Tuning and Sailing a Sigma
33
by David Robinson,
Sobstad Sailmakers (UK) Ltd
(This article was first published in the 1985 Sigma 33 yearbook, long before Genesis sails were introduced, but most of it remains as true as ever.)
Mast rake
Should be aft
between 8 and 12 inches at the lowest black band with the backstay
slack.
Rigging tension
Tight rigging
important. Backstay to give 4 to 8 inches of mast bend between the masthead and
the gooseneck. Then take slack out of shrouds. This will give about 3 to 4
inches of permanent bend with the backstay slack. Do not overtighten the cap
shrouds.
In winds of 15 to 20 knots, use a strong hand to pull on the
backstay, or lead the backstay control line to the weather sheet
winch.
Sail carrying
The following is
a rough guide:
Sails set
.................................................................Wind
speed
Full main and No 1
genoa..........................................0-12 knots
Full main with
leach cunningham and No 1................12-18
Main with one reef and No 1 or
full main with No 2...18-22
Main with one reef and No
2.....................................22-26
Main with two reefs and No 2
...................................26-30
Main with two reefs and working
jib..........................30-35
Main with three reefs and working
jib.........................35-40
Mainsail trim
In three quarter
rig, the mainsail is the most important sail on board and, in variable
conditions, needs to be constantly adjusted for maximum speed. The controls are
as follows:
Backstay: use to increase fore and aft bends and
flatten the mainsail to enable it to be used in heavier winds. This will also
tighten the forestay and improve pointing.
Luff tension via
halyard and cunningham: moves the flow forward, freeing the leach for strong
winds.
Mainsheet: controls twist: the tighter the sheet, the
tighter the leech and the less twist: reduce twist as the wind
increases.
Leech cunningham: controls the flow in the foot
and has flattening effect: use it as soon as the yacht becomes pressed under
main and No 1 genoa.
Mainsheet traveller: controls the
sheeting angle but keeps the mainsheet tension constant. Set to leeward allows
yacht to sail more upright but to fall off to leeward. In light airs, set to
weather and ease the mainsheet.
Do not oversheet in light winds.
Keep the leach tell-tales streaming, especially the top one. As the wind
increases, sheet harder and reduce twist. Keep luff tension low and leach
tension high to keep flow aft and optimise pointing.
For medium
winds (8-18 knots) flatten the main with mast bend and leech
cunningham. Increase luff tension to keep the flow forward. Backwinding is
acceptable near the mast but, if it extends further aft than halfway, reef or
change headsail. In gusty conditions, ease the traveller. Keep
the backstay very tight.
Reaching: play the kicking strap
and mainsheet all the time. In gusty conditions, keep the kicking strap very
tight and play the mainsheet. Ease both kicking strap and mainsheet if in danger
of broaching.
Running: set as full as possible by easing the
main halyard until horizontal luff creases just appear, easing the clew outhaul
and easing the backstay to zero tension.
Gybing: it pays to
tack downwind. Prevent the spinnaker wrapping itself round the forestay by
gybing the mainsail only after the spinnaker pole has been reconnected to the
mast. Gybe by end-for-ending the pole rather than dipping.
Headsail trim:
No 1 genoa
sheeting is limited by the width of the spreaders and there should be a 2 or 3
inch gap betwen the sail and the spreader end. In light airs, barber haul the
clew inboard.
The No 2 genoa and working jib can be sheeted in much harder
until the leech is just off the shroud, thus improving pointing.
Tack
changing always pays if you are on a tack with the windward halyard
free and tactics do not dictate otherwise. Attach the new genoa to windward of
the genoa in use and use the weather sheet of the old genoa as the (new) working
sheet of the new one. Hoist the new genoa inside the old one as quickly as
possible and, as soon as hoisted, tack the yacht. release the old genoa sheet
and hand the sail, transferring the old sheet to the new sail as the weather
sheet. Make sure all halyards are free to run.
Spinnaker trim
The two
spinnakers provided are a working tri-radial and a heavy limit tri-radial. The
working tri-radial is intended as an all round close reaching, broad reaching
and running sail. Foot width is reduced to push more of the sail in plan view
from behind the miansail when running, so keep the foot setting loosley with the
bottom panels undistorted and pulling well. Keep the clews level by adjusting
the pole height. Hoist the spinnaker behind the genoa and do not pull round with
the guy until the halyard (which should be marked to prevent under-hoisting) is
fully home.
Crewing
Use the crew for
sitting out. Only the lightest person should go on the foredeck or adjust
rigging tensions and so on. Off the wind, do not drag the stern by having too
many crew aft.