RE: Fin or mast track position
So, you are "spinning out" the fin.
What size sail (s) vs what size fin (s).
What type (i.e. brand and model) sails and fins are you using?
How much wind?
How big is the chop?
Are you "spinning out" on a beam reach, or only when you try to
What is your weight?
I doubt that the type of harness you are using makes a whole lot of difference here, but your line length and positioning might have some effect.
Hope this helps,