Jib Leach curl.

Yara

Yara

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My jibs were suffering from leach curl, which was back-winding the main and horribly inefficient. Tried all the usual adjustments but to no avail. The leach cord was, however not fully retracted. Went for the brute force remedy. Tied the head of the sail to a tree, and rigged a rope around another tree, with a 4:1 boom vang purchase attached to the clew. Gently increased the stretch until the leach cord retracted, and bingo- no more leach curl!

Pretty agricultural engineering, and only recommended when all else fails.
 
As you have found leach curl is the product of too much leach cord tension. I am glad you have moved the leach cord however you may find the jib will still back wind the main a bit when hard on the wind. Just accept that.
Leach cord is there to minimise leach flutter. This can be very annoying sounding almost like a motor boat. The leach flutter is a function of the mass at the leach when looking through the chord of the jib. Battens are sometimes used to reduce the flutter. I have one jib from a large dinghy which was made with no hem or leach cord. The theory being that with no mass at the leach it would not flutter. Well it doesn't but it looks almost damaged with just a hot knife edge. Sometimes a sailmaker will cut a concave shape into the leach so that tension tends to load the leach to minimise flutter.
Flutter is also a problem on aircraft wing and tail trailing edges especially control surfaces. Except that in that case the surface flutters in increasing amplitude such that the control surface or wing depart in several oscilations (or milliseconds). hence you never see it ha !!!.
good luck olewill
 
On the UFO27 which I previously owned, I experienced similar problems. I cured the leech flutter by slightly tensioning the leech line but could not eliminate the back-winding of the main until I found that slightly easing the headsail halyard helped. The situation was further improved by winding in a turn or three of the enormous IRC-inspired genoa.
 
Yara said:
My jibs were suffering from leach curl, which was back-winding the main and horribly inefficient. Tried all the usual adjustments but to no avail. The leach cord was, however not fully retracted. Went for the brute force remedy. Tied the head of the sail to a tree, and rigged a rope around another tree, with a 4:1 boom vang purchase attached to the clew. Gently increased the stretch until the leach cord retracted, and bingo- no more leach curl!

Pretty agricultural engineering, and only recommended when all else fails.
Click to expand...

I thought I was suddenly dyslexic & stumbled on a gardening forum, about 'Peach Leaf Curl'!
 
nimbusgb said:
As I read that i half expected it to end with 'and the tree fell down' :) :)
Click to expand...

Dont know about that but at the end of the last season I did tie my spinnaker with both clews attached to the drive gate posts and the head attached to a cast alloy outside light boilted to thye house wall. Went in for a cup of tea and came back out to find the spinny and the wall light in next doors garden.
 
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