Weedeater conversion as primary propulsion?

CampbellM

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Jan 13, 2014
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I've read a lot about weedeater/mud motor conversions but I'm not interested so much in the how-to as some much more general questions about these types of motors in general. First, a little background though. I have a 14' inflatable boat with a built-in wood transom that is rated to take up to a 10hp 2 stroke motor or an 8hp 4 stroke. So far I use it with a 55lb thrust trolling motor but would like to add some range by getting a gas outboard. I don't have a whole lot of cash to spend, otherwise I'd probably just buy a new Honda or Tohatsu 8 or 10 hp motor. Also, I stick to mainly lakes and rivers, many of them very shallow and choked with rocks, logs, and other underwater obstructions. I've already broken my trolling motor bracket twice because the motor hit a log or rock.

I'm currently ordering a new mount/bracket and plan to get that fixed over the winter. The weedeater/mud motors seem to be a good solution for shallow, obstruction-filled water. I'm not really much of a fisherman, more just wanting to get out and enjoy being on the water and I like to do some bird and other wildlife photography when I'm out. My main use for a gas outboard of any type would be to allow me to propel my boat upstream for something like two to three hours, then turn around and head back downstream to my put-in, either partially under power from the outboard, or using the trolling motor and/or oars. For a little more information, my KaBoat weighs about 150lb (boat, trolling motor, and battery), excluding myself (170lb) and any other gear I may carry.

So, my main questions are do folks use these motors as the main propulsion for a boat or just to maneuver around in shallow water occasionally? Also, how about noise? I know a regular weedeater of just about any type is loud as all-get-out. I can't imagine hearing that right behind me for two hours. Can the engines be muffled significantly with any kind of aftermarket mufflers? If I was to use one of these how do they do for range/speed? For the lightweight and packability I might even consider one of these as primary propulsion for using my boat to get out and do some camping on some shallow, scenic rivers, provided it would have the oompf to move the boat and camping gear upstream. Am I living in a dream world to even consider this? Are these motor conversions suitable for what I want to do or am I better off trying to find a cheap, used traditional-type gas outboard? The one thing I keep coming back to is that at least a mud motor type of design would be more resistant to damage in the kinds of rivers and lakes I like to go to whereas a traditional outboard would not be. Finally, here's my boat from a couple seasons back - rigged for a photography outing at a local lake.
DSC_0009.JPG
 
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CampbellM

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Jan 13, 2014
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Re: Weedeater conversion as primary propulsion?

So, seriously? Ninety-five views and absolutely no one has any suggestions or answers to a few simple questions?
 

1979checkmate

Petty Officer 1st Class
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Jan 15, 2011
Messages
261
Re: Weedeater conversion as primary propulsion?

i would not use one as main propulsion. Those small engines are not designed to be loaded up for long periods of time. I don't think it would last long at all before meltdown as primary propulsion.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
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47,605
Re: Weedeater conversion as primary propulsion?

your best bet is to look for a good running used outboard. a 10hp (9.8) Mercury 2-stroke short shaft weights in at 65#. you can pick them up running and in well cared for condition for about $400. Then buy an extra prop

However I would probably put on a 4-6hp motor on your rig, especially if you have to portage

Remember, a weedeater motor is a 1.6hp motor that needs RPM's. in most cases, its a cable drive in a nylon sleeve. bolting a prop onto it lugs the motor.
 

bassman284

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Jun 24, 2006
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2,840
Re: Weedeater conversion as primary propulsion?

So, seriously? Ninety-five views and absolutely no one has any suggestions or answers to a few simple questions?

Hey Campbell, how's it going? The weedeater outboard concept comes up here from time to time. As far as I know, no one has been successful in making one work. Weedeater engines are very small and high revving with very little torque. And noisy. By the time you get a prop small enough for the engine to turn at speed, it probably won't move anything big enough to ride. Think egg beater.

Do a search on "weedeater" in this forum and you'll find a number of threads on the subject.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Weedeater conversion as primary propulsion?

I think your trolling motor is a good choice you can raise it up to just under the water for extra clearance.
Get a group 31 deep cycle battery Or 2 6 volt golf cart batteries if you don't mind the complications.
Try to level the boat so it will glide through the water more easily,also will give more clearance to bottom.
I like Deka batteries.
 
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nwcove

Admiral
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May 16, 2011
Messages
6,293
Re: Weedeater conversion as primary propulsion?

jmo...but the weed -eater option is just a basement project that is destined to disappoint. id look into a small, 5 hp or less motor, that can be fitted with a prop guard. keep the troller for backup. even a small ( vintage) omc with the weedless drive, mounted as high as possible is a good option .
 

boobie

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Nov 5, 2009
Messages
20,826
Re: Weedeater conversion as primary propulsion?

Go the small outboard route and forget the weed eater idea. Besides that it will scare the birds. LOL
 

CampbellM

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Jan 13, 2014
Messages
3
Re: Weedeater conversion as primary propulsion?

Thanks for the advice guys. I suspected the cheap weed eater solution would not really work. I just needed to hear it from some other folks with more experience. I'll keep my eyes peeled for a good small outboard on Craigslist and just get a good prop guard for it. One of the things I hadn't done was raise my trolling motor up as high as I could get it. I saw that some folks put a kind of splash guard thing just above the prop to cut down on the splashing when the motor is so close to the surface. I do already have a group 31 AGM battery for my trolling motor. I suppose I could always get a second battery, but they are pretty dang heavy. I live in an apartment so when I take the boat out, I have to cart all that stuff down to my car which can be a bit of a pain when you're lugging that 70lb battery down a flight of stairs. At least I have a dolly to carry the boat/battery/motor to the car. Anyway, thanks again for the input. Sounds like traditional is the way to go.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: Weedeater conversion as primary propulsion?

And don't forget: Weedeaters use about 25-1 oil ratio and use special air cooled oil, not TWC-3
 

steelespike

Supreme Mariner
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Apr 26, 2002
Messages
19,069
Re: Weedeater conversion as primary propulsion?

My bottle of Citgo TCW3 oil lists about every 2 stroke application you can imagine.
 
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