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-   -   Flapping leach (http://www.sailnet.com/forums/learning-sail/29020-flapping-leach.html)

mwrohde 02-11-2007 01:07 PM

Flapping leach
 
I bought my first boat about three months ago. It's a Cal 3-27. I sail on a lake in north Georgia.

The last couple of times I've been out I've noticed that the leach on the mainsail flaps or flutters. I don't know if it's always been doing it and I'm just now noticing, or if it just started doing it. Given how little I know I'm sure it's operator error, but I can't seem to get it to stop.

This happens close hauled or on a broad reach, or anywhere in between. It happens more with stronger wind and stops completely in light wind.

Any help is appreciated.

Matt

Giulietta 02-11-2007 01:10 PM

MW welcome to Sailnet...

You should have a small cable that runs along the leech of your sail from the top down, and ends in a small cleat.

Tighten that cable (pull down) to provide more support to your leech, till it stops fluttering. Then just release it around 1/4" and cleat it. Keep doing till it stops.

If you don't have one, and your sail has deformed it self slightly, get one done, its pretty easy, too. you can do it or ask a sailmaker to do it for you...
Bellow a photo of the cleat and leech line.

http://i125.photobucket.com/albums/p...sc/LEECH-1.jpg




G

johnsail 02-11-2007 02:14 PM

Jib leads and leech cords
 
This sounds like either a leech cord or a jib lead problem. Either way, it's a simple fix.

If tightening the leech cord (cable) inside the leech (the sail's back edge) doesn't do the job, the jib sheet's too far aft. Move the block (called the lead -- "leed") forward. You'll notice that the jib leech straightens.

The best way to gauge that the lead is set properly is to have three pairs of telltales (lengths of yarn or ribbon) evenly distributed near the luff (forward edge) of the jib. When the lead's set right, the three telltails on the windward side of the jib should all be doing the same thing at about the same time. If you're trimmed correctly, they'll all be streaming straight aft simultaneously. On most jibs, when the lead is colrrect for sailing to windward, it's too far aft for reaching.

Luff telltales don't work on a mainsail because the air flow there is disturned by the mast.

sailingdog 02-11-2007 03:08 PM

Quote:

Originally Posted by johnsail
This sounds like either a leech cord or a jib lead problem. Either way, it's a simple fix.

If tightening the leech cord (cable) inside the leech (the sail's back edge) doesn't do the job, the jib sheet's too far aft. Move the block (called the lead -- "leed") forward. You'll notice that the jib leech straightens.

The best way to gauge that the lead is set properly is to have three pairs of telltales (lengths of yarn or ribbon) evenly distributed near the luff (forward edge) of the jib. When the lead's set right, the three telltails on the windward side of the jib should all be doing the same thing at about the same time. If you're trimmed correctly, they'll all be streaming straight aft simultaneously. On most jibs, when the lead is colrrect for sailing to windward, it's too far aft for reaching.

Luff telltales don't work on a mainsail because the air flow there is disturned by the mast.

Ummm... maybe you should read the original post again...where it clearly states it is the mainsail leech he's talking about.. .Giulietta has a good answer and diagram for him though, so I won't bother answering it myself. :rolleyes:

One thing I would want to mention is that if you have a topping lift attached to the boom, that you make sure you've slacked off on it so that the boom isn't supported by it and not the mainsail. If the topping lift is supporting the boom, it will cause the mainsail to not shape properly and the leech will tend to flog, even when the sail is trimmed properly, since the sail's shape is wrong. In Giulietta's photo, the topping lift is probably the very slack black line meandering down the leech of the mainsail.

mwrohde 02-11-2007 07:34 PM

Thanks, fellas.

I don't think I have a leach line. I'm pretty sure I'd have noticed that, but I'll look again.

I know the topping lift is slack. I know that because I forget it every time I raise the main. I get to sailing, look up and say "Damn, forgot the topping lift again". Then I point her back into the wind and release the topping lift.

Now, about this leach line . . . I can't tell from the photo, but it looks to be embedded in the leach of the sail. Is that right? Also, it doesn't look like the cleat mentioned is on the boom. Where is it?

It looks like that sail has some plastic accoutrements attached to it. Mine does, too, with nothing attached to them. Is that for the leach line?

Edit: Giulietta, I've been lurking a while and feel like I know you. I love your sense of humor. Thanks for the help. SailingDog, I've read a lot of your posts, too. Thank you.

SailorMitch 02-11-2007 08:16 PM

Yes, that plastic accoutrement is probably the clam cleat that would be used to tighten the leech line. Now look for a narrow pocket straight up the leech from that plastic cleat -- the line goes inside that. Perhaps you can rig another one yourself. Use something like an electrician's fish tape for the job. Use some small diameter line for it, and make sure it fits properly into the clam cleat before you go to the trouble of running it. I'm not sure how the line is terminated at the head of the sail, so perhaps someone else can answer that one?

Or -- take it to a sailmaker to have one added. As you are discovering, it is a useful sail control.

sailingdog 02-11-2007 09:22 PM

The cleat is usually a plastic clamcleat that is directly attached to the sail, and the leech line does run up along the leech of the sail, usually in a hemmed over pocket. BTW, it usually is a fairly light line.

Giulietta 02-12-2007 10:55 AM

Quote:

Originally Posted by mwrohde
Giulietta, I've been lurking a while and feel like I know you. I love your sense of humor. Thanks for the help. SailingDog, I've read a lot of your posts, too. Thank you.

You know me?? Have you been in Cascais?

Its not sense of humor, I am like that since birth....guess someone dropped me head first....:D :D

Wanna be my friend??? Bash CD's boat.....:D :D :D

hellosailor 02-12-2007 11:06 AM

Tension on the mainsail outhaul should shape the leech of the main, in the same way that tension on the jib car shapes the leech of the jib, no?

So adjusting the tension on the outhaul might also deal with the leech fluttering?

sailingdog 02-12-2007 11:46 AM

Tension on the foot of the sail can help flatten the sail shape, but may or may not help with the shape of the leech. Unlike the tension of a jib car, the tension of the outhaul is primarily outwards, with very little downwards component. By moving the jib fairleads you actually alter the vector of force acting on the sail by changing the angle of the sheet. The boomvang would have more effect on the leech of the sail than the outhaul IMHO. However, if the sails are a bit older and a bit blown out, the boom vang and outhaul won't do much at all, and you really will need to use the leech line then.


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