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Re: Backstay adjuster mod.
[Re: Cap'n Vic]
#10375
10/19/10 01:22 AM
10/19/10 01:22 AM
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Joined: Mar 2010
Posts: 93 PNW
lakesailor
Senior Member
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Senior Member
Joined: Mar 2010
Posts: 93
PNW
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The ability to depower or flatten the main via backstay may have been a bit over-optimistic concept. but then the original traveller track was choked. This was designs from 30 years ago. 16 true may have been one of those edge points for moving into a #2 which was a required sail 30 years ago. Some of us like the #2 a lot over 15. I think it is perhaps a 145+?
Flattening the main was not a problem, mostly I would have liked more backstay to help reduce the headstay sag as we were definitely at the top end of the #1. The upside is that the J/30 is a Freightliner uphill in those conditions_.
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Re: Backstay adjuster mod.
[Re: jhoskins]
#10376
10/19/10 01:24 AM
10/19/10 01:24 AM
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Joined: Mar 2010
Posts: 93 PNW
lakesailor
Senior Member
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Senior Member
Joined: Mar 2010
Posts: 93
PNW
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A "balanced" rudder helps with the arm workout and dump truck feel. A balanced rudder would help, no question about that. Unfortunately in our PHRF region rudder modifications get hit fairly aggressively.
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Re: Backstay adjuster mod.
[Re: Cap'n Vic]
#10381
10/19/10 12:58 PM
10/19/10 12:58 PM
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Joined: Sep 2000
Posts: 393 Rockwood, MI, USA
Russ Atkinson
Senior Member
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Senior Member
Joined: Sep 2000
Posts: 393
Rockwood, MI, USA
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Headstay sag is a function of its length, diameter of the wire and tention. Shortening the headstay an inch or two won't much affect head stay tention but, as Bill points out, move the mast forward - which will move the CoE to help balance. On the J/30, backstay tention will only marginally help headstay sag as most of the force of tentioning goes toward bending the mast. Some have even argued that bending the mast causes the center portion of the mast to move forward, thus inducing more headstay sag. My conclusion is that I don't get any noticable improvement in headstay sag from increased backstay tention.
As for depowering the main, backstay tention will flatten the top 1/3 of the sail and open up the leach. Enough backstay tention will actually invert the top of the main. The right compbination of traveller adjustment and backstay tention will go a long way toward balancing the helm. A de-powered main and a balanced helm are a lot faster than an overpowered J/30 and make it a lot more comfortable to drive. And as an FYI, while I can't speak to current Dacron sail design, the original Dacron mains came with a flattening reef about 6-8" up the leach. The old rule of thumb was for 16k of wind and above - strap in the flattening reef. The flattening reef pretty much took care of the bottom of the sail - the backstay took care of the top. A blade for a main, traveller down, full crew on the rail - the old mantra was "which number 1 are we putting up today?" (as in; the old blown out #1 or the new - let's save it for important races #1)
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Re: Backstay adjuster mod.
[Re: Cap'n Vic]
#10388
10/20/10 01:12 PM
10/20/10 01:12 PM
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Joined: Apr 2007
Posts: 493 Chicago, Il. USA
D. Bartley
Governor at Large
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Governor at Large
Joined: Apr 2007
Posts: 493
Chicago, Il. USA
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I oncet had a conversation with a guy named Baird... a pretty good J/24 sailor in his day. He pretty much confirmed what LakeSailor said... the lowers effect how stiff the mast is. If you have a stiff mast, then backstay does indeed effect headstay sag pretty dramatically.
When it's blowing here on Loch Mich, we'll crank on uppers, and lowers are about the same tension.
Dennis Bartley Planxty, s/n 23994 hull 205
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