Hydrofoil Bicycle




Have you ever seen a hydrofoil bicycle? Most people have not, but they are now starting to become popular with colleges and professors. Most colleges make them because they are created from complex blueprints and they are trying to perfect the hydrofoil designs. There is a video on YouTube showing a man on a bicycle cycling on water. He wasn’t pedaling very fast yet he was going at a pretty good speed. A bicycle is operated by pedaling because of a chain/pulley which is attached to the wheels. Pedaling then causes the bike to move. A hydrofoil has these wings (hydrofoils) that lift the whole product on top of the water so that it skims the water, reducing friction. There are no wheels but the chains and a propeller move the bike. This product would be good to make because many kids are not allowed to ride their bikes around their neighborhood or they have a lake but they can’t go out on it because it takes a lot of time and

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Step 1: Items Needed

All should be old recycled/donated material to avoid expenses
1.1 Kayak

2.90 degree gear

3.Several Propellers

4.Bicycle for drive train (frame, pedals, chain, and sprockets)

5.Several long pieces of squared steel

6.Tape Measure


8.1 10 ft PVC pipe

9.4 PVC caps

10.Cement Glue

11.Several Bungee Cords


13.At least 15 2 L soda bottles                                                         

Step 2: Access to the Following


2.Different saws



Step 3: Flotation Base Unit

My Dad donated a 27-year old kayak.
• Lightweight (made of fiberglass)
• Has an under the stern rudder
• It is “tippy” (racing boat).
• Needs patching to prevent leaks

Step 4: Collecting Components

Collecting components for possible use for the “power source” and the “propulsion” source.
I searched for possible recycled materials from boat shops, bicycle stores, Craig’s list, etc.
• USC machine shop donated a 90 degree gear, and a couple of propellers.
• Purchased one model  airplane propeller from Landing Products in California. ( $12.95 + shipping)
• Bicycle for drive train (frame, pedals, chain and sprockets)
Collected from trash pick-up pile, Florence, AL.

Step 5: Collecting Components (Con't)

Collecting components for possible use in the “power source” and the “propulsion” source. (Continued)

• Cato Power Equipment, Columbia SC donated a used weed eater flexible shaft (a coiled wire)
• USC Machine shop donated machining service to manufacture a bearing connector to the propeller and flexible shaft.

Step 6: Measuring

Measuring “1/2 circumference at different distances along the length of the kayak to estimate the average cross sectional area, that was used to estimate the partially submerged volume of the kayak. Measuring the length of the string used to estimate the circumference at distances various along the length.

Step 7: Preparing the Frame

Measuring the lengths of scrap metal donated by my Uncle Ronnie.
The square metal (steel) rods are used to make the frame for the bicycle and pontoon flotation.
Aluminum would have been better (light but strong) but Uncle Ronnie had scrap steel, so economics took priority.)Sanding the cut ends of the metal rods to prepare them to be welded together. (My Grandfather is helping hold the other end of the rod).

Step 8:

Sanding the cut ends. Clamping the ends of the metal rods together in preparation for welding.
Welding is a technique of joining metal pieces together by melting the ends at very high temperatures. The pieces bond and cool to a single piece. It is a dangerous process, so I observed while wearing a welding helmet that had a dark face shield to protect the eyes.

Step 9: Setting the Frame

Shifting the welded frame base to the kayak. The old bicycle frame was welded to the metal frame base.
The bicycle is 40-year old Sears bike. It was donated by my Grandfather.

Step 10: Testing the Propellers

Testing propellers to see which one provided the greatest pushing force.
Approach: each propeller was attached to a long steel rod that was locked onto a variable speed drill. As the drill rotated at slower speeds, the propeller rotated in the water.  The different propeller designs produced different “push” forces at different rotation speeds.Once the propellers were tested, the most efficient one was chosen and prepared to be bolted to the metal frame.
Pictured is a donated 4-bladed model airplane propeller. I finally decided on a 2-bladed 16-inch model airplane propeller.  It seemed to push more at the low rpm.

