Covering those tracks

[bragnouff]

This is mostly for owners of "convertible" foil/surf boards.
My previous boards had inserts for foil attachments, or traversing holes which were easy to just ignore or easy to plug with candle wax.
Now my travel board has 2 US boxes for foil mount, which allows some good foil adjustment, but on the other hand when used in surf mode, those tracks definitely add some parasitic drag, and rob you of a couple of knots in the lower windrange. I tend to ride smaller kites than most, and get my adequate level of power by riding fast and keeping the speed up, so unnecessary drag is a hassle. Not a problem if riding lit as a bug.

I've been using some aluminium tape to cover the tracks, and it worked great initially, it's light, it's thin and it's shiny, but after a few hours, it seems to be peeling off or crumpling on the sides which can easily add even more drag than having no cover at all. Maybe a better prep of the surface with isopropyl alcohol would help, something to try next time. Otherwise I've been thinking of light 3D printed inserts to fill the tracks, but I expect the cover to be not 100% perfect either.

Anyone with experience on that domain?

[GregK]

Try a pair of dense EVA foam strips slightly thicker than the US fin box width and deep enough to fill the box.

Back in the 1990's I had a custom twin-fin sailboard with US boxes for the twin fins as well as a Tuttle fin box to run it single-fin. When riding single-fin, I plugged the US boxes with EVA foam strips, and that worked well.

[ieism]

I use Oraguard 270 Stone Guard Film. It's invisible and stuck really good to smooth surfaces.

This is the same stuff as a "clearbra" for cars. I'm sure you can go to a company that wraps cars and get some offcuts for free.

[Trent hink]

These days I don’t bother, but in my windsurfing days we would cover the exposed portions of the fin boxes with cellophane tape.

[Herman]

^^+1 Also used what I called brown parcel tape. Useful over a ding waiting for repair. Some windsurf shops used to sell Eva foam filler strips for US boxes.