# weedeater mud motor



## sticky28

I've been working on this for a week or so and I'm at a stand still.  
1.Coming up with a way to mount the motor to the boat.
   - used old trolling motor mount, grade 8 bolt, locking nut, square tubing and some conduit clamps.  Plus relocated throttle trigger on to .5" conduit handle mounted on th shaft then bent around the motor towards the operator (like a tiller).  Also I have to take the motor off the shaft and rotate it 180'.  Pretty simple, shaft was slotted so i just cut another  slot on opposite side and slid motor back on.
2. Flex drive shaft was too flimsy(it broke).
   - replace with .25" steel rod w/ nylon bushings.
3.Motor spins clockwise @ 6000rpms or so.
   - trolling motor props want work they are made for counter clockwise rotation.  Also because of the high rpm too big of a prop or a prop with too big of a pitch will choke down the motor.  THIS IS WHERE I'M STUCK.
any ideas would be appreciated. Thanks


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## Medicine Man

*What??*

    I would have no idea how to fix this.. Let us know how this turns out..


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## sticky28

Thats ok laugh it up, by the way I didn't know they let you have computers in the asylum.  Just kidding, I got this idea off another forum and thought i would give it a try.


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## slimbo

I think that is awesome.  My only question is, if you can find a prop, will the little weed eater motor give you enough torque to propel the boat?  I wonder what would happen if you put a lawn mower engine on that shaft.


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## take em

why not use all weedeater parts?i'm thinking maybe using the brush cutting blade(the one that looks like an x)and heat it up to twist the blades in the proper direction to make your own prop.you could set your own pitch and there wouldn't be any attachment issues.only problem that comes to mind is maybe a balance issue.let us know if you pull this one off..........


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## brian chambers

how about a 3 hp prop


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## MudDucker

Looks like 30 days in rehab to me '-)


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## Havana Dude

Me and a buddy had this same idea a few years ago. He wanted something light to put on his pirogue. Funny thing this is where we got stumped too. We never actually put it all together as you have . It seems like we found some sights on the net that you can find different size props, etc. . Sorry but i don't remember what sites we looked on. Try a search on google. Good luck!


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## Medicine Man

I wonder if it will choke down when you put a load on it such as moss,stumps,mud. I ask this because mine in thick grass does. Say what you want if it works perfectly and you pull up to the boat ramp with this people are going to look some thing like this  . If you get it worked out let us know I have a 12ft boat for beaver ponds this would work great on. What about heating a trolling motor prop and reversing the pitch?


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## sticky28

Well  I welded a left handed nut onto a edger blade and started to cut away and shape the blade.  At first with the whole prop the weedeater would not even crank.  As I began to cut down on the diameter of the prop the better the motor ran.  I cut it down to about the size on a trolling motor prop or maybe a little smaller and gave it alittle pitch by bending the trailing edge of the prop out.  When i put it under a load in the water it would only allow the engine to rev to about half rpm, but it sure did cut some lilly pads.  With this setup the boat was not moving very fast at all, about a knot or two.  Next i cut about another inch or so off each end and gave the trailing edge a good twist outward.  When i tried this setup the speed was good maybe 5 knots but the engine still was no where near full rpm.  I guess i'll keep trying different sizes and pitches until i find one that works.  
   For more speed I was thinking about maybe mounting another weedeater beside this one in a twin engine configuration.


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## DCarter001

Good ole American ingenuity.  I hope this thing works out for you.


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## dognducks

look out alatoona


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## quackertackr

there was a post on the refuge forums about this a while back. Great idea for a trolling motor, no battery to worry about. Do a search on it and there will be some info. They were getting there props from Youngs props. They have a website and are fairly reasonable. They did carry reverse pitch props. Great idea.


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## Jason280

I have a little bit of experience with weedeaters and small engines, as I tinker around with them every now and then.  I think the biggest problem you are going to run into, as you may have all ready experienced, is the simple fact these small engines do not develop very much torque.  Displacement on most of these is in the 25-31cc range, which is woefully small for your intentions.   

Most all weedeaters rely on high RPM's to cut grass and weeds, not torque.  Think about it, how many times have you been able to shove a weed eater into a pile of weeds and not have it choke down?  Actually, look at it this way.  When using a weedeater, you have to get it up to speed before you try to cut with it.  If the engine isn't maxed out on its RPM's, it is not going to cut very effectively.  Plus, even at its max RPM's, the motor is easily slowed by the smallest of brush.  And this is in the open air with strings for cutters, which weigh less than an ounce.

