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post #1 of 10 Old 08-15-2012 Thread Starter
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Luff in the luff of main sail

I sail a J-22 and I've noticed that often when I'm sailing upwind, the main sail luff luffs, especially in heavy wind and I'm wondering what this is a result of. I've tried adding more backstay but the result is the same. Do I need to flatten the sail with more outhaul?

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post #2 of 10 Old 08-15-2012
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Re: Luff in the luff of main sail

You want some backwind in the mainsail luff. As long as the leech tell tales are streaming and not stalled, it's good.

The luffing is caused by the jib backwinding the main.

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post #3 of 10 Old 08-15-2012
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Re: Luff in the luff of main sail

The outhaul will help to flatten so that the sail isnt so easily 'backwinded'. Better is to slightly ease the jibsheet so that the 'slot' is operating at proper 'flow'; the stronger the wind the larger 'slot distance' between the main and jib is required; just the opposite when in light winds. You may also have to 'reset the location' of the jib fairlead car ... make sure that the jib luff is 'breaking' simultaneously along the entire jib luff after any other sail shape adjustment; although, if slight easing of the jibsheet doesnt correct the situation you may have no other choice but to move the jib fairlead car a wee bit more AFT (opens the jib leech).

Also too, tightening the backstay will cause the jib to become more 'draft forward' which causes the jib leech to 'open' and be further away from the main.

A little bit of so-called backwind is inconsequential, actually slight backwind may indicate perfect sail shape and trim .... so use your speedometer when making any adjustments to correct 'backwinding' as the highest speedo reading will validate 'perfect' sail shape and sail trim.

Last edited by RichH; 08-15-2012 at 01:04 PM.
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post #4 of 10 Old 08-15-2012
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Re: Luff in the luff of main sail

Last week I had a very experienced racing sailor ride with me. He was trimming the sails and I was driving. My main was luffing a little. When I asked him about it, he said "no big deal, look at the telltails on the leech." They were perfect. It was the best race for my boat yet.
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post #5 of 10 Old 08-15-2012
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Re: Luff in the luff of main sail

I race J-22's. Because there is no connection between the gooseneck and the tack on a J-22, you may need to apply a little (and I mean very little) cunningham just to keep the sail from creeping up the mast. Unlike big boat, J-22's are often vang sheeted in heavy winds, meaning that you need to take out twist with the vang and play the sheet to vary angle of attack. Applying backstay and outhaul help as well. The jib lead may need to move one hole aft (roughly 1-1.5 inch) which opens the head of the sail. Care should be taken to make sure the jib is not over trimmed. Look for a full time flying jib batten teletale and the skirt of the jib just inside the toerail. If there is no chop, extra jib halyard tension may also be needed to blade the jib a little. And as others have said, in the really heavy stuff, the fastest way up wind may be luffing the mainsail big time. The key is to keep just enough leech in the game to prevent lee helm so keep an eye on where the tiller ends up.

One other J-22 oddity. In gusty conditions the jib trimmer does a small ease before the mainsail trimmer which helps the helms take a bite and feather up.

Since there are no instruments on a J-22 (class rules) your best bet is to trim watching your point and speed against the nearest boat.

Despite their minor iteosyncracies, these are really super boats to race or simply daysail.

Jeff


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Re: Luff in the luff of main sail

Thanks for all the responses. It will take me a little while to read and digest, but if I have further questions, I'll add another reply. Thanks again.
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Re: Luff in the luff of main sail

You may want to check out Sail and Rig Tuning by Ivar Dedekam. It's a great book that provides easy to understand explanations for some rather complex forces. I've found it to be of great use.

Amazon.com: Sail and Rig Tuning (9781898660675): Ivar Dedekam: Books Amazon.com: Sail and Rig Tuning (9781898660675): Ivar Dedekam: Books

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post #8 of 10 Old 08-16-2012 Thread Starter
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Re: Luff in the luff of main sail

Thanks. I just ordered it.

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Originally Posted by Sabreman View Post
You may want to check out Sail and Rig Tuning by Ivar Dedekam. It's a great book that provides easy to understand explanations for some rather complex forces. I've found it to be of great use.

Amazon.com: Sail and Rig Tuning (9781898660675): Ivar Dedekam: Books

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post #9 of 10 Old 08-16-2012
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Re: Luff in the luff of main sail

We call it the "speed bubble".

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1973 Pearson 30 #255
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Re: Luff in the luff of main sail

Speaking of 'speed' and I was down at Pirates Cove in Galesville and it would appear that our very own 'Bubblehead' is listed in first place on their current beer-can race results. (That is you, right?) Congrats!


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