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Best rope for main halyard

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Peaky View Drop Down
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Post Options Post Options   Quote Peaky Quote  Post ReplyReply Direct Link To This Post Posted: 19 Mar 09 at 3:41pm

James, what is mast foot pressure a la windsurfers?
At any rate, you can't have it both ways - if the 2:1 system is pulled right to the top, there is virtually no extra length of halyard able to stretch/creep.  If the 2:1 isn't right at the top, then the angle between the ropes is going to be nearly 180 degrees, and therefore the 2:1 will work efficiently.  And what ever extra length of halyard there is, is in parallel, not series, so the stiffness is increased (hence less stretch).

Paul, sorry to say Chewy and me are one and the same - I lost my login details!  Tempted to do the Thornbury regatta though.



Edited by Peaky
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craiggo View Drop Down
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Post Options Post Options   Quote craiggo Quote  Post ReplyReply Direct Link To This Post Posted: 19 Mar 09 at 10:40pm
Aaahhh it all becomes clear now. The mysterious Peaky is in fact Chewy!

Jimbo when I was in the 600 fleet the main reason for going to 2:1 other than peer pressure was a belief that you could use the mechanical advantage to ensure that you had enough tension in the halyard to hold the head of the main at the top of the mast even with yehaaa cunningham applied. In my opinion it didnt work, as you regularly saw mainsail heads 6" below the mast tip even with 2:1. I firmly believe that this is down to the loss of mechanical advantage as you go block to block at the top. Once creep and stetch set in you actually end up with more rope to stretch and creep thanks to the 2:1 and so the sail appears to drop lower.

Best way to rig the 600 was always to make a crude 3:1 purchase with the tail at the bottom of the mast and pull on a load of tension. Even with extreme cunningham you get only a small drop in mainsail.



Edited by craiggo
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Paramedic View Drop Down
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Post Options Post Options   Quote Paramedic Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 09 at 7:25am

A well known mast maker tested this out with weights. The results were astonishing in that the halyard running inside the mast operated under a mechanical disadvantage from kicker, cunningham and mainsheet loads so the the rope in the mast actually holds twice the load of the luff on the sail. If you think about how you rig up a cunningham this does make sense.

In some classes you want this to help de power, but in merlins with the flexible carbon spars the "bow and arrow" effect should cause a power drop just when you want it least, ie force 2 or 3. Halyard locks are becoming popular again, but I opted for a 2:1 halyard but haven't really sailed enough since to draw any conclusions. It looks good on paper though.



Edited by Paramedic
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BBSCFaithfull View Drop Down
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Post Options Post Options   Quote BBSCFaithfull Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 09 at 9:27pm
I have a release mechanism in my mast so no worried rib drivers
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Medway Maniac View Drop Down
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Post Options Post Options   Quote Medway Maniac Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 09 at 11:05pm

Originally posted by BBSCFaithfull

I have a release mechanism in my mast so no worried rib drivers

Sounds interesting. How does that work?

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Post Options Post Options   Quote BBSCFaithfull Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 09 at 4:35pm
It comes from cst. Its basically a pin attached to a rope on the bottom of it.

Through which the head of the sail is attached

http://www.cstcomposites.com/images/Dinghy%20Mast%20head%20Q .Release.JPG

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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 09 at 5:43pm
Originally posted by Medway Maniac

You can explain that to the next RIB driver who rescues you

If I were on the safety boat I'd be delighted to see it. No wire halyards, no expensive ropes, just 5p worth of string I can unhook or cut with a knife and the sail comes down immediately with no snagging of rope in the cockpit.

Edited by JimC
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