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-   -   mainsail mass confusion (http://www.sailnet.com/forums/learning-sail/43679-mainsail-mass-confusion.html)

HamptonMorgan22 05-29-2008 10:34 PM

mainsail mass confusion
 
I am new to sailing, and getting along quite well I think. I am starting to play around more with sail trim, my jib cars etc. However I am confused about my mainsail. It came with the boat so not sure if it is the correct fit first of all.

second. I have found 2 different measurements for my mainsail from 2 different databases. they vary 5 inches on the luft Mine is 1inch longer than the shortest measurement.

third who knows if my boat has the original mast or boom at this point. The last owner thought so but didnt know so who knows if the databases would even help at this point its a 1971 morgan 22

The mainsail I have comes about 6-10 inches from the top of mast. Depending on how hard I tension(no wench just me) If I I bring the sail to the top The boom falls in the grove of the mast where it can slide out unless I really really stretch it down.

So guess my questions are.
1. Is there a rule,suggestion,optimal position of the boom? Obviously it can not be set in the area designed for it to be removed. Should it be above/below? Should I set it for the sail I have already, the sail is in like new condition I would like to keep it if I can. If I leave it alone and let the sail be 8-10 inches from the top is that a big deal? Are people pointing and laughing at me? Or should I move the boom to accommodate the sail? Or get someone who knows better than me to measure it for a new mainsail? I do not know it that makes any sense I hope so. thanks for any help.

sailingfool 05-29-2008 10:48 PM

You need to tension (stretch) the luff of the mainsail, a little tension for light air, a lot for heavy air.

You should be able to raise the main halyard until twoblocked (to the top), then lean down on the gooseneck to stretch the luff (just like a winch would). You should have some form of a downhaul in place, a line that allows you to secure the gooseneck after stretching the luff. I would expect that a little tension gets the gooseneck back in the track.

Very little stretch for light wind, a whole lot of stretch for heavy wind. The objective of the stretching is to have enough tension so the max draft of the sail is at the middle of the sail when properly trimmed.

HamptonMorgan22 05-29-2008 11:24 PM

thanks I have been setting the downhaul to rest the gooseneck on the bottom of its rest, then tensioning the main with its haylard. I bet that will help with the weight of the boom to really tension it taught. So you think 6-8inches is a reasonably appropriate stretch length? I have only been out 7or8 times so far and unfortunately always seems to be very light to nonexistent winds. So I bet when I really tension it taught my sail is the appropriate luft length. Thanks

nolatom 05-30-2008 01:39 AM

You've explained the problem pretty well, but from what you've said, I don't know if you have the original mainsail (which should be properly tensioned along the mast without the boom (gooseneck, same thing for your purposes here) being in the open slot. But since it sounds like that's what's happening for you when you raise the main all the way up to the masthead, I suspect you're dealing with a replacement mainsail that's not designed for your boat.

What to do? Well, let's assume your mainsail, wherever it came from, is just 6-10 inches too short. If so, then what you've been doing (raising it as far as you can to get decent luff tension without putting the gooseneck into the open slot) is probably the best solution you have. In which case, just go sailing and don't worry about what others think, even if the peak of the main is 10 inches from the top of the mast. Within a foot or so, there's really no "proper" altitude for the boom, as long as the sheet and vang lead okay and you can duck underneath it when you change tacks.

Or you can shop for a new mainsail, which has the right luff and foot measurements for your mast and boom.

This help?

HamptonMorgan22 05-30-2008 07:03 PM

yes it does thanks a lot. It is a new sail so probably a combo of all of the above, I am not tensioning it enough, it will stretch some over time, and its probably a few inches short. But think I will live with it for now or may reconfigure the boom a few inches higher, I could use the few inches of ducking room.

PTsailing 05-30-2008 07:52 PM

We had this same problem with our new boat, raised the mainsail and it would stop several inches from the top, turns out we had a line too tight that was preventing the sail from going all the way to the top. :) oops, we're pretty new at this stuff. I wish I could tell you which line it was but I was at the helm when my husbands cousin (who actually knows how to sail) found the problem.

themcnasty 06-19-2008 09:08 PM

That would be the Cunningham, a line that is used to squeeze the bottom of the main sail together by pulling down on a spot a few feet from the bottom along the mast.

sailingdog 06-19-2008 09:21 PM

Actually, most sails don't hoist completely or fill the boom completely, since the spars are generally a tiny bit longer than the sail even when they're blown out.

BTW, the cunningham isn't used to squeeze the bottom of the mainsail—it is used to flatten the mainsail, by increasing tension on the luff.

zaliasvejas 06-27-2008 08:03 PM

Sailingdog,

From my dinghy sailing days.... tension on cunningham usually increases depth of the sail, making it fatter next to the mast. That you don't want when you are over powered. Tensioning outhaul and releasing any tension on cunningham will give you the flatest sail to sail in a breeze.
Unless, you are a MAN and you can take it.... ha, ha...

sailingfool 06-27-2008 08:23 PM

Quote:

Originally Posted by zaliasvejas (Post 334474)
Sailingdog,

From my dinghy sailing days.... tension on cunningham usually increases depth of the sail, making it fatter next to the mast. That you don't want when you are over powered. Tensioning outhaul and releasing any tension on cunningham will give you the flatest sail to sail in a breeze.
Unless, you are a MAN and you can take it.... ha, ha...

FWIW, its the outhaul that controls the depth of the bottom of the mainsail, the cunnigham is used to control the location of the draft. A growing breeze will pull the draft aft in the main, luff tension from the halyard and/or cunnigham should be used to bring the draft back to the middle of the chord.


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