Introduction: 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

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.

Full Spectrum Laser Contest

Participated in the
Full Spectrum Laser Contest