Setting up
the headsail
1
SET THE HEADSAIL HALYARD
Raise the headsail and set the
halyard tension to get rid of any
horizontal creases, but not so much
that you introduce vertical creases.
This will ensure it is as efficient
as possible. A headsail that has
vertical creases means that
the halyard is too tight.THE PHYSICS
When we are sailing to windward,
the sail acts like the wing of
an aircraft. Air passing over it
produces a low pressure area on
the lee side and a high pressure
area on the windward side, which
creates lift.
This lift from the sails
is countered by the lateral
resistance of the keel. Without
a keel, a sailing boat would
simply go sideways. But, as
long as the total force – the
centre of effort on the sails- is countered by the lateral
resistance of the keel – what’s
known as hydrodynamic force –
and these forces are in balance
and acting in line with each
other, the boat will sail forwards.
On the physics front, we also
need to consider wind shear.
The friction of the water on the
gradient wind causes
it to back and slow
down the closer it
comes to the surface
of the water and so
there is a difference in
wind speed and wind
angle between the top
of the mast and the
deck. The higher up,
the greater the wind
speed and the more
the wind angle moves
aft. The lower down,
the lower the wind
speed and the more
the angle moves
forward (backed).
So we need to be
able to adjust the twist in our
sails to take advantage of this.
The headsail acts as the
forward driving force, and the
main, affected by the sideways
force of the wind, is more like
a rudder, turning the bow to
windward as it powers up. So we
need to know what sail shape we
should be making to get the most
out of the wind we are given. In
light airs, we want a fuller sail
shape – a more powerful shape- and in heavy airs a flatter, less
powerful shape. There are several
elements that we can adjust for
the headsail; twist, depth and
draught position. And for the
main; twist, depth, draught
position and helm balance.
All of these can be adjusted easily
with the exception of draught
position, which requires us to
alter the halyard tension. And as
I don’t think it’s realistic
for us to be running
up and down tweaking
halyards for every
point of sail and wind
strength, I’m leaving
draught position
alone. The controls
for adjusting the
set of the headsail are:
Q Forestay tension
Q Halyard tension
Q Position of
the sheet lead
Q Car on the
genoa track
Q Sheet tension2
SET THE GENOA CAR
Follow the sheet from car to clew
so its angle projects 50% up the luff. 3CHECK THE SHEET ANGLE
Sailmakers often add a line from the clew to show you the correct basic angle. With
this set, you can move the car forward to tighten the leech, or move if aft for more twist.EXPERT ON BOARD
Vertical creases in the luff means
the halyard is too tight. Horizontal
creases means the halyard is too
loose. In general, increase halyard
tension with wind strength