Jib instability

I have a 21SE and when the winds are above 12mph or so and we seem to be tuned perfectly are really flying, the leach of the jib starts to flap wildly. When the winds were up to around 18 mph the jib sounded like a helicopter. This can't be efficient. I believe I have the jib traveler tuned correctly so that the upper and lower tell-tales are breaking at the same time. I also have tightened the leech line on the jib and I could always crank this more, but this is tight already. I have not adjusted the uphaul on the jib, yet. I basically set the uphaul and leave it.

In the lighter winds I have been able to control this by having the traveler and leech lines tuned correctly, but as the winds increase the flapping becomes more violent.

Has anyone been able to correct this? What measures should I use and in what order should I execute them. How critical is the uphaul on the jib? The tension on the jib uphaul looks good so would more or less be best? Any other ideas? I think new sails are in my future........

Thanks as always!

A leech line will help tame the jib in higher winds. Also, if you have a multi-point clew plate attach the jib sheets to one of the higher points.

Click on the link for a common answer to your problem.

viewtopic.php?f=14&t=6983&hilit=winner

(I bought a new jib and fixed my problem)

Thanks skipshot. All indicators are telling me a new sail is in order. I talked with a friend who used to race Stilettos on the open circuit and he said same thing. Usually you wear thru two jibs for one main. He also said a flat sail does not viberate. I have the original main I believe, but know my jib is not. You can also see that it is blown, but thought there may be other tuning options other than the leech line to help reduce the flutter. I can mostly tame it with the leech line. but the cupping of the sail is getting more pronounced. The helicopter will need to happen until fall or winter and then order the big square top with matching jib. I really can't wait

Thanks!

I found that the leach on the 18 will flutter in higher winds, if you dont have the jib cars far enough back. Take the jib cars to the very back of your track and see if that helps.

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1992 Hobie Cat 18 #16943
Hobie Fleet 198, Rapid City, SD