Step 11: Mounted

The propeller mounted.

Step 12: January - February 2014

Attached the rear sprocket of the Sears bike to the front of the frame. (Welding service contributed by USC college of engineering Machine Shop)

1. Attached the 90 degree gear (removed from a damaged grinder tool donated by Uncle Ronnie).
2. Replaced the chain and seat with donated parts from Harrell’s Bike Shop. 
3. Checked the rotation speed- of the propeller by rotating the pedals by hand. The old Sears bike pedal ring had 36 teeth and the rear hub ring had 18 teeth – about a  2:1 gear ratio.
4. Modification made: Harrell’s Bike Shop donated a set of rings. A 48 tooth ring was attached to the old 36 tooth ring. So the gear ratio for the bike was increased to 2.5:1. (Welding service provided by USC CEC Machine Shop).                                                                       5. Patched the bottom and sides of the kayak with duct tape to get it ready to test in the lake.

Step 13: Pontoon Flotation

Prepared the pontoon flotation - Used 6-inch PCV pipe donated by Gateway Supply.
• Cut a 10 ft. length into two 5 ft. lengths. Placed empty two liter soft drink bottles inside the pipe for “emergency” flotation in-case a pipe started leaking.
• Glued PVC end caps to the pipes.
• Place empty 2 L bottles inside before sealing
• Strapped the pipe pontoons to the metal frame as “out riggers”.
(Used 4 cords at a total cost of $6)

Step 14: Attaching Flotation

. Strapped the kayak to the metal frame with bungee cords.
(Used 3 cords for a total cost of approximately $6).
•  Strapped the pipe pontoons to the metal frame as “out riggers”.
(Used 4 cords at a total cost of $6)
• Attached the pontoons with short bungee cords  (4 each)

Step 15: The Rudder

Attached the rudder wires to the bolt on the front fork of the bicycle. Lubricated the chain sprockets and gears with WD-40.

Step 16:

Date:  Saturday, March 22, 2014; Time: 4:00 pm
My mom and dad helped me get the water bike onto the lake for the initial testing.
• Performed a flotation test before getting on the water bike.
• Gradually, started pedaling the bike to allow the craft to build up speed.
• Unfortunately after going about 50 yards the 90 degree gear broke loose and would not turn the propeller. 
• Discovered that water was slowly leaking in through the bottom of the kayak where the rudder was attached and through a small crack at the very tip end of the kayak.

Step 17:

24. March 25, 2014. Broke the gear box down and discovered that the rotational direction caused the attachment nut for the beveled gear. To “unscrew”.

25. Path forward based on the first test run results:
• Use a propeller that will allow rotation in the counterclockwise direction to “push” the waterbike and prevent the attachment nut for the bevel gear from unscrewing.
• (Purchased a model airplane propeller from Landing Products in California. (counter-rotation) ( $19.95 + shipping). This propeller is a 16:14 pitch (16 inch diameter with one rotation pushes the water 14 inches).
• Seal around the rudder with silicone
• Duct tape the end of the kayak
• Perform a second test run

25. Date: Time:
Performed a second test run Pine Tree Lake, Columbia, SC.
(1) Started by gently pedaling
(2) Increased the pedaling rate gradually toward the center of the lake until reaching about 30-40 rpm (for the pedals) which gave about 90-120 rpm for the propeller.
(3) My father measured the time it took for me to pedal the bike along a known distance between two points. I estimated the speed as ΔL/T.
(4) I repeated this test two more times and calculated the average speed.

26. Conclusions based on the construction and testing of this water bike:
` (1). Need to better repair leaks in the kayak to make it more waterproof.
(2). Fine tune the rudder to allow more efficient turns.
(3). Use aluminum instead of steel to make transportation easier.
(4). Redesign for faster speed.

