Est: Oct 2009

Charles Weidner <>

Linux used exclusively for all projects!

Custom Paddlewheel

paddle wheel

I designed and built the boat and motor you see on these pages. I also built the trailer, but the design came from a book "How to Build Boat Trailers" expanded second edition by Glen L. Witt. You can order it from his website: It was well worth the money! You see, I don't mind designing a boat that only goes 10 mph, but to pull it to the nearest body of water at 70 mph requires a well designed trailer!

I can easily make design changes to the boat if I get it wrong. The boat is a test bed for learning about building boats and has served well for 2 years with more expected.

6.5 hp goes 6.5 mph with a paddle wheel - as fast as the outboards for this boat. Motor features - neutral and forward speeds - height adjust while running - tiller turning.

boat CAD drawing

Q-cad works well for laying out parts and assemblies.

paddle wheel1 paddle wheel1-2

Below is a picture of paddle wheel #1. It was faster than the trolling motor at 4 mph plus! With a riding lawn mower transmission it had 4 forward speeds, neutral, and reverse.

Reverse was only good for filling the back of the boat full of water and drowning the Captain!

The four forward speeds did allow for determining the best wheel speed for thrust. Lessons learned from this motor were: the 20 lb transmission was not worth its weight, and depth adjustment on the fly is a good thing!

Paddle Wheel #1 was a proof of concept and was slapped together without painting.

paddle wheel3

It worked well enough to warrant building #2, yellow paddlewheel!

The "yellow paddlewheel"

Below is paddle wheel #2 known as "yellow paddlewheel" for obvious reasons.


Works very well. It is comparable to an outboard of the same size. Weighs slightly more I have a 50 lb 1974 Sears Ted Williams 7.5hp that will push this boat 5.5 mph. and a 55 lb 1964 Evinrude 9.5 hp that goes 8 mph. The yellow paddlewheel will push it 6.5 mph full throttle and 3.4 mph at idle. The 30 lb thrust trolling goes 3 mph on a calm day. paddle wheel #1 was 4 hp and weighed over 100 lbs speed was probably between 4 and 5 mph. All speeds were by gps except paddlewheel #1 which was a guess. I have not weighed the complete paddlewheel motor. The gas engine is 38 lbs. the wooden wheel was 18 lbs. There are three 10 foot sticks of 1" square tubing that weighs 5 lbs per stick. There is probably 10 lbs of sprocket and pulleys and another 10 lbs of wooden wheel spray cover. Total about 91 lbs.

Advantages of a Paddle Wheel

  1. cost - new 10 hp outboard $2000-$2500 paddlewheel - engine $130, bearings $40, steel $50, plywood $30, epoxy $30, misc $40 total $290 I have not verified this but I believe this little overhead valve engine and paddle wheel uses less fuel to get me across the lake than the outboards. Also the gas costs less because I didn't have to add oil to it.
  2. maintenance - if you can fix a lawn mower you can fix this thing. All bearings are above the water line. They get sprayed, but are not subjected to the pressure of submersion. There are no special tools or tricky set ups needed.
  3. pollution - no oil mix and exhaust not routed to the water.
  4. noise - this wheel is quieter than either of my 2 outboards. Possibly because it runs at much lower rpm. The sound it does make is pleasant, kind of like a waterfall.
  5. weeds - nothing beats a paddle wheel through the weeds, I have tried this several times. So far the weeds just push down and under the wheel, they do not wind up around it.

Disadvantages of a Paddle Wheel

  1. speed - although the speed is comparable for my boat (it is a displacment hull) paddle wheels do not develop much speed (average 8mph, 15mph would be really fast). Paddle wheels are capable of great low speed thrust. The problem is as the wheel speeds up it develops a cavitation problem. It will throw the water far behind the boat and there is no time for the water to fill the hole dug in the lake water before the next paddle (bucket) arrives. No water, no thrust.
  2. size - this thing does stick out the back a ways. It seems to require more attention at docking time to prevent bumping the paddle wheel into something like the dock or another boat. The extra size is not a problem on the lake.
  3. stares - The paddle wheel does attract attention from people. If you like attention this might be for you.
pic gas motor pic gas motor
Pictured above is a 6.5 horsepower engine purchased new at Harbor Freight
I hesitate to mention the brand, as it has changed since I bought it.
I think they are now called Greyhound. I have seen the same motor at
a farm supply store on sprayers and water pumps. The engine is tagged with a manufacturer's label in case anyone is wondering who makes this engine! Self - explanatory is all I can say!

This is part of a car jack from a 1984 Mercury Marquis II. The threaded rod, block and bearing allow the motor to be raised or lowered on the fly. Paddle wheels work better at the correct water depth. Best way to find that is to just move it up and down till you find it.

Engine Temperature Guage Sending Unit

pic temp guage pic tempguage

Boat motors do not get a chance to rest, the water is constantly providing resistance, with the possible exception of slowing down. This old temp guage had just been begging to be used for years. The engine needs to be warmer than 130 degrees to even begin to move the needle on the guage. At idle the boat moves at 3 mph and needle is resting on the peg (cold) and you can put your hand on the crankcase near the guage. At full throttle the temp gets to about 160 and the crankcase get a little to warm to touch. In contrast my 4 hp pressure washer gets so hot that the crankcase instantly boils any water that splatters on it. And you do not want to get anywhere close to it! I am confident that as long as I keep the oil at the proper level it will not burn up

Engine Temperature Guage

pic temp guage pic tempguage

Getting ready for a ride! No girls allowed!

pic gas motor

Here we go!

pic gas motor

Now its the girls turn

A camera captures spray patterns that you don't see with the eye!
pic gas motor pic gas motor

NEW - plans for building paddle wheel out of fiberglass epoxy resin and wood!.

The plans will include blueprints pictures and instructions for everything you need to to sucessfully build you own wheel. The Wheel will handle 3 to 12 horsepower and propell a small boat to about 8 mph. This will be for the wheel and the drive sprocket mounted on the wheel. With some ideas about how to mount and power it on a boat!