Sail Trim

[Ed Nye]

Question. I know that for the best results in determining sail trim jib tell-tails should be attached about 12 inches aft of the luff. You can see the windward tail and you are supposed to be able to see the shadow of the leeward one. What I want to know is, if you can't see through the sail to see the leeward tail, can you add a luff tail to act in its place and what should you see when the jib is trimmed properly?
Ed

[Dan McCosh]

Not sure what a "luff tail" is, but the idea of telltails is to note when the air is attached to both sides of the sail. The telltails are about 20% of the chord back from the leading edge since that is usually where separation takes place. When all is well, both fly evenly. Separation makes one or the other point up or even forward. If you can't see through the sail, the usual solution is to install a clear vinyl window. It's unusual not to at least see a clear shadow, however.

[Venchka]

On my first main & jib I used red yarn for tell-tails. They worked well EXCEPT-I didn't know what I was doing and located them too clode to the seams. The yarn would snag on the seams and not fly freely sometimes. Visibility was fine on 4oz white Dacron.

[ahp]

Sometimes the sailmakers will put a little window in the sail so you can see the telltail on the side away from you. I found with white dacron sails windows were not necessary. Mine were "Wintails" with a stick-on disk and about 12 inches of orange ribbon. No problem.

[TEWK]

Stick-ons are available from lots of sources - most marine suppliers without naming names. If I wanted them, that is where I would go.

All they indicate is the direction of airflow across the face of the sail. If they are straight back, that is best. In theory, both sides will be straight back. It is important if one is racing perhaps, but I seldom pay much attention to them. I have learned to look at sail 'shape'. There is an awfully lot to sail trim and the tel-tails don't tell even the expert if luff or foot tension is correct, where to move the sheet blocks, forward - aft, is the leech too tight? Too little belly or too much? and etc.

[ 09-17-2003, 07:59 PM: Message edited by: TEWK ]

[Todd Bradshaw]

Actually, telltales are one of the best ways to determine fore and aft jib lead placement. If the lead's position is correct, both upper and lower telltales will break at the same time if you begin a tack or head up too high.

[J P]

Ed, here's a link to some good info on telltales.

http://www.wb-sails.fi/

John