposes too.

Your idea could work.All chain saws made now days have a centrifugal clutch.All you would need is a chain and lower sprocket to match the saw's sprocket that gives the correct gear reduction for the prop.I wouldn't use the saws cutting chain.That would be disasterous if it broke and could sink certain boats.Not sure what gear reduction would be needed.Some chain saws have a built in gear reduction.

[alexlebrit]

No, using the saw's own chain would be a bit mad really, I have no idea what rpm my chainsaw is doing, I guess I could measure it somehow, I've bodged together a cycle computer revcounter before, so I might try it again, if I can't find it from the makers.

And yes either use the existing top sprocket or replace it with either a different (bike?) sprocket or a belt drive even?

[Mark_in WI]

I want to say thanks to everyone who posted. I think I will try one of these when I find a weedwacker to use. money is tight so i, like many, have to try this on a shoestring budget. While looking for different ways to mount my trolling motor I came across this site at duckhunting chat and I'm glad I did. I also found a guy on Youtube a guy that used his cordlessdrill, a shaft, and a prop to move his dingy. Here is the youtube page http://www.youtube.com/watch?v=NOTwJRnmrTY. It works but not quite what i am looking for.
Thanks again
Mark

[Orphanedcowboy]

I am getting in a little late on the mount discussion, but here is what I did to control depth:







Also here is my mounting plate for a little would boat I am building:




I have a lot of catching up on this thread, John, Wac M, you guys are doing some fabulous work, keep it up!

[John O`Neal]

Latest project (gear reduction Conversion) is almost finished. Two hp engine running through a 5/1 reduction max prop speed is around 1750 rpm. Any prop suggestions????

[Orphanedcowboy]

What direction clockwise or counter clockwise?

I have a clockwise rotation prop with a 3/8" diameter mounting hole, custom modified prop you can have, it was originally for a British Seagull outboard:

[John O`Neal]

Cowboy ; The rotation is clockwise and my shaft is 3/8" stainless. I would certainly give it a try . I can always return it to you if it didn`t work out. Thanks for the offer.

[Orphanedcowboy]

PM me your mailing address and I'll drop it in the mail to you