isonic 117 wide
"""Downhaul: I guess downhaul has to do with the wind power more than with the board feeling"""
Really.. the downhaul affect the pressure on the board.
less downhaul, more pressure on the board
more downhaul. less pressure on the board.
from the experience that i discovered from testing this board is that if you have to much downhaul the board will go too high in the water and as a result put more pressure on your backleg.
Reverse if you put less downhaul your board can feel a bit sticky.
This is within 2 cm on the downhaul on my 9.5 sail.
I recently used my 9.5 sail and my select 47 s10
i had pulled the sail according to specs: 522cm downhaul.
Went out and the had a lot of pressure on the backfoot and had a hard time to go upwind.
I changed the setting and discovered that my harness lines were a bit off and then i moved the mastbase forward and dropped the boom down .
this gave me a pretty ok setup but not good.
Day 2 i used the same setup except doing the rigging visually.
i checked the loose leach on the upper part of the sail and used 520.5 cm downhaul since 522 gave a very loose sail.
The end result was a centered mastbase position and normal upwind ability and a more relaxed stance.
So my experience with my sails and this board is that too much downhaul gives me the problems you describe big time.
This is for gunsails mega xs and north warp f2011 and select s10 47 cm and black fins project type r 45 cm
This is racing equipment.. trim and trim and trim...otherwise buy a freerideboard.
good luck !!