too small a fin ?

[joe_windsurfer]

today was play day
however, water levels are lower than usual
winds were light - so , i rigged an 8.5 loosely on a 160 liter board {am 100 kilos}
for low water levels put on a select 40 cm slalom {usually used with 7-oh}

this was okay for practicing beach n water starts

THEN the wind picked up -- ok, let's see what this setup can do
managed to plane and even go upwind
where it stalled was with tacking #$%&*
even pushing with front foot and leaning sail forward {dangerously} did NOT always help
used to have similar problems with longboard, but could always put center-board down !!

since it was play day - tried moving mast foot back and all the way forward


is there a trick to using a small fin with a big sail ??

in the end i gave up cuz wind really picked up - put a 47 cm antiweed , tightened the sail and put mastfoot @ 3/4 mark and ripped - no problem tacking - did catapult once $%^*