I ride a bunch of boards - 6'4 semi-fish, 6'0 and 6'2 skinny thrusters, and a 5'4 North (can't remember the model, but it's an older square nose epoxy thingy).
at the moment I've basically got normal sized thruster fins in all of them, except the 6'4 which has one of those small quad back fins in the centre position because I snapped it's original. I find this set up let's the tail release on a cuttie with a lot of power behind it allowing a bit of tail slide, and doesn't seem to lack any drive off the bottom hand turn, but I'd like to loosen it up a bit more for the kiting in the smaller stuff, say up to chest high.
Any gurus know what the optimal set up for this could be?
The bigger problem of smaller fins would probably loosing upwind efficiency rather than loosing drive off the bottom hand turn given we have the kite to help with that anyway.
My set up doesn't have the box like this (not my photo) but the sizing is the same.