A few users have been interested in the 3d printed hydrofoil I made so I’m going to go through and explain how I did it and how it turned out. The newest version of the foil worked successfully and I’m still doing further testing to make the design better. The total cost of the foil is $32.
Designing the foil, I used the EPPLER 817 profile from airfoiltools. I designed it in Autodesk Inventor which is free for students.
My 3d printer has a 10" circular bed with a height of 12". This is larger than most printers and may be an issue for some people. I printed all of the foils in PLA at 0.25mm with 3 perimeters and 65% infill.
For the inside of the foils I bought some aluminium off amazon, which is used to keep the foils from bending and also makes an easy connection to the fuselage. I machined it into two pieces, one was 12" x 0.5" x 0.5" the other was 12" x 0.5" x 0.375". I had to sand these to make them properly press fit into the 3d printed foils.
I made the fuselage out of aluminum 1x1 extrusion and added 3d printed end caps to it, which I press fit in.
At first I printed the foils too small and I couldn’t get enough lift to get out of the water. I didn’t end up putting fiberglass on the new foil however I added some images of how I did it for the smaller one. The basic technique is to have a tiny overlap in the front and a larger overlap in the back and do one side at a time. Afterwards, use a lot of sanding to get everything smooth. I spray painted the foils red as well.
In the images, the red foils are the old kind with fiberglass and the white foil is the new version.
Washers can be added near the fuselage to mess with the angle of attack of the foil.
This image is just for a size comparison between the new white foil and the old red one. The new foil has an area of ~190in^2 total.
This is the best image I could find for the fiberglassing of the foils. I had to add some of the glue back where the fiberglass began to split.
Disclaimer: I’m still in high school and I barely know what I’m doing. The foils I designed aren’t necessarily optimized or stable they’re just a fun project I’m doing.