Optimist Tuning Guide
OPTIMIST SAIL TRIM
MAINSAIL
Mainsheet Trim : The mainsheet controls the
pointing and speed of the boat. A good rule of thumb for mainsheet trim is to have the
sail trimmed to the leeward comer of the transom. From that point you will be able to ease
a maximum of 5 cm for light air.
Telltales : Your North mainsail has two sets of
telltales along the luff and a telltale off each batten. In light winds or when trying to
accelerate, steer your boat so that telltales along the luff are streaming straight aft.
In medium winds with relatively flat water, steer the boat so that the windward telltale
is slightly stalled (usually angled up to 45 degrees) and the leeward telltale is flowing
straight aft. In heavier winds when the boat is overpowered, or where trying to pinch for
short periods, steer so that both telltales are just stalled. It is difficult to sail the
Optimist well with the actual luff of the main breaking in a complete stall.
Luff, leech and foot tension :
Boom Preventer - Luff
tension is primarily controlled by the Boom Preventer, or the line that attaches to the
boom jaw. Hook it on the "Preventer Peg" on the front of the mast, 15 cm above
the gooseneck. Adding or subtracting a twist on this line will raise or lower your boom at
the mast and determine your luff tension. If you experience scallops or horizontal
wrinkles off the mast, take a twist or two off. If you have vertical creases parallel with
the mast, add a twist. This sail control is often neglected, but it is very important to
establish proper sail. make sure that the Boom Preventer does not stretch at all. We
recommend using 4 mm spectra line.
Vang - The vang controls the luff tension
upwind and leech tension while sailing off the wind. The rope and wire for the vang should
not stretch at all. We recommend using 1.75 mm wire with a 6 mm Spectra tail for the vang.
The vang is a very important control line. If it is trimmed too tight, the leech will
stall and the boat will go slow. If it is trimmed too loose, the boat will go fast forward
but have no pointing ability. Below are some guidelines to help you adjust your vang. Try
these and mark your vang for the following settings.
•0 - 5 knots : Trim the sail to the corner of the
transom and cleat the vang.
•8 - 12 knots : Sheet the main until the boom is
centerline and 6 to 8 inches of the transom, cleat the vang.
•15+ knots : Sheet the main very hard until the boom
almost touches the transom, about 2 to 3 inches from it and cleat the vang. Do not ease
the vang in heavy air for downwind work. A loose vang will cause the boat to rock, go slow
and potentially capsize.
Outhaul : Never ease it more than 8 cm or
tighten it more than 4 cm from the end of your boom. The outhaul controls the depth of
your sail. A good rule is if you are able to point high, yet are going slow - ease the
outhaul.
Sprit tension : Before sailing, tension the
control line until there are slight diagonal wrinkles from peak to tack of your sail. In
very light winds these wrinkles will be barely visible, while in the heaviest winds the
wrinkles will be quite extreme. The goal is to set the sprit properly so that when sailing
upwind the sail is nearly smooth is all directions. If an extreme wrinkle develops from
the throat to the clew then more sprit tension is needed. If there are still wrinkles from
the peak to the tack, then the sprits is too tight.
Some sailors (especially the lighter ones) have found it advantageous to sail with the
sprit slightly looser than normal so that there is actually a slight wrinkle from the
throat to the clew. While this is not necessarily faster, it will flatten the upper part
of the sail and open the upper leech.
Remember to double check your
sprit tension before the start.
Since your sprit should be easily adjustable, it is best to ease the sprit slightly when sailing downwind, this allows the sail to relax and take a fuller shape. However, be sure at the leeward mark to re-tension the sprit for upwind sailing.
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