Sail Trim

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Triton106
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Joined: Fri Apr 18, 2003 4:51 pm
Location: San Francisco Bay Area

Sail Trim

Post by Triton106 »

Most people are familiar with the strong wind and wave conditions on San Francisco Bay in the summer months. However, not too many sailors know about the light wind conditions during the winter months. For example, for the last several weeks the wind strength has been in the range of 0-10KT with guts to 15KT. To sail efficiently on the bay with our plastic classics and aging sails requires us to be very skilled at sail trimming which I have not paid much attention to until now. Since many forumites sail on the east coast and maybe southern california I hope to learn from you guys.

I have also been reading sail trimming books and articles such as Annapolis Book of Seamanship and Chapman Piloting but they are not easy to understand and summarize in simple and easy to remember ways. So could someone tell me -

In 0-5 KT wind sailing to windward - how should I sheet the main and jib. Where shold I place the boom and jib car? Where should I place the traveler car? How tightly should I sheet the boom vang, the main downhaul? How do I use telltails?

In 5-10 KT wind sailing to windward - same questions.

In 10-15 KT wind sailing to windward - same questions.

Thanks very much in advance for your time and insights.
Ray D. Chang
Triton 106 in Berkeley, CA
radicalcy
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Re: Sail Trim

Post by radicalcy »

Ray,
Not to avoid answering, but if you go to Sailboatowners.com there is a sailtrim forum run by Don Guillette (sp?) He can answer all your questions, and as well has a sail trim quick guide for sale. I have it, and it's great!!
Larry Wilson
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Paulus
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Re: Sail Trim

Post by Paulus »

This site has some answers...

http://www.sailingusa.info/sail_shape.htm
Triton106
Candidate for Boat-Obsession Medal
Posts: 392
Joined: Fri Apr 18, 2003 4:51 pm
Location: San Francisco Bay Area

Re: Sail Trim

Post by Triton106 »

Thanks Larry for the tip! I already posted the question there. I will post any helpful responses on this forum.

Thanks Paulus for the link to USA Sailing. I have skimmed the material over before. Like other sailing websites their treatment of the subject is a bit more high level than what I need.
Ray D. Chang
Triton 106 in Berkeley, CA
Paulus
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Re: Sail Trim

Post by Paulus »

The simplest answer is that when going to wind, one sets the jib first to where it is full and just "in" from luffing - i.e. once on course, let the jib out to where the leech starts luffing, or "flagging" and pull it in just enough to get it to stay full and smooth.

Second you do the same with the main sail - let it out to luffing and pull it in to where it just takes shape without flagging.

This assumes the sails are somewhat in good condition and not "blown out", - if they are, chances are they will always luff somewhat - which can be controlled by shortening the leechlines a bit (thin lines sewn into the leech of the sail that can be pulled and locked into a plastic camcleat also sewn onto the leech).

Going from stiff winds to lesser windy conditions, one would want to power up the sail by loosening the cunningham (or simply not raising it as tight on the mast track as usual), thus creating somewhat of a baggy sail, and doing the same with the outhaul - don't stretch the sail onto mast and boom, but rather let it loose a bit.

When trimming a powered (loosened) sail, make sure the deepest part of the "pocket" is about at 35% to 40% distance from the luff (back from the mast or the forestay); further aft than that would put most of the power towards heeling.

As the wind increases, you would de-power the sails by tightening the luff (haul it up tighter) and putting more force on the outhaul. The pocket can be controlled by puling or loosening the cunningham (line pulling the tack, or bottom forward part, of the sail down toward the boom) and, it you have one, tightining or losening the adjustible backstay. Tightening the backstay would pull the pocket forward; tightening the cunningham would move the pocket aft.

I am sure I have made enough controversial statements here, to cause others to actually chime in now...

heh, heh, heh...
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