Vibrating jib..?!

[kilkerr1]

Ello all

Had a great days' sailing this Saturday, Thames Estuary, Medway etc. Much fun was had bounding (for us - I use the term loosely) along to windward in Santa Teresa, and we got up to about 5 knots, which, for me, was most exciting. However, the closer to the wind we got the jib would start shaking, sort of vibrating, once so much that the entire boat (22ft) vibrated slightly too. We tried tightening the sheet more, easing off, all sorts, but the thing kept thrumming away in a very strange way. It was worse when on a starboard tack, strangely enough. So - I'm pretty sure it's not meant to do that. We're still quite new to all this and I'm sure there's a simple explanation, but it's eluding us at the moment! Any ideas?

Cheers.

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[Robin]

It's caused by a slack leech to the sail, check the fairlead isn't too far back (if you have telltales all should lift together, if you haven't then fit some!). If the fairlead is correct there should be a leechline cord that you can tension JUST enough to stop the flapping. Otherwise you may have a stretched sail, sailmaker may be able to improve it for you.

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[alan]

I would agree with Robin, that it is probably caused by a slack leech: tighten up the leech line until the leech just stops "flapping".

<hr width=100% size=1>Alan Cloke

 

[kilkerr1]

Fab, thanks. Seems like it's a simple one everyone knows - except me! So much to learn, so little time...



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[bob_tyler]

Be careful not to overtighten so that the leach curls. This will lose efficiency.

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[AndrewB]

Jib 'motoring' (as others describe) sounds the likely cause but doesn't usually affect the whole boat. To be on the safe side, particularly if you have a jib furler, check that the rigging tension is sufficient. (Easiest is to compare with similar sized yachts - a surruptitious twang as you pass by in the marina. Go with the tautest, cruising rigs are rarely over-tight).

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[ashanta]

Try tightening the forestay. The forestay should be at it's tightest when beating. Do you have an adjustable backstay tensioner to do this? If not you need to balance the rig tension by tightening either the backstay or foretstay bottle screws for an optimum performance.

Regards.

Peter.

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[Guest]

Vibrating leech when NOT severe is actually a sign of the air-flow coming off the sail an not a fault. If you think back to old 'trick' of blowing along a sheet of paper - you will vibrate / flap the free end as the air flows off. It si NOT a sign of badly trimmed leech / sail. For that study the tell-tales.

Tightening a leech line is a common mistake and leds to 'hooked' edge and a significant loss of sail power from that flow. I in fact slack off the leech line as much as possible and observe the tell-tales that stream off my leech to trim / set the sail. If they are straight and flying in line with the leech as an extension - you have the sail and leech set well. Have all tell-tales on and at edge of sail horizontal and along the sail ... both sides and the sail is 'on-spec' !!!!

Enjoy the sailing, take in a little bit of leech line to reduce the chatter - don't overdo it, or better still sew on some tell-tale tapes about a foot long at intervals up the sail..... in really contrasting colour ....

Good luck




<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I only came - cos they said there was FREE Guinness !

 

[ex-Gladys]

After a lifetime sailing dinghies and cats, a drumming jib is only due to one of two things; the fairlead is too far off or the leech on the jib is stretched and knackered. Tightening the Leech line as stated earlier is not a solution, the leech can be re-cut, but a new jib is the real solution.


Larry

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