| Re: Jib and self tacking
[Re: cooper engineer]
#188348 08/18/09 02:02 PM 08/18/09 02:02 PM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
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Posts: 6,049 Sebring, Florida. | The older Nacra jibs were pretty big and would be too big for a self tacker unless you had them cut down so they could clear the mast when tacking.
The newer -self tacking- type jibs are cut much shorter on the foot and are trimmed much closer to the middle of the boat (to the end of the self tacker car track). The newer boats with self tackers have spinnakers so the spinnaker is doing the work going downwind, where as the older, non-spinnaker boats needed more jib for reaching and downwind work.
An original Nacra 6.0 (big jib) will still reach faster than any of the new spinnaker boats if the reach is too high for the spin, due to their much larger jib.
Blade F16 #777
| | | Re: Jib and self tacking
[Re: cooper engineer]
#188350 08/18/09 02:27 PM 08/18/09 02:27 PM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | What's the difference of cut between a jib with and without self tacking ?
Thanks What pete said, but simplified, the older non-self tacking jibs typically overlap slightly with the mainsail. The newer self-tacking jibs are shorter on the foot and don't overlap the mainsail so they can remain sheeted to the front beam and pass through the tack without hitting anything.
Jake Kohl | | | Re: Jib and self tacking
[Re: Jake]
#188352 08/18/09 02:36 PM 08/18/09 02:36 PM |
Joined: Jun 2001 Posts: 3,116 Annapolis, MD Mark Schneider
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Posts: 3,116 Annapolis, MD | Note added
If you don't want to loose the sail area after you shorten the foot and change the balance of the rig. ... you make the sail higher aspect by raising and lowering the hoist and tack respectively.
crac.sailregattas.com
| | | Re: Jib and self tacking
[Re: cooper engineer]
#188358 08/18/09 03:28 PM 08/18/09 03:28 PM |
Joined: Nov 2005 Posts: 1,203 uk TEAMVMG
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Posts: 1,203 uk | that sail will go on a self tacker ok.
Last edited by TEAMVMG; 08/18/09 03:28 PM.
Paul
teamvmg.weebly.com
| | | Re: Jib and self tacking
[Re: TEAMVMG]
#188359 08/18/09 03:40 PM 08/18/09 03:40 PM |
Joined: Jun 2001 Posts: 3,116 Annapolis, MD Mark Schneider
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Posts: 3,116 Annapolis, MD | a clew plate added to the sail by a sail maker will allow you to get the jib leach right depending on where you attach the jib shackle to the clew plate.
Last edited by Mark Schneider; 08/18/09 03:41 PM.
crac.sailregattas.com
| | | Re: Jib and self tacking
[Re: cooper engineer]
#188372 08/18/09 05:53 PM 08/18/09 05:53 PM |
Joined: Jun 2001 Posts: 425 Toledo, Ohio (western end of ... Mike Fahle
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Posts: 425 Toledo, Ohio (western end of ... | That depends on what you mean by "cut", but the quick answer is "None, necessarily".
However, the detailed answer is: Because the self tacking jib has to fit inside the triangle defined by the forestay and mast, it is typically smaller than jibs that are not self tackers. In order to max out the available size (which is commonly desired and attempted), it is usual to cut the leech longer and bring it as close to the block(s) on the self tacker track as possible. This means that the sheeting angle is almost directly up the leech when the sheet is pulled tight and it requires having the best trim angle accurately located in the design. On older boats that have ovelapping jibs, like the Hobie 18, the clew is cut higher, the sheeting angle is almost into the middle of the sail, and there is a track allowing for fore and aft adjustment for best trim to account for differences in how the sail was designed or cut and also for close reaching or for different trim in different wind speeds and/or wave conditions. The best you can do with a self tacker is very fine adjustments on the sheet. That is another difference - a 1/4" sheet adjustment on the self tacker is much more significant than the same amount on the old style jibs.
If you are making a sail, then the high loads on the leech of the self tacker requires either a stronger material on the leech panel, a cut that aligns the strength of the material more vertically along the leech, doubling the material on the leech panel, or some other considerations for the higher loads on the leech. It is not uncommon to see leech gutter on these jibs after they have been stressed beyond there design.
I hope that covers what you were wondering about.
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