Introduction: Sit on Kayak Pedal System
Made from a sit on kayak, a bicycle, weedeater and assorted parts, this water-craft is relatively easy to build, great exercise and fun!
Step 1: Gather Materials
1 sheet of 2" blue insulation foam (4 ft X 8 ft) (or sit-on-top kayak)
1 bicycle (or 'Big Wheel' trike)
1 old 'Weed Eater' or weed whacker of any make
1 wooden or plastic model aircraft propeller (mine's 18 X 12 but somewhere in the range of 10 X 10 to 16 X 16 should do)
1 3/8 drive 90 degree drill chuck
various and sundry wood and metal bits to connect it all
Step 2: Construct Foam Pontoon Boat
Insulation foam is relatively easy to work with and makes a utilitarian pontoon boat. (working on Instructable for my new design)
Alternately follow these directions (Dual-Motor SIP&PUFF Controlled Kayak System or https://www.instructables.com/id/Foamboat-construction/)
Step 3: Construct Propeller Assembly
Disassemble "Weed Eater" to get to the flexible shaft assembly.
Remove the weed whacker head and attach propeller.
Step 4: Mount Bicycle to Pontoon Boat
Use bamboo supports to mount bicycle to pontoon boat
Step 5: Position Propeller Assembly
Position and mount propeller unit to the bicycle/pontoon boat assembly using U-bolts to clamp it in place
Step 6: Pedal Away
Find a pond/lake/river deep enough for your boat/propeller and pedal away!
(Pictures of finished project ASAP!)

Participated in the
Green Living & Technology Challenge
11 Comments
10 years ago on Introduction
whaT IS THE MAKE AND MODEL OF YOUR tricycle thingy?
11 years ago on Introduction
HI Leon , This is just the thing Ihave been looking for . I want to adapt it to my 3 x 7 foot pvc raft. Instead of the prop Iwould like to use a pvc paddle wheel. Does anyone have a simple plan for that? thanks, tropidavo
Reply 10 years ago on Introduction
Maybe you could try something like this: https://www.instructables.com/id/PVC-pipe-blades-and-rotor-for-HAWT-from-scrap/
or this: https://www.instructables.com/id/How-I-built-an-electricity-producing-wind-turbine/step2/Making-the-blades/
Just make the blades shorter. Hope that helps.
Reply 11 years ago on Introduction
I'd try really hard to use the propeller over a paddle wheel. It is way more efficient.
11 years ago on Introduction
This looks great. Could we see the finished project please?
11 years ago on Introduction
is this supposed to pull or push you thru the water ?. I hope you continue and take a lot more pics, Ive been considering something like this for a couple years now
11 years ago on Introduction
Congrat! I was considering a similar design but decided it was too difficult. I've decided to try a paddle wheel system using a trike.
11 years ago on Introduction
Very nice!
I have been struggling with this for a while and then put the project "on hold" (and continued with my other projects).
Can you tell what a weed eater is? I'm very interested. Secondly, I have a similar propellor lying around here and I always assumed that it wouldn't be strong enough. Are you using it without any glass fibre / epoxy coverage?
Reply 11 years ago on Introduction
Weed Eater is a product trade name for a landscaping tool also called a string trimmer. They work by spinning a length of replaceable nylon "string" fast enough to cut grass and weeds, hence the name Weed Eater. They are used to get close to items in a lawn or in areas that are inaccessible to larger mowers like steep hills.
Reply 11 years ago on Introduction
Thanks, I understand now.
11 years ago on Introduction
yes...it's a kayak...NOT a pontoon boat but...the foam boat's not done yet so I just put the pedal assembly on my kayak...as it says you can in the instructable...and there you go! Video soon!