I am currently trying to reshape an old stock jp fin that had been damaged. It will only be used occasionally for wave or bump and jump with a 5m combat.

I have worked on it for a while, sanding it back. It does not spin out when jumping or in a straight line but spins out EVERY time when initiating a gybe. No matter how fast or slow.

Why is this happening and what part of the fin is responsible for this?

ps, i know its not my gybing technique

Not too short is it Rich?

Here are the pics of the jp fin,

Originally 30cm now 28cm

It may be something to do with the tip. I have no idea why but I mostly use Select Weedeaters, 24cm. When brand new you can drive them as hard as you like and they never spin out, but as you grind the bottom flat (it gets shallow sometimes where we sail) they start to let go. ???

thanks for the suggestions, I mainly use slalom fins now a days and was wondering what is the point of sweepback on the fin? Less frontal surface area to reduce drag?