Now, consider what you are trying to accomplish.  You want to take the exact same motor, which has a hard time cutting a patch of weeds with two strings on dry land, and stick it in the water with a pitched blade to push around a boat and 200lbs of weight?  

Here's the thing.  *If* you can somehow come up with a prop that works, how fast do you think the motor will push the boat?  Second, as mentioned before, a weedeater must be almost maxed on RPM's before it will work effectively.  How do you plan on accomplishing that under water?  Now, technically you could crank the motor with the prop out of water, and then drop it in.  But, as you have found, you will not be able to maintain max RPM's once that prop is submerged.  I don't think you realize how much torque is truly necessary to turn a prop and move a boat.  

OK, for arguements sake, let's say you solve the prop problem.  That's just the first of a multitude of problems that you have to overcome.  How far do you think you can make it on 12oz of fuel?  Sure, you could rig up a larger tank, but that may be irrelevant if you consider the next problem.  What are you going to do about heat?  All that resistance is going to play wordydirtywordydirtywordydirtywordydirty on the motor, and it is highly probable the motor would overheat in a matter of minutes.  Sure, the engine is air cooled, do you think it is going to be able to keep up with the heat from overworking the engine with a pitched prop?  Then, consider corrosion from water in the shaft.  Most weedeater internals don't get along too well with water, and it would be difficult to seal.  Water has a way of migrating, and it is entirely reasonable to assume it could make it to the engine.   Hey, if it does, I guess you could then consider it a "water cooled" engine!!

Now, for giggles, let's pretend you figure out a way to combat the aforementioned issues.  How fast do you really think this motor will achieve in a jon boat once its filled with waders, decoys, guns, people, and whatever else you need?   Call me skeptical, but I highly doubt it would sustain speeds in excess of a few MPH's in open water.  That's in *calm* open water, mind you.  What do you think will happen if the water is a little rough?  What do you think will happen once you hit the first lilly pad or patch of moss?  Remember, this is the same engine that stuggles to cut a clump of grass with two strings on dry land.  I've seen 25HP outboards choke down on this stuff, can you imagine what would happen to a 25cc engine?   

I think the concept is a good one, but fairly obvious that it would never work.  Now, you could go buy a heavy duty four cycle weedeater, such as a commercial Stihl or Husqvarna, but I don't think they would do much better.  Plus, you are looking at $250-400 for a commercial grade unit (that still wouldn't work).  Now, a lawn mower engine might work, but it would take some engineering.

Nevertheless, I commend your ingenuity!


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## Big Dawg

*Hey man.......*

If it don't work out for ya just weld some wings on it and fly up here to my place and I'll take you out in my boat.   I'm just messin' with ya dude. I hope you can get that to work. I would love to see it. Good luck.


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## Medicine Man

Sticky I hope you do not take this personally. I really like the idea and would have tried it myself. With that being said I have to pull this up every day, it just brings a smile to my face. It makes me think of some of the ideas I have had in the past. Lawn mower engine may work scratch this idea and send us some pictures of the mower engine mounted on the boat.


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## DaveH1

*more threads*

Maybe this idea is workable.  Here's a couple threads including pix of props.  Gear reduction seems to be a key to solving the torque issue...

http://www.boatdesign.net/forums/showthread.php?t=1681&page=5

http://www.boatdesign.net/forums/showthread.php?t=4136

The guys that seem to have taken the idea farthest have apparently dropped off the face of the earth.  

dave


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## Medicine Man

I think the guy's name was Ikka on the second post #8 that said it chokes down every time it goes down in the water. Seems they are running into the same problem.


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## ponyboy

strap a back pack blower to the back of your boat n stick the nozzle in the water n off ya go ........


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## JohnBenoit09

I have attually seen this setup before on GPTV a couple of years ago on an outdoor show they broadcasted and it has always stuck with me. I remember them going through a swamp and it would go really fast!


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## sticky28

*New pics*

This is the latest prop it worked ok but still the rpm is not where i want it to be.  It seems to me the smaller the diameter the more rpms i get out of the motor so i'll cut down this prop alitttle at a time.  I've been sick with a virus so it might be a few more a days before i get a chance to tinker with it.


