Weed eater engine conversion

Im currently trying to design a way to drive my 12' pirogue with a weed eater engine i recently picked up for free. I know it probably sounds dumb, but I believe it can work. However, I don't know how to find out what size/type/pitch prop I will need. I am hoping to have direct drive for simplicity. I don't know the exact specs on the engine yet, but most weed eaters are around 30cc. I would estimate its power at 1HP at best. Any information is greatly appreciated, and let me know if you need more information on the engine/boat.

 

While I was searching for a site that I found a long time ago but couldn't locate tonight, I stumbled upon http://www.go-devil.com/ which might lead to some ideas, though their engines start at a 5.5 hp honda, so I guess they're more lawn mower engines then weed eater engines

There are lots of threads in rec.boats.buliding from the last few years talking about projects similar to yours (you can also search rec.boats.building through google groups). But I couldn't find many specific answers or sources for what you're looking for... mostly posts as people began their conversion projects.

Large RC model boats commonly have the size engine you're talking about though. Most often they're inboards but I've also seen them mated to miniature RC IO drives which was neat for a model. The converted weed eater engines go for around $200-250 as a kit for RC boatbuilders. Others I know have converted weed eater engines themselves for RC boats, but I'm not sure how much assortment of miniature weed eater props there is...

Isn't the noise going to drive you mad?

 

The engine is really not that loud, but anything beats paddling

It appears that this is the best way to mount the engine. The pull start, handle, and throttle trigger are all in great locations. the handle could be used as a tiller. I do see a couple of problems however. First, this is rotated 90 degrees counter-clockwise from the way you would hold it as a weed eater, which puts the fuel tank filler cap facing forward. Not a big deal, I could always just mount a new tank. This one is part of the handle, so I can't just remove it and rotate it. Another possible problem I see is the location of the spark plug. It looks like its just asking to get drenched, and short out. I'm thinking some sort of small shield to surround it should be sufficient, as this will never see high speeds. Other than that, the only real problems left are figuring out how to mount it to a transomless pirogue, as well as finding/making a suitable prop.

I have thought of one other thing, however. most weed eaters are designed so that the engine can be easily removed from the shaft, in order to change from say a trimmer, to an edger. An edging attachment has a gearbox at the bottom, at a right angle to the shaft, with some gear reduction. I may see if I can find one of these, and see what type of gear reduction it has. I'm thinking it might just be enough to be able to use a small trolling motor prop.

 

HI,
already made one my son found a 1.5 HP evinrude outboard on the sand bank opposite the house and as the top half was completely corroded away but bottom end was okay fitted a weedeater top to it with a centrafugal clutch and now have a outboard which will even drive the 3.5M IVB ..!!!!??
don

 

There are plenty of trolling motors with bad electrical motors to be had for free. Seems like the ideal setup to add a gas motor to. Check your local marinas or shops. I know we've thrown many in the trash since they are not worth fixing.

 

How could I use a trolling motor? I I thought the electric motor was in the 'pod' at the bottom of the motor. Badges65, do you have any pics of the motor? I thought about using an old intermediate and lower unit from an outboard, but I don't know how I could attach the weed eater motor to it, and have it drive the lower unit. Also, would it have to have a clutch on it? I thought the lower unit would give your forward, neutral, and reverse.

 

I thought it would be possible to hook up the flexible shaft to the electric lower unit.

 

Hi Ward,
will get some pics in a couple of days and also of another version of the use of a weedeater a 12V generator!!???
The only problem was marrying the output of the weedeater drive to the shaft of the outboard leg, but its a little beaut as just give it the tit and she drives swell no tit and in neutral. turn the whole motor 180 degs as in the normal outboard version for reverse.
don

 

Do you guys think I could simply use a trolling motor prop? I looked at a few at wal-mart, and the smallest one they have is about 6" in diamter. the pitch wasn't listed on the box. I'm thinking the little weed eater motor wouldnt have enough torque to swing such a large prop without some sort of gear reduction. I wish it would work though, because it would bolt right up to the outpout shaft for the weed eater.

 

Hi Ward,
here are the pics of weedeater conversions..

 

HI all,
sorry looks like it will only take one file att..
will have to post 2 more times..
don

 

last one
don

 

Who, the outboard looks awesome! It looks like it came from the factory that way. Thanks for the pics

 

Hi Ward,
forgot to mention that it is swinging a 7 inch 3 blade prop.
don

 

I would be interested in any info you guys might be willing to share on the weed eater/ out board idea.
thanks,
Bill