Problem Solving with
You are going well. The boat is flying and
you are with the pack. Then, quite horribly suddenly, and often without
your apparently altering anything, it all changes. To leeward, boats point
higher and go faster, and the windward boats start to roll over you.
So, what has happened? Why are things going
wrong and what can you do about it?
Firstly, don’t panic. You were going
well and can do so again, providing that you are logical.
So, identify whether it's a pointing
problem or a speed deficiency and then apply a check list
Don't forget to
alter one thing at a time only, and to give the change time to work.
You need to point higher...
Q: Is the mainsail leech too open?
Answer: Try tightening it by
Use the angle of the top batten to the boom
as your guide. Ideally, it should be parallel to the boom. The top windtuft
should, in fact, be streaming aft most of the time. But stalling it, up
to 40% of the time, should give the best pointing ability, although at
the expense of speed.
increasing main sheet tension
increasing kicking strap tension
bringing the boom closer to the centreline
Q: Is the mainsail too flat?
If the mainsail is too flat, the leech is
likely to be too open and the slot between the foresail leech and the front
of the main too wide. A good guide here is: If the main luff does not backwind
in medium conditions from time to time, then the mast is too bent. Also,
the sail can have large diagonal creases which in extreme cases will flutter.
Q. Is the foresail too full at the luff?
ease clew outhaul
Identify this problem by luffing up rather
more than usual to see if the whole luff length collapses at the same time.
Increasing the rig tension (Al’s note: = jib halyard
tension) straightens out the angle of attack, it is possible
to go too far and make the sail difficult to "read". (Al’s
note: at this point, windtufts on both sides of the jib would become very
‘jumpy’ and you would have trouble settling into a groove where the jib
is neither luffing nor stalling)
increase rig tension
ease luff cunningham until luff has minute wrinkles
move fairlead closer to the centreline
Q: Is the foresail leech too open?
This problem shows itself when lufling up
more than is usual. If the top windward windtuft collapses first, tensioning
the foresail halliard reduces rake, raises the clew and so tensions the
sheet foresail harder
move fairlead forward
reduce mask rake
increase jib halliard tension
Q: Is the Helm too neutral? Has it
Some "feel" is necessary to the helm in
order to keep the boat on track when the helm is looking elsewhere. Up
to 70% of windward concentration is spent in anticipating what changes
in the environment are about to affect the boat.
increase mast rake
sit further forward
angle centreboard forward
one adjustment at a time, waiting a while to see if it makes an improvement.
You want to go faster...
Q: Is the mainsail too full?
In a breeze the very best speed seems to
come when the top quarter of the sail has very little curve and will seem
almost straight when viewed from below. The top telltale will stream all
Aim to make the sail inert in the gusts, so
that it gathers rather than flaps.
bend the mast more
tighten the clew outhaul
Q: Is the mainsail leech too tight?
Signs that the leech is too tight are excessive
and uncontrollable heeling in gusts, associated with sail being too full
and so there could also be massive backwinding.
Q: Is there excessive weather helm?
increase mast bend
ease boom away from centreline on the main sheet/bridle/traveller
This problem shows itself particularly in
gusty conditions when the out of balance boat tries to luff into the wind
as the gust hits. Keeping the boat flat and moving aft not only keeps the
hull shape symmetrical but also makes best use of the fatter flatter aft
Q: Is the foresail angle of attack too shallow?
keep boat level and do not allow it to heel
move crew weight aft
raise centreboard a fraction
If the angle of attack is too shallow, the
sail is not only difficult to read but the centre of effort goes aft. When
this happens the bottom windtufts become unstable as first the windward
one and then the leeward one stall out as the airflow rapidly fluctuates
from one side of the leading edge to the other.
Q: Is the foresail leech too tight?
reduce halliard tension and/or
reduce rig tension overall
tension foresail cunningham
move fairlead outboard
This shows as excessive mainsail backwinding
and the lower windward windtuft collapses before the top one. Aim to keep
the middle leech parallel to the centreline with the leech at 3/4 height
being 5% - 10% open and the leech at 1/4 height being 5% - 10% closed.
Tiny movements of sheet and fairlead adjustment have massive effect on
the leech so don't overdo them.
ease sheet slightly
move fairlead aft slightly
increase mast rake
As a general rule flatter is faster,
while a tighter leech improves pointing.
By working through these adjustments, it
is possible to bring the boat's performance back on track. Don't forget
to wait a moment after each adjustment to see if it helps.
UKWA News 1995