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## rapid fire

How fast does that push the boat?  What happens if you hit a stump with it?  Will it strip out the gears in the weedeater?


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## craig88

Good Luck with it!! i know it is hard taking all of the jokes but I hope it works so you can prove everyone wrong!


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## roadkill

You might be a redneck if...


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## roadkill

You use a weedeater to make a motor for your boat!


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## roadkill

Jmike said:


> i have to say this is one of the best thread i have ever seen on this forum....that being said, im laughing my *** off right now too! great idea, and i hope it works...im sure there were a lot of folks laughing at the wright brothers before they got the plane off the ground....remember all the ribbing Noah took for the ark....we may all look back and wish we hadnt laughed at you!



I couldn't resist, but I have been know to eat my own words!  I can take it.


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## roadkill

I wonder if you could mount that thing farther forward and put a rudder on the back?  I've got a 12' john boat that needs a motor, maybe I could use your idea to work something up for mine.  Yes, I am a redneck!


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## sticky28

Well I have not done anything w/the motor this weekend but will have some time next week to tinker with it.  The rudder/skeg idea is a definite must but right now I'm trying to figure out how to get more thrust out of the setup.  The best idea I have now is to get a gear head off one of those brush cutter or edger  weedeaters I think they are also like 2:1 gear ratio.  That should get more torque to the prop and let the motor run near full rpm.  If anyone knows about these type gear heads let me know.
  I thank yall for all the feedback both positive and in fun.  I get a kick out of checking the forum to see all the replies.  I am a pretty secure guy that has found good success in my profession and i don't post on here or anywhere else for approval from others.  Keep the ideas and comments coming.

One other thing that i would like to make clear is that, the weedeater mud motor was not my idea.  I saw this on another forum and decided to take the project on.  What i cannot figure out is why some people don't see the relationship between this project and a go devil.  I know this will not be a very powerful motor but for a canoe or gheenoe it just might push it pretty good.


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## Medicine Man

> What i cannot figure out is why some people don't see the relationship between this project and a go devil.



I hate to break it to you, but there is no relationship between a 25cc Weedeater motor and a 6.5hp Briggs & Stratton (which is the smallest Go-Devil offers).  I'm not trying to be mean, as I applaud you for your ingenuity.  But I don't think you will ever make the motor work for your purposes (at least not as well as you think).




> I know this will not be a very powerful motor but for a canoe or gheenoe it just might push it pretty good.



The only way this would ever get the boat going "pretty good" is over the other side of a big waterfall.  




















Just kidding, I'll buy one once you patent it!!


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## Medicine Man

Sticky, 
What ever came of the "mud motor"?


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## sticky28

There is a guy that got this going.  I think it is rickshaw motors, do a google search.  He put a gear box on it, it seems to do ok and would be great for a very small boat like a canoe or some type of layout boat.


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## jdgator

Don't be so quick to knock the idea. I saw a guy build something similiar for a gheenoe using two trolling motor engines. I saw it on Lake Iamonia in Tallahassee, Fl, where you can't have an internal combustion engine.


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## greyghost

I got a Honda 50 motor  if you want to come get it it would be great for what you are trying to do free just come get it and make it work


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## bigunga1

i have often wondered if you could use a 3/4 wheeler engine or even a motorcycle engine with the transmition so you could shift it when ever you wanted....

i dont see why it would not work.... its 4 stroke.... its quiet.... you can gear it down for slow manouvering.... you can gear it up for haul a.....


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## silvertitan

http://refugeforums.com/refuge/showthread.php?t=172396&page=5


post #85


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## silvertitan

http://s82.photobucket.com/albums/j244/Turn4fun/?action=view&current=Mudwackermovie.flv


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## benr149

i have really been thinking about this same thing but just using a go cart motor or lawn mower. I do like how the mud devils come straight off the shaft but what if you hit a stump? Does it break your pin or strip gears or does it just kick up. I like the scavenger back water motors. The are belt driven and it seems if you hit somethin with them it will just slide the belt. But great idea. I hope it works out well for u. prove em wrong!!

link to backwater

http://www.scavengerbackwater.com/


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## southernbound

I think me and this guy would get along real good together but it might get kinda dangerous.


