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Mast head lock

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winging it View Drop Down
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Post Options Post Options   Quote winging it Quote  Post ReplyReply Direct Link To This Post Topic: Mast head lock
    Posted: 14 Jan 13 at 6:44pm
I am tempted to do this on my contender.  The wire halyard is fraying and keeps jamming in the sheave at the top.  I know the sheave will need replacing anyway, but this sort of stuff is so much easier with a decent line and an external halyard.  Good or bad idea on this class of boat?  it's a carbon spar.

edited to say if yes what line would be best?


Edited by winging it - 14 Jan 13 at 6:45pm
the same, but different...

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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 13 at 5:41pm
more on the subject here: http://www.boatdesign.net/forums/boat-design/halyard-locks-reduce-mast-compression-5968.html
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 13 at 5:21pm
Originally posted by batman

but isnt this putting the rig under far compression that a main halyard would?


Which is why certain classes don't use jib halyards.

The compression puts extra bend in a mast. Provided that the mast stiffness is correct with the halyard loads this is not that much of an issue, but you should be able to use a lighter or more flexible section without halyard compression. I have an excessively bendy topmast on my IC for my current waistline, and putting a main halyard lock on made a very substantial difference to keeping the rig powered up.

If your rig is over bending then a halyard lock may help. If its already on the stiff side then a halyard lock will probaby make things worse!

Edited by JimC - 14 Jan 13 at 5:22pm
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maxibuddah View Drop Down
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Post Options Post Options   Quote maxibuddah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 13 at 4:33pm
No or very low stretch in the halyard as well.
Everything I say is my opinion, honest
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SoggyBadger View Drop Down
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Post Options Post Options   Quote SoggyBadger Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 13 at 4:01pm
It's not just compression. In the normal situation where the halyard is made fast at the base of the mast somewhere when the mast bends the distance head to heel reduces so the halyard slackens and the main comes down a bit.



Edited by SoggyBadger - 14 Jan 13 at 4:02pm
Best wishes from deep in the woods

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batman View Drop Down
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Post Options Post Options   Quote batman Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 13 at 3:06pm

Main halyard lock at the mast head. The main benefit I believe is that they take the compression out of the mast. I'm not an engineer- what practical benefits will I feel on a Fireball? Some sailors are swapping to them and I know 470s use them- but at a cost of around £80 and some fitting work is it worth it?

The jib halyard has a 2:1 at the top so the load on that is halved- but isnt this putting the rig under far compression that a main halyard would?
 
 
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