Mar 27

US Box to Slot Box Fin Conversion – Quick Guide

While Black Projects are available in all major bases there are time when maybe you might need to convert your fin, perhaps you had a US box board and then get a new one with Slot Box? Pedro recently bought a new board  and was in this very position, rather than buy a new fin he decided to convert it. He put together this short guide and he is back on the water with his beloved Freestyle Control.

Objective: We are going to convert a windsurfing US Box fin into a Slot Box fin (picture A).

Tools: Hacksaw, screwdriver, fine sand paper, drill or grinder
Time: 30 minutes

First we need make three modifications to the US box fin (Picture B):

  • Knock out the pin
  • Cut off the front tab
  • Cut off the bottom tab

I would recommend to use a piece of fine sand paper to smooth the rough edges.

That only took 20 minutes and we are almost done. Insert the modified fin into the slot box and tighten both screws so that they leave a mark on the fin (Picture C); make sure the fin is sitting nicely before tightening the screws.

Take the fin out and using a drill or a grinder make a groove or a shallow hole for the box screws to secure the fin. Be careful not to remove too much material, the penetration is mostly superficial. Go for a spin and enjoy!

Thanks to Pedro for producing this guide, if you live the the San Francisco Bay Area then you’ll see him ripping it on!

More to follow…