How to use a grass trimmer to drive boat

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beatsal

Joined Jan 21, 2018
325
I have a 27cc 2-stroke grass trimmer. It bends at the trimmer end by almost 90 degs - seems an ideal bend to attach a boat prop. Looking for ideas as to how to attach it to a boat, which boat to buy etc.
 

strantor

Joined Oct 3, 2010
6,112
those spin at very high speed. Probably equivalent power to a trolling motor but those are much lower speed. So I think you would need a very small propeller with a very fine pitch. A trolling motor proppeller I think would not work; it might work for a while but I think it will bog the trimmer down too much and put too much load on it, eventually burning up the clutch. I don't know what kind of prop to recommend but I would say that a kayak or small dinghy is all it's good for (assuming you can find a good prop). Something like this:
 

Papabravo

Joined Feb 24, 2006
19,248
I have a 27cc 2-stroke grass trimmer. It bends at the trimmer end by almost 90 degs - seems an ideal bend to attach a boat prop. Looking for ideas as to how to attach it to a boat, which boat to buy etc.
That has got to be about the stupidest idea I've ever heard of. What is with the urge to nail two things together that have never before been nailed together? So, do you imagine your friends with think you are Joe Cool? Puh-leeze.
 

strantor

Joined Oct 3, 2010
6,112
That has got to be about the stupidest idea I've ever heard of. What is with the urge to nail two things together that have never before been nailed together? So, do you imagine your friends with think you are Joe Cool? Puh-leeze.
That seems unduly harsh from here. Are you familiar with long tail motors and mud motors for shallow waters and mud flats? They aren't cheap and also often resemble large weedeaters. If you could make one from a weedeater then I think, if money is the limiting factor, this could enable to have something and do something that would otherwise be unattainable.

That said, I don't think it would work very well. Worth a try if you've got the stuff, but with managed expectations.
 

Papabravo

Joined Feb 24, 2006
19,248
That seems unduly harsh from here. Are you familiar with long tail motors and mud motors for shallow waters and mud flats? They aren't cheap and also often resemble large weedeaters. If you could make one from a weedeater then I think, if money is the limiting factor, this could enable to have something and do something that would otherwise be unattainable.

That said, I don't think it would work very well. Worth a try if you've got the stuff, but with managed expectations.
I am familiar with those devices. Nowadays, if you can't afford to buy what you need, you probably can't afford the wherewithal to fabricate an acceptable substitute from junk you have laying around. This is especially true if your time is worth anything. Once upon a time when TV's were expensive and labor was cheap, a company called Heathkit, made money selling build it yourself TV kits for less than the cost of a new assembled one. Heathkit went out of business decades ago because assembled TV's are cheap and labor is expensive. Are there any fabricators with the resources and the knowledge to do this? Maybe. So if this is such a great idea, where are they?
 

strantor

Joined Oct 3, 2010
6,112
I am familiar with those devices. Nowadays, if you can't afford to buy what you need, you probably can't afford the wherewithal to fabricate an acceptable substitute from junk you have laying around. This is especially true if your time is worth anything.
You make a good point, and it's one I've made myself many times. My instinct is usually to DIY a solution rather than buy one, and I've been slowly abandoning it over the years. For thing I actually need anyway. Sometimes I just want to make something though. I think all here can identify with that a little? Otherwise why would we be on this forum?

I wonder though, to what degree this is a perspective unique to developed western civilization. TS didn't state their country but if it's Myanmar or something, the cost/benefit equation is probably different.
 

Papabravo

Joined Feb 24, 2006
19,248
You make a good point, and it's one I've made myself many times. My instinct is usually to DIY a solution rather than buy one, and I've been slowly abandoning it over the years. For thing I actually need anyway. Sometimes I just want to make something though. I think all here can identify with that a little? Otherwise why would we be on this forum?

I wonder though, to what degree this is a perspective unique to developed western civilization. TS didn't state their country but if it's Myanmar or something, the cost/benefit equation is probably different.
There are many things that are not amenable to the economies of scale for things that can be mass produced. For example, if the thing you need costs $25.00, but the shipping cost to get it where you need it is $250.00 then maybe a bit of elbow grease will fill the bill. I do not think that is case here since a boat motor and a string trimmer should have approximately the same availability level pretty much anywhere.
 

MrChips

Joined Oct 2, 2009
27,101
I have a 27cc 2-stroke grass trimmer. It bends at the trimmer end by almost 90 degs - seems an ideal bend to attach a boat prop. Looking for ideas as to how to attach it to a boat, which boat to buy etc.
Why do you want to do this?
You select your boat to suit your paddle? I would think that it is the other way around.
 

Reloadron

Joined Jan 15, 2015
6,950
I have a 27cc 2-stroke grass trimmer. It bends at the trimmer end by almost 90 degs - seems an ideal bend to attach a boat prop. Looking for ideas as to how to attach it to a boat, which boat to buy etc.
Isn't that a little like putting the cart before the horse? Really I agree with everyone else in that a trimmer is designed as a high speed 2 cycle engine, really not designed as a trolling motor for a boat.

Ron
 
Hey, totally out of my expertise but it just sounds like a fun project. (Also potentially dangerous if you don't handle the thing carefully!) If it's just for fun, it doesn't need to make economic sense. I'm enjoying the conversation & video. If this is a serious goal, good luck!
 

panic mode

Joined Oct 10, 2011
2,298
the video is silly. the drone of the weedwhacker got drowned when submerged indicating huge imbalance in load. that thing cannot last long so try better matched prop and maybe have backup paddle just in case. have fun...
 

SamR

Joined Mar 19, 2019
4,394
The problem with the Weed Eater is lubrication. The end of shaft bearing is not waterproof! Nor is it designed for the increased load of a prop. Put a prop on it, jump in a canoe and see for yourself...
 
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