hi, i have a starboard futura technora 155, 8.5 ezzy sail, drake r13 race 520 nr fin, 175 lbs, advanced intermediate sailor, inland lake sailing in michigan 15-25 mph winds. i am spinning out my fin while planing, footstraps are all the way out. this has been happening more & more frequently - do i need a bigger fin? or a better foil shape? any specific fin recommendations would be greatly appreciated.