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## huntmstr

I have yuor answer.  First you need to scrap the weedeater motor.  Even if you figure a prop configuration that get the RPMS you need, you will never be able to sustain them because of the lack of torque those motors put out.  Your answer in economical power is a 5hp verticle shaft Sears Roebuck  lawnmower engine.  These are all over the place and can be purchased for about $75.  This engine is ideal for two reasons.  First, it's a verticle shaft so the engine can be mounted on a platform that will swivel and tilt while allowing the  shaft to stick straight off the back of the transome.  Secondly, these motors are made with anti-cyphoning mechanisms that keeps oil and fuel flowing in the right direction, keeping fuel feed consistent and cooling the engine properly.

With the 5hp rating, these mower engines create enough torque from the start to propel a boat at a good clip.  You can simply make a long tail by taking a piece of keyed shaft and coupeling it to the motor via a 4 bolt plate.  Easy to machine one from some flat stock and drilling and tapping for thru-bolt connection.

As for affixing the prop, again a machine shop can spline and thread the end of the shaft for a reasonable amount of money.  to protect the shaft and the prop, you can encase the shaft in a larger diameter pipe and keep the shaft centered with pillow bearings. Then weld a plate skeg with shroud around the prop and you have added protection and spine to your tail. All together, you might have  $400 into it and should push  your boat at about 10-15 mph, loaded. You can even use an external gas tank with a ball valve to afford you greater range as the engine has an internal fuel pump.

I will be attempting to make one this summer, once turkey season is over. I'll keep you posted on how it goes. But I have a feeling it should work well as I have seen one already and my lawnmower mechanic tells me this is the best engine for the job.  Good luck.


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## Gaducker

you will need a horizontal shaft not vertical.


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## huntmstr

Actually, the motor I mentioned is a vertical shaft and will work perfectly. It would not require a horizontal shaft, although that would work as well, obviously.  But the Sears & Roebuck 5hp verticle shaft is the one with the anti-cyphoning features.


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## Gaducker

You gona put a ring and pinon in there to tranmit power at a 90 degree angle????


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## huntmstr

No, the motor can be mounted on a bracket that will swivel and turn, allowing the shaft to come through the floor of the bracket and giving me a place to attach and mount the shroud around the shaft.  YES, you are correct that many can and do use the horizontal shaft motor, but I have found this verticle shaft motor should also work well, and it's more readily available and costs less to obtain.  I'm not trying to get into an argument, it's just a design I've come up with and appears it will work. As I said before, I'll keep you posted once I build it.


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## Gaducker

No, Not trying to argue just trying to understand what you are talking about.  So you are saying you think you can use a vertical motor and tip it up on its side to basicaly use it as a horizontial motor? and you can do this because it has anti siphon feature?  These small motors do noy have a lube system under pressure. they use a slinger system to get oil up to the wrist pin.  The motor you are talking about, has it got a spin on oil filter?   Chris


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## huntmstr

I am not sure.  I was told byt the mechanic I mentioned earlier that this motor would out-perform any other small motor of the same size and purpose for durability, reliability, and ease of maintenance.  I believe, as it was explained to me, that these motors have an internal oil pump that keeps them lubed, no matter what position they are mounted.


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## Gaducker

These motors also have the same carb set up as most others , where the float works off of gravity, the float wont work if its on its side will it?


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## GSUJake

There is a company that makes and sells these motors. I believe it rickshaw. there is also some good threads on the refuge about these builds


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## mudslinger101

Has anyone built one using the plans off of Ebay? If so what did you think? Can you post some pictures of your end product?


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## JWarren

It might be easier to lengthen the shaft on a hand operated trolling motor to accomplish the same thing, it would certainly have more power.


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## bobman

Briggs and Stratton already makes a 5 hp air cooled outboard and it works great. I have on on my 15 foot gheenoe and it will go on a plane with two guys a dog and decoys in it.

the Aircooled engine is nice because it wont suck up mud duck hunting in swampy areas and unlike most mud motors it has a reverse.

I dont duck hunt anymore and have been thinking about selling the rig if anyones interested.


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## Copperswilly

*mud motor plans*

You should be able to find a prop made of plastic used for a small outboard 1 to 3 hp with a mild enough pitch to work with the weedeater. Or a trolling motor prop which you can buy at walmart should work also. If there is to much blade on the prop you can trim it down until the weedeater engine doesnt bog down turing it. Remember a weedeater spins a string head through air water has more resistance


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