Weed eater engine conversion

I was making the point that they can be build far cheaper than bought complete with very little effort or knowledge.Those bush cutter based motors can be purchased for around $125 from various sources online,or used to.A T10 prop from Youngs,not sure what they cost now,and a trolling motor mount from ebay.Should be able to do it for well under half price and a saturday's work.Used brush cutter or one that you have on hand would lower the cost greatly.

 

Maybe they can be built cheaper BUT that wasn't the question and NO I dont want to build one.

 

the one i built and posted back on page 88 of this thread is far superior to my island hopper outboard in performance but if i had it powder coated like the island hopper is it would cost more than what they charge. i used a honda gx35 motor with a 2year commercial warranty that goes for around 250 for the motor alone. there is no store bought prop that will work well unmodified unless u have the correct gear reduction for that prop. i can assure u that the island hopper outboard does not have the correct gear reduction for the prop they use

 

tractor prop

Hi buttales, I must be living right - I check here periodically for a solution to my design problem (marine prop in tractor) and viola! here you have a working prop.
As you are looking from stern forward is the prop turning Clockwise or counter? Is the propshaft something you added on to or the original (would you know the thread specs - I would need to use a thread coupler)?
Thank you in advance for any assistance, propfan

 

hi propfan, the prop spins clockwise when viewed from the back of the boat. when using a 2 gear gearcase such as the ryobi i used, it reverses the rotation of the motor compared to a mud style motor. i did use a regular tractor airplane prop but i mounted it upside down. u can get a apc 13x4 pusher props from tower hobbies and not have to turn the prop upsidedown. i also finally got my maruyama 1.9 gear ratio gearcase(took 2months and 150 bucks to get) but i havn't tried it out on the water yet.i also use a heavy duty clutch shoes from stanton that weigh twice as much as the stock honda clutch shoes. if all goes well i'm expecting stellar performance from this setup

 

buttales, if you're not happy with the Island hopper pm me a good price.

 

hey 3dog, i've cannibalized the drive shaft because the maruyama gear case takes the same splined shaft as the old motor did. i also used the kill switch and throttle cable as well. i will be building another outboard from that old motor but it will have the ryobi gearcase and made to fit into a hobie drivewell and not using the trolling mount bracket

 

Hey guys, I have a question.

Why not just use a electric trolling motor, and 69$ generator, and charger?

 

Because that would weigh a ton!
You would need a battery becuase a generator isn't going to put out 12 volts: 29 lbs (55 lb thrust trolling motor) + 32 lbs (Optima Red top starter battery) + 39 lbs (harbor freight generator) = 100 lbs

Erich

 

OK then, how about a small 2 stroke engine, 12 v alternator, and electric trolling motor?

 

Your getting closer, forget the alternator and the trolling motor!!!

 

Lol, what he said.

Just get a motor, add a shaft and prop and you're done. No sense in turning gas power into electrical power just to turn it into thrust. Cut out the middle man and find a lightweight motor, add a prop that's not too big or too small and you've got the ticket!

Erich

 

But the weed trimmer engine spins too fast, I bet a lot of power is wasted.

I bet the above setup delivers more thrust / pound of weight than the weed trimmer with a prop on it.

 

That's not actually the case. Having built one, a weed eater has a pretty good amount of power for how small it is. It's not for a boat that can handle a large trolling motor and heavy battery. It's for a small, 1 man boat where every pound of weight matters.

Check out some of my videos on my motor: Weed Whacker Boat Motor Playlist

Erich

 

I understand that it works,

I just have doubts over weather it could work better.

Those little air cooled engines aren't even designed to work at their maximum output, thats one concern; how long will it last?

What is the reason for the weed eater being such a good start for the project; just that it has a cable shaft?