Sail Trimming

[rogern]

Don Gillette, Sail Trim Users Guide. Short, clear, step by step. Self published, so Google it. I recommend it all the time, get great feedback.

[Akka]

Mainsail: Sew telltales on the leach of the sail, fairly high up. Ours are just below the top full batten. When reaching, you want those telltales to be streaming in the wind with maybe an occasional duck behind the sail. If they droop down or hide behind the sail, you are over-trimmed and should release some sheet.

When broad-reaching, downwind to the point where you cannot get flow across the main (I.e., those telltales droop no matter how far you let the sail out), the best trim is with the boom perpendicular to the apparent wind.

When close-hauled or beating to windward, the boom should be inside the boat, and depending on the boat, close to or on centerline. On our boat, which is reasonably good upwind, weactually bring the boom just to windward of centerline. Tighten the sheet until the top of the leach is parallel to the boat's centerline. Those leach telltales should duck behind the sail from time to time, but if they stay back there, ease out some mainsheet until they stream again.

Jib: Put 3 sets of telltales on both sides of the sail, a foot or so back from the luff: one set high up, another about halfway up, and the third 6 feet above the deck. You want these telltales to be streaming back or the inside (windward) telltales lifting (breaking) without luffing the sail. If the outside telltales lift or both telltales droop, you're over-trimmed -- ease the sail out until they fly again.

If you can adjust your jibsheet leads, move them forward if the top telltales are breaking when the bottom ones are streaming and back if the opposite occurs.

Contrary to popular belief, a cruising boat should sail with the jib undertrimmed slightly, maybe even with a little bubble showing on the leading edge. This makes the boat much easier to sail in response to changes in wind direction and speed. If the wind lifts (i.e. rotates toward your windward side) the sail will fill and power up, the boat will heel a little and turn automatically toward the new wind. Conversely, if the wind heads you, the sail will develop a bigger bubble, the heel will decrease and the boat will bear off. The same with strength -- a puff will heel the boat, rotating it toward the wind in any case, but the undertrimmed jib will immediately luff, reducing that heel and preventing the boat from rounding up uncontrollably.

[pyroray]

Originally Posted by Hudson Force

The shortest version:

Adjust so the tell-tales are streaming aft & when in doubt, let it out.

This was the first advice I learned, and followed, and felt and listened. I don't even have Telltale's anymore.
My lesson to you, learn to feel the wind. Start by closing your eyes and point your nose into the wind. Practice, practice, practice.

[ctl411]

Sail power by Wallace Ross is my favorite. Covers all from basics with pictures to building a polar chart for your own boat. This is the one book out of literally totes full that I have that I recommend.

[Hudson Force]

Originally Posted by pyroray

This was the first advice I learned, and followed, and felt and listened. I don't even have Telltale's anymore.
My lesson to you, learn to feel the wind. Start by closing your eyes and point your nose into the wind. Practice, practice, practice.

Most boats of any size have much to disturb the wind by the time it reaches the helm. Pyrory's advice is wise, but there's often much more or other clues when you're not at an open helm. There's the lift of the windward rail; the wisps of wind lines and cat's paws on the water; ripples and glassy spots on the water; the wind on the water and 15 feet above the water; certainly there is the knotmeter too. Telltales on the sails are often mentioned in posts above, but there's also much to be said for a masthead vane or some bits of yarn on the upper shrouds. In addition, there is another vector at play. The set and drift of the current has a greater effect and variation in coastal and inshore sailing,- this can't be overlooked. ...and the changes in wind coming around a point or off a high shore.

Pyrory wisely says, "learn to feel the wind", but I would add that you gain much by learning to sense much more in your surroundings. 'probably not easily read in a book.

[Jim Cate]

Hudson, one of the things I find most difficult to deal with in sail trim is the (sometimes quite large) differences in wind strength and direction between masthead and sea level. Having instruments, pennants, yarns etc at several heights helps to understand what is going on, but actually tweaking the sails to take advantage of those differences often defeats me. I suspect the ability to do that well is one of the earmarks of a great helmsman. Usually easier at sea than in coastal situations, and in places like the D'EntreCasteaux channel where we are now it is really complicated. I find it quite frustrating!

I suppose that if it was easy, everyone would be out here sailing...

Jim

[Suijin]

In my experience it's not so much about "feeling the wind" as it is "feeling the boat", at least when it comes to sail trim, vs. helmsmanship and reading the water.

Virtually every boat, when it's trimmed properly, you can feel it slip into "the groove" and accelerate. Very small changes in various trim controls can have an outsize impact on boat speed.

That's one reason, when racing, that trimmers are always at work, always adjusting, experimenting. On some legs you never even cleat your primaries; you're always working them. I trim main usually when I race and it's exhausting... I have either the mainsheet or the traveller in my hand and the other on my knee and it's work work work.

Obviously, racing is an exaggeration compared to cruising, but the initial premise is the same; continue to make changes until you have the trim "dialed in".

This is a great video, showing world-class sailors at work on J Boat. The take away is that no one has the right answer right off the bat; they tinker for quite awhile until they are satisfied with how the boat is moving.

There's a lot of introductory material on trimming using various sail controls, but the section that illustrates my point starts at 16 minutes, when they actually start racing:

https://www.youtube.com/watch?v=P1n-7czmc14

[Stumble]

Originally Posted by Jim Cate

Hudson, one of the things I find most difficult to deal with in sail trim is the (sometimes quite large) differences in wind strength and direction between masthead and sea level. Having instruments, pennants, yarns etc at several heights helps to understand what is going on, but actually tweaking the sails to take advantage of those differences often defeats me. I suspect the ability to do that well is one of the earmarks of a great helmsman. Usually easier at sea than in coastal situations, and in places like the D'EntreCasteaux channel where we are now it is really complicated. I find it quite frustrating!

I suppose that if it was easy, everyone would be out here sailing...

Jim

This is all about twist, serious three axis (at least 2) twist control is the only way to get it right. Usually the main is mostly right thanks to the traveler (2nd axis twist control), but the jib is somewhat left alone, just getting by with the sheet. Because jib lead an are set on tracks based on their hard on the wind best location, any time you ease off even just 5 degrees you really need a barberhaul to move the lead outboard a bit.

It's a massive difference in sail control and speed.

[NoDramas]

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