Submitted on November 23, 2005 by Jack Montani

Question: I just purchased of a loose foot / partial batten main back at the end of summer. Previously I was using a full batten / closed foot main sail on my Catalina 36. The new main is a great sail when the wind is up but I am struggling to get the new main to perform in light air. It seems that it is delivering less power than my full batten sail would provide at lower wind speeds (less than 8mph). What should I be looking for in terms of up wind trim (twist/draft set) to get more performance out of my new main?

Thanks,
Jack

Answer: Jack

The new sail is in all likelihood flatter than your old one. The old sail probably got deeper with age. To get the same power out of your new sail you will need to Power Up the new sail. Here's how: Hoist the halyard just short of firm. Leave a wrinkle or two. Do not stretch the sail. Ease the outhaul to get perhaps 8 to 10" of depth in
the foot. Don't get carried away with this - just let the sail take its designed shape. If you have an adjustable backstay then ease the backstay to straighten the mast. From there, trim the mainsheet just short of a stall. Here's How: As you trim in the mainsheet you take out twist. The telltale at the top batten should be flowing. As you
trim the mainsheet the telltale will start to stall some of the time. Best trim is between flowing all the time and stalled half the time - you'll need to experiment depending on the wind speed and sea conditions of a particular day.

You may also need to re-tune your mast for the new sail. If the mast was tuned with pre-bend for the old sail, then you may need to take the pre-bend out by tightening the lower shrouds. (Pre-bend is bend tuned into the mast to match the shape of a mainsail. With older sails which grow deep extra pre-bend can help remove some of the excess depth.)

Good luck,
Bill Gladstone
www.northu.com
ph - 203 245 0727

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