Hi,

I would like to know if the board needs a reparation or it is still in good condition to ride. I know something about snowboard board but with the kite board I don't understand if in this case the board loses or not its waterproof ability.

Thanks guys and Happy New Year!

It would be difficult to seal this with no vacuum applied, meaning you'll need a vacuum pump, and epoxy with low viscosity. I might help if u in WA.

That is an easy fix if you have epoxy resin. Mount the rail vertically. Heat your resin up with a heat gun until its super thin. Pour the resin in. Clamp the repair to squeeze the it back to original. Use a plastic bag between clamp and board to stop the clamp sticking to the board. Wipe any excess resin away.
When the epoxy is cured remove the clamp and sand the rail back to shape.

PS You might need to scrape away any excess broken bits inside the dent first to allow the clamp to close the gap properly. A needle or a pin works well.