Stretch in an old sail!

When I set my outhal and other trim for a basic windspeed here say like 7 to 10 knots going upwind and have the draft I want, then when the gusts (15-20knots) comes the draft seems to be at least 20% deeper. The sail cloth, (Laser Class approved sail) looks OK and still "feels a bit greasy" when being rolled; it's very soft though.
I could compensate and set the sail for the higher wind speed but then I would lose a lot in the lulls which are for the most of the time.

This seems to be the factor that will make me get rid of it, not that the loss of its shape in itself is the big problem. I guess it would work for stable light conditions but those conditions wouldn't wear much on a better sail anyway, or would they?
 
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Yes Freddy,

not only does the sail stretch, outhaul line will also stretch and boom will bend (I don't have boom upgrade yet). You will have to play outhaul (vang and cunny also) through the puffs and lulls to keep draft position consistent.
 
The reason most people replace their sails is because the leech has permanently stretched. All boats point on their leech tension. It is obvious when sailing next to a new sail if your leech is shot they will point 3-5 degrees higher than you going up wind.

Regardless of the stretchy sail, you want to adjust the sail settings for the average wind speed not the gusts. Technique(hiking, steering, and trim) will maintain your speed through the gusts. It would be a fool's errand to constantly adjust the sail settings for a gust that lasts 30 seconds. The body movements alone would slow you down more than any gains by having a perfect draft.
 
Leech tension = point. A buddy sails an older laser, block to block, heavy vang and points 5 deg higher. He has also sailed and won on this boat for 20 years. He eats my lunch to weather. So much to learn...
 
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You can usually tell if you leech is done for as it will start to flutter in quite low wind speeds and you will get creases in the panels between the battens running parallel to the leech.

It does sound like your sail is pretty stuffed to me though and you should look to replace it.
 
You can usually tell if you leech is done for as it will start to flutter in quite low wind speeds and you will get creases in the panels between the battens running parallel to the leech.

It does sound like your sail is pretty stuffed to me though and you should look to replace it.

How can I tell if my sail is past its prime? Next time out, I will look at the leech like jeffers suggests, but are there other criteria?
 
How can I tell if my sail is past its prime? Next time out, I will look at the leech like jeffers suggests, but are there other criteria?

Stretch: How about by how much below the boom the foot is pulled when you haul on the cunningham hard? As for the outhaul, you should be able to pull it on so that you can just get 4 fingers stretch between foot and the boom at its halfway point.

Also, when the fabric feels more like cloth (bedsheets, they say) and less like plastic.
 
How can I tell if my sail is past its prime? Next time out, I will look at the leech like jeffers suggests, but are there other criteria?


The point of max draft moving aft (requiring more cunningham and sooner in the wind range to pull it forward again) This also has the effect of easing the leech.

The leech section (approx the last 30% of the chord when looking from luff to leech) will change from it's ideal shape of almost straight to assuming the same curvature as the middle of the sail

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Having thrown out all the scientific answers, the easiest way that I use is sailing against a known competitor with a new sail in med conditions (8-12) If I am slower AND pointing lower, it's time for a new sail. If only one of those conditions is true, it's usually the nut on the end of the tiller that needs a little adjustment
 
Thanks; the leech will get my attention next time out.
But can I just measure the length of the leech (sail on the floor), or are the sails too inconsistent for that to be meaningful?
 
It's what is happening to the cloth under load that causes a sail to deform from the ideal shape, and not easy to simulate that w/o actually having the sail on the mast, loaded up.
 

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