As soon as the sail plan changes, so does the
handling. Balancing the sail set correctly will
allow the yacht to sail with little requirement of
the rudder.
In an ideal world when the wind is hitting each
sail with the same force, the sails should steer the
boat and the rudder merely guide it along its path.
Going upwind and when the sails are balanced the
rudder should feel light and have just a small
tendency to head up into the wind.
If the rudder is pulling hard one way or the other
to stay on course the sail balance is probably
incorrect and the excess rudder is slowing the boat.
How yachts pivot. Achieving the balance
Yachts pivot under sail. How they pivot depends
on the relationship between the sail area above the
waterline and that of the underwater profile of the
boat. The central point of the underwater area is
known as the centre of lateral resistance (CLR) and
this is the pivot point. It is often just aft of the
mast.
The forces produced by the wind on the sails are
focused to a mid-point in the sail plan, the centre
of drive (CD).
Depending on the sail set, pressure on the sails
will either balance or rotate the boat around this
pivot point (CLR). When the sails are balanced, the
CD is in line with the pivot point allowing the
yacht to sail straight with little requirement of
the rudder.
The balance is changed by too much pressure in
one of the sails either when the wind increases,
when reefed or when the boat is sailing with just
main or genoa.
Main sail pressure
When sailing with too much mainsail or just the
main the CD moves behind the pivot point causing the
boat to head up into the wind. This explains why it
is hard to bear away with the main pinned in hard;
the only solution is to ease the main before bearing
away.
If sailing with just a mainsail or too much
mainsail, to counteract the pivoting effect of the
sail and sail a straight course, the tiller or wheel
is steered to weather giving weather helm, slowing
the boat.
Genoa pressure
When sailing with just a genoa, the CD moves in
front of the pivot point, pulling the bow downwind.
To counteract this tendency the tiller is pushed to
leeward giving lee helm, slowing the boat.
However, a large overlapping genoa, with sail
area coming behind the pivot point will start to act
like a mainsail as the overlap is helping turn the
bow into the wind.
Boat heel and pivot point
When a boat heels to leeward, the sail plan and
CD moves to leeward of the pivot point. Because the
sail plan is driving forward it is also
rotating around the pivot point and makes the boat
turn into the wind.
Conversely, if windward heel is induced, the boat
turns to leeward as the CD moves around the pivot
point.
So as the boat heels to leeward, weather helm
increases from both sail pressure and the CD moving
to leeward of the pivot point below.
Listen to the boat…
If the boat is trying to turn into the wind try;
- De-powering the mainsail using the traveler,
sheet or reefing.
- Reducing leeward heel
- Reefing the genoa if is a large overlapping
type
- Increasing the genoa – so long as this does
not make you heel more.
If the boat is turning away from the wind;
- Reduce the genoa, ease the sheet
- Increase the mainsail
- Ensure you are not heeling to windward
As soon as the sail plan changes, so does the
handling - so listen to what your boat is telling
you… Sail the boat without excessive heel and keep
the sail plan balanced as you reef.
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Nieuwsbrief
