The electric hydrofoil surfboard is by far my biggest 3D printing project. I got the idea off a
forum I found and decided to make an electric hydrofoil surfboard for WISE. WISE is an English class for seniors at my high school where you have a regular English class for the first half of the year, and a large personal project for the second half of the year. One of the engineers from my robotics team agreed to be my mentor for the project.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeaE3b-7yQX3Y78GISROpXaCyGiuc7GcCyois5KGewvmNouteLuUCmPMZQzCBRRgcfjUy0OVaB3-xNF0NTlnjptEu1sHssSzELi6r4Ev4eBCl-tIzkBLEwuGT4QCorkBaLTYuvik6_Nkg/w478-h417/foiling2.jpg) |
Testing the finished hydrofoil
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I used a modified version of one of the builds on the electric hydrofoil forum when doing the project. This made the project a lot easier since someone had already tested most of the components such as the propellors, motor, motor controller, and gearbox. I learned a lot about o-rings and proper sealing procedures even just from building and modifying the designs other people worked on.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhN6zjLUK2eFtLYlgl2jPlu9MrHZQ5uWbWbjbiAsCW-KOeucIkAfq33VsH3IhxR760ku4VfL_B27yZcH971KK-f4rYop1QgTYiWJ0nJPQrylc9KN3hMNXF8kY6J9u5iy4ST7tKrsP1U0Wk/w358-h269/IMG_20180307_185639.jpg) |
This tiny motor has a peak power of 10hp
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![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5mBTwuz0COyXUgMK2V3CEmzJsNjFl4z0ZOlU8fV9Jsxg9KPmRFka4-4vRh1Gc8i8uQOfxycV6FDpRDSBQNZJOtURmjpStHrZCMcbBZdKeG57r_0-AFJMshKI2qEccC4U5bVBHszfcyO8/w357-h268/IMG_20180406_001725.jpg) |
Test fitting the motor assembly
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To make the hydrofoil wings I copied an airfoil shape from a
database and used guided lofts and extrusions in Autodesk Inventor to get the shape I wanted. I made the wings swept back for additional stability and added mounts to integrate it to the rest of the hydrofoil. I also added aluminum beams to the center for extra support and used the Autodesk Inventor FEA to analyze the stresses in the beams.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLfn2z88Iwh2QHZsl2YOlU6R3sDhpL2p29og7RftLEFuVkADih4UH1R2mAWhgHWrMojy6XinWPGkA9ARh9JwRO2oHFAMNggdQBt6-BFgtyNx2O1iLMg1KoixilN7qwQYvls8gPXmr5WFs/w440-h227/hydro.JPG) |
Autodesk Inventor CAD model
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![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2bihaDVyULZFc7P5kknIzpv2LEa1RUV2cB3qGwxryhXo8nS2JDxXrLugO6Jv6offX1JxQA-fEif0xbSYEq7k9YCn7qzqxOrBNHS4t5F0QN0d-TeAfOWy8SerZ1cX8Z5X9A47xr7K9wZw/w477-h247/stressanalysishydro.JPG) |
Stress analysis of the larger support beam
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Throughout the project, there were a few setbacks. The first was the motor housing getting mangled in the lathe when I tried to take off a pass that was too large. Luckily I was able to get a new one for free from a guy I knew at a local shop.
Another problem I ran into was the propellor duct snapped after the first day of testing. I reprinted it with more perimeters and infill and was out testing next week.
After a few days of testing the motor controller caught on fire. This was caused by insufficient cooling and I got lucky it didn't burn the batteries or any other electronics. In later versions, I added a pump and water cooling and didn't run into any more problems.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaC1B4yl6k3HERyRyaqMdS0kIwezG6z6vnWBdCbh9cwV4VV3Ezb8w6GlMUKkzcTj5CWtWKnFy_hTHC156x42r22gnbwHl8E3PQMaEXNgTLOqkONjZmVAYhvJQfTOLQxb-PPhFTT6khTS0/w470-h353/IMG_20180617_164553.jpg) |
Burnt motor controller
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgU17pJnxuBZU5AYnl7axBQrcmn3dvTcB6LFAoRe59Ijzu-yaM5y_hrSguVlEqpViAqU_a4muePRO4-xec4kOQZVvK26u3zWhlVBCuQgxmy5yxuIzjO8tdC9GXStl5XWmftFblZXTKCrgo/w397-h370/pumptesting.PNG) | Testing the cooling pump
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The last major problem I had was the original wings weren't large enough to lift the surfboard with me on it out of the water. I designed new hydrofoil wings with a more efficient airfoil and a much larger surface area.
Left: new wings Right: new wing size comparison
In the end I never quite got the hydrofoil working. I was able to get out of the water but a combination of me being inexperienced and me designing and 3D printing my own hydrofoil instead of buying an off the shelf solution made for a very unstable surfboard. I had a lot of test runs similar to the one above where the hydrofoil went up and then I fell back down.
Overall, I'd say the project was still successful because of how much I learned. Before this project, I knew absolutely nothing about o-ring seals, fiberglass layups, airfoil profiles, brushless motor control, and how to properly spec out batteries and electronics.