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Upper Leech area of Jib Luffing...
Posted: Mon Jun 06, 2005 8:17 am
by ESPERANZA
I added some new sail tracks for my jib sail. I installed them as close to the toe rail as possible. They are about nine inches outside the factory tracks.
This weekend we took the boat out for a test. The jib sheets better, points higher, but the top four to six feet of the leech wants to talk to you all the time. I tried moving the cars forward but still can't get rid of it.
Any ideas?
Dik...
Posted: Mon Jun 06, 2005 10:29 am
by Catigale
Dik
I think this makes sense if I read your post correctly.
Putting the tracks on the outside of the hull gives you more sheet angle (with zero angle defined as parallel to water) so now the jib feels less force pulling it in towards centerline...if this loss of force isnt made up for the increased downward pull of the clew (since the fore-aft distance of the sheet to the clew is less, as the track is now a lot closer to the clew) then I think you will spill the job more.
The first place it lets go and luffs would be up top, away from the the clew
Posted: Mon Jun 06, 2005 10:50 am
by ESPERANZA
So if I move the jib car fully forward, I should be able to get more down force on the sail and quiet the leech? When I tried this, it started back winding the main towards the bottom. However, I think a little more vang for a flatter main my help with this?
Dik...
Posted: Mon Jun 06, 2005 8:32 pm
by Tom Spohn
OK, what was the problem with using the stock jib tracks? Are you using the stock jib?

Posted: Tue Jun 07, 2005 9:46 am
by ESPERANZA
Tom,
I added the extra sail tracks because last summer, when sailing in light air, when I sheeted the jib it would back wind the main. When I relaxed the jib sheet the top would luff...
Dik...
Posted: Tue Jun 07, 2005 5:05 pm
by Tom Spohn
I'm a believer in checking out the basics first. So:
1. Make sure the jib is tight on the forestay--ie. the luff is tight. If you are using a furler you will find just above the furling mechanism the ties that can be tightened to insure the luff of the jib is tight. On Macs just make the sail as tight as you can--without breaking anyting.
2. In light air try the stock tracks with the jib cars all the way forward. This should reduce twist and tighten the upper part of the sail. Let out the sheets till the luff of the whole sail is flapping (luffing) and pull it in just to the point where it stops. If your jib has telltales installed (highly recommended) look to see if the yarn on both sides of the sail are streaming back equally. If one side is jumping up or even pointing forward use the sheet to adjust the sail in the direction of the offending telltale. If you have telltales on the top, middle, and bottom of the jib you can see how the air is moving across the sail. By adjusting the sheet in conjunction with moving the jib cars you can get a pretty good setting with all telltales behaving. To a racer there is more to be done to insure perfection, but on our Macs this will be a good setting.
3. After getting the jib behaving,
then you can fine tune the main. Make sure the halyard and outhaul are tight with no wrinkles along the bottom or luff of the sail. Then use the traveller or vang to add or remove twist till the streamers are all pointing back. You should have one streamer on the leach at every batten. Once again move the sail in the direction of the offending streamer. Get the lower ones streaming first by adjusting the sheet, then add or remove vang or traveller to get the top of the sail into shape. On a light air day you can actually just grab the end of the boom and pull it down to see if more vang will help.
Try this and let us know how it went. Good sailing

Posted: Tue Jun 07, 2005 6:41 pm
by ESPERANZA
That sounds great Tom, thanks. I'll give it a try this weekend...
Dik...