Update: Phase 2: Second Experimental Run

1. The water bike reached speeds of about 3-5 miles/hour

2. The water bike can not "fly/hydrofoil" with hydrofoils at these low speeds. Based on background research, the speed will probably need to be greater than 10 miles/hour to sustain "flight."

3. The path forward for Phase 2 will be to repair all leaks in the kayak, tighten up the 90 degree gear to prevent "slipping", test the water bike to see if the speeds of about 10 miles/hour or more can be reached, then construct two hydrofoils out of 1 x 4 boards to attach to the underside of the steel frame.

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    29 Discussions


    1 year ago

    That's a pretty cool water craft. Looks like lots of fun, although I wouldn't call it a hydrofoil. A hydrofoil goes fast enough that it rises out of the water so that the hull is no longer in contact with the water's surface. The craft then proceed on risers that are equipped with foils that plane off of the water as long as speed it maintained.


    2 years ago

    i want to make yhis because a could pass canoes and " say nice day for a bike, Huh"


    3 years ago

    thats crazy I alwanted nake a bike on water but mayb wit sum kinda electric motor wit sum battrries and a panel


    4 years ago on Step 17

    This is sweet, Any chance you might have a video that would show the mechanisms of how your peddling turns into the propulsion system. Cant quite make it out. Very neat ride! Lots of Effort!!


    5 years ago on Step 17

    Great work! Congratulations!

    Is there an engineering school near you which would donate time to design and construct an optimal propeller for your hydrofoil?


    5 years ago on Step 17

    Nicely done!!!

    Great job for an initial mock-up. Please continue to post any information on addition tweaks and modifications, so that we may follow your work...


    5 years ago on Step 12

    very nice & informative!


    5 years ago on Introduction

    Okay so I updated my project. At the end it explains the no "wings" aspect.


    5 years ago on Introduction

    pdesai2 is correct. It is a pretty cool design for a bicycle powered kayak, but there is no "hydrofoil" aspect to this design. A hydrofoil rides upon "wings", this does not possess them.


    5 years ago on Introduction

    Very nice instructable but it is mis-labelled. There is no hydrofoil in this project. As many have pointed out below, the outrigger design in the instructable is more accurately described as a catamaran/trimaran. It might be nice if you changed the Instructable title and descriptions to reflect this. It is better for people searching the site if things are accurately described.

    Other than that, it is a really nice instructable - keep it up.


    5 years ago on Step 17

    Excellent educational project. Nice work...and very good work documenting every step and the results of all the work.


    5 years ago on Step 17

    Great job. Very detail instructions and nice photos. Enjoyed reading your article very much.


    5 years ago on Introduction

    Amazing Instructable , Amazing Team Work!

    Keep up the Good Work!


    5 years ago on Introduction

    The kayak can be eliminated. Buckminster Fuller patented the Dymaxion Rowing Shell, or rowing needle, in 1968, which was essentially two lengths of plastic pipe connected fore and aft of a seating platform.



    5 years ago on Introduction

    This is not a hydrofoil. Hydrofoils are underwater "wings" that lift to boat right out of the water. This is a canoe with outriggers or a trimaran if you like.


    5 years ago on Step 17

    I'm looking for the hydrofoil parts and I don't see them. Can you show them to us?


    5 years ago on Introduction

    really nice job on your project so far. There was a product made a few years ago called the wavebike that was similar to what you were doing. Unfortunately the YouTube videos have been taken down since they used music that was under copyright. There are still some photos and drawings if you Google wavebike.

    You might also try and google the flying fish hydrofoil. This was the first pedal powered hydrofoil to work. Here is a link to a YouTube video of their very first test before they put the floats on it:



    5 years ago

    awesome project! definitely look into a marine propeller, they are much more efficient for water. you would probably be surprised by how much more speed you could get with a proper marine propeller

    1 reply

    Reply 5 years ago on Introduction

    Actually several of the successful pedal powered hydrofoils have used model airplane propellers. The low speed of the pedaling combined with with the higher density of the water .