Here's what guy Cribb suggests- he advises against women wearing waist harness's.
The hour-glass shape of a woman has many benefits
and attractions, but it is not a good shape
for wearing a waist harness. If you put the harness
on the widest point, naturally it is going to slide
up into the narrower area, before finally becoming
jammed under your ribs. It's not comfortable
and it is very poor for your windsurfing as once
the harness has risen the pull of the lines is more
horizontal than vertical, and as such no longer
naturally suspends your weight from them, but
puts all your weight on your feet rather than the
mast foot. No wonder it's hard to plane.
As an intermediate to advanced windsurfer it
is paramount that you maintain good mast foot
pressure/downforce on the board, for control.
There are many girls who have overcome these
'high hook' problems with extensive time on the
water, a straighter body shape and by adjusting
their boom heights higher than normal.
However girls with the wide hips should definitely
try seat harnesses. I have changed so many
guests windsurfing for the better, and one of the
most instant results is getting girls to try seat harnesses.
It turns on the power, acceleration, top
speeds and jumps instantly. Whether they stick
with the seat harness or return to a waist harness
is irrelevant- the fact that they have felt the benefit
of using the lower hook is enough, they all now
understand the importance of pushing their harness
down if it slides up.
Here's the full article but I don't know if you can make it large enough to read easily? Thanks Ruth for the info.
www.guycribb.com/userfiles/documents/Tuning-%20long%20lines.pdf