Electrify Any SUP or Kayak With a Universal Fin Mount

I've been working on a DIY electric kayak for a while but I recently upgraded my kayak which unlocked a goal that I have been wanting to tackle for a while. A more universal fin. While this Instructable is short and sweet, it's the start of something much larger. A platform to build on for not only kayaks, but also stand up paddle (SUP) boards.

In this Instructable, I'll share my new fin design (anyone can download the stl or Fusion360 files on my github for free), what I learned from testing and all my hair-brained ideas for the future.

Check out my latest YouTube video showing the new fin and kayak in action! Not to mention, getting followed by a seal!

Huge thanks to PCBWay for sponsoring the new fin prints and supporting makers like me! Get $5 dollars off your first order!

Lower to medium end SUP and inflatable kayaks all use a universal fin box mounting style called "Slide In". Think Costco SUP. A large track for the fin to slide into with a clip that locks it into place. I have been wanting to move the e-kayak to that fin mount style since the beginning and make it more accessible. But my original kayak was an old hammy down with a one off fin mount style.

This past summer, I bought a new kayak and was ready to make the upgrade!

I took my old fin design and re-did the bottom mounting half. I started meticulously measuring the kayak fin box dimensions (a measure twice, cut once type of thing). Turns out the base of the fin actually has a slight outward tapper like a V shape. I opened up Fusion360 and started extruding. Once it was ready, I shipped off the files to PCBWay for printing!

PCBWay makes it incredibly easy to order 3D prints. I just uploaded my .stl files and chose from dozens of customizable options like print material, color, finishes and more. Using the material descriptions, I chose black Resin for it's water resistant qualities. After submitting my order, PCBWay's own engineers even reviewed my designs for any issues (More on this later). All in, the fin cost about ~$40 and the shipping cost ~$40. Everything took about a week and a half to print and ship here. The print quality is amazing. The fin looks like it was cast from a mold.

Get $5 dollars off your first order!

The motor fit perfectly into the new fin first try. I decided to push my luck and skip the lake. Straight to the salty ocean for a true stress test.

Overall, the test was a success. The fin didn't show any signs of water intrusion or deterioration, even after multiple salt baths. I even got some sweet footage of a seal following us in the kayak.

The only issue I've noticed is how thin I made the point of the fin. I had to be careful about the fin dragging on the bottom and have noticed some small chipping over a few uses. Remember how I said PCBWay will actually review your designs before printing to ensure there are no issues? They caught this right away and warned me that the fin point would be very thin. I told them to print it regardless. Probably should have listened to the professionals. Either way, this was a successful test in my book!

I've got a few lessons learned and a few ideas for the future!

I plan on getting rid of the tapering design that brings the fin to a point and just make it all one thickness with Fillet edges. I think this will be plenty hydrodynamic and way stronger. I won't have to worry about dragging the tip on the bottom as much.

I also want to de-couple the base fin and the motor mount into two separate pieces so that other motor mounting styles can easily be "clipped" onto the fin base. I envision a future where people can keep adding support for any motor into the project.

This is the static version but I will also be working on a fin version with an integrated servo for direction control.

Lastly, I want to integrate a GoPro mount into the fin with a light to catch more marine life in action!

Thanks for reading! Check out my full e-kayak playlist to see the full project and subscribe to keep up on my progress!