Author Topic: 2:1 main halyard  (Read 2272 times)

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Offline Bruce

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2:1 main halyard
« on: May 04, 2011, 16:15:13 PM »
Was speaking with someone last week who says he is thinking of installing this, primarily to reduce mast compression.
I haven't ever noticed a 2:1 halyard on a mini.  Any thoughts?

Offline NicoG

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Re: 2:1 main halyard
« Reply #1 on: May 04, 2011, 23:17:35 PM »
to much rope for me.

Offline ctut

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Re: 2:1 main halyard
« Reply #2 on: May 05, 2011, 04:50:34 AM »
My Nacira had one from the factory, I think a few of the P2 guys have done this too.

Offline Bruce

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Re: 2:1 main halyard
« Reply #3 on: May 05, 2011, 10:31:16 AM »
Seems like too much rope for me, too, but would reduce mast compression and the load on the clutch.  What did you think of yours, Chris?

Offline NicoG

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Re: 2:1 main halyard
« Reply #4 on: May 05, 2011, 23:56:27 PM »
The mnini rules for series specify the mast weight, and hundreds of mast with 1:1 have sailed safely, so for series this is not really needed.

And for protos, I do not know if the lesser load can be used to design a lighter mast, as the halyard load is not hte only one on the mast. Maybe Chris knows more on this ?

Offline Kevin

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Re: 2:1 main halyard
« Reply #5 on: May 06, 2011, 11:02:32 AM »
Surely there would not be any reduction in mast compression, the same tension is applied between the head sail at the top of the mast and the tack at the gooseneck.

I have a 2:1 main halyard, mainly because it was already on the boat when I bought it.

Advantages -
Easier to pull up, especially if there is a lot of friction in the main track
Easier to tension if you have small or no halyard winches
Thinner rope so marginally less weight aloft when the sail is hoisted, probably insignificant.

Disadvantages -
Loads and Loads of rope in the halyard bag when the main is up.
Twice as much halyard to tangle up when you're dropping the main in a hurry.

There is no significant reason either way.

Kevin.

Offline NicoG

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Re: 2:1 main halyard
« Reply #6 on: May 06, 2011, 17:16:44 PM »
THere is a load reduction, but maybe youre right, its not in mast compression but in load in the halyard.
But still wondering, come on experts :) You change the load to the attachement of the halyard and the block, instead of only over the block. Will this make it easier/more durable for the construction in carbon ? Heard of a few occasions of trouble up there with this.

Advantages,
easier to pull up,
a mini sail should be hoisted very eaasy, otherwhise you need to clean the groove or check your luff cloth. One trick is to ease youre runners to straighten the mast a bit.
But still an advantage.

Easier tension:
never a problem for me. except in strong winds I kept the halyard on the winch and clutch.
But that is for creep and slipage.

Disadvantages,
yep the spaghetti.
ONe trick here for newbies, drop your tail, the whole shit, in the water over the stanchions,
this uncoils it, keeps it straight to the clutch and gives some friction, specially handy for spinnakers.



Offline ctut

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Re: 2:1 main halyard
« Reply #7 on: May 07, 2011, 20:20:06 PM »
I liked it, never felt the extra line was a burden.

It does save a bit of weight up the rig since the halyard was 6mm versus 8mm. Not a huge saving but some. When the sail is up the amount of extra line in the mast was just the small bit of 2:1 at the top of the mast. It does require using a halyard shackle so a small weight penalty there versus tying the halyard to the main.

I never had any issues with the halyard moving, it was a pretty solid across the wind range. Also the halyard tension varies less as the mast bends and straightens from the runners and checkstays.

Knowing there was less load on the clutch was nice. I never needed to keep the main on the winch which meant the headsail or spi halyard could stay on the winch, never in the 2009 season did I have halyard damage from a clutch

As for compression, there was less compression load on the mast from the halyard versus a 1:1 but the sail load remained the same on the spar, lighter blocks and smaller sheaves can be used too for additional weight savings.

100% agree about tossing lines out the back to drop sails, removes any tangles and adds just enough friction. Spi tackline too.

Offline NicoG

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Re: 2:1 main halyard
« Reply #8 on: May 09, 2011, 17:04:36 PM »
Thanks Chris,

still thinking about the compression load, if I think Euler methode, no compression loss.
But heard about halyard locks decreasing compression load...
Still not clear to me :)

Do think though that the loads of the mainsail get transferred by the luff, headboard, tack. Not through the halyard. At least that is normally how you design a mast for amateur designers...
On the halyard you put the tension in, maybe  the tension increases in gusts, but not big time.

FYI, the Zero I specced in race layout had 6 mm dyneema halyards, and two cabintop winches (pure luxury :) )

Offline ctut

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Re: 2:1 main halyard
« Reply #9 on: May 09, 2011, 17:51:04 PM »
I think some of the compression differences have to do with the sail loads being slightly aft (towards the end of the boom) while the halyard loads are vertical.


Offline NicoG

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Re: 2:1 main halyard
« Reply #10 on: May 09, 2011, 23:48:48 PM »
Yep, dived into this.

there is a load in the halyard, but this is not big, and as Ctut says partly due to  loads being aft.
So an halyard lock saves a bit in compression loads, but not as big as I thought due to marketing skills of the makers of them :)


Qute Karver:   Less compression in the mast since no more halyard load. All the force on the luff going directly in reducing luff sag and not holding the sail.

But for a serie mini this is not relevant as the section is designed for RM at 30 degrees and then with a safety margin added to it. The load of the halyard is so small in comparison to that number, I would not think about it anymore .... (only talking about compression load as argument, not ease of handling etc)

Thanks to the French designer Gutelle, which great design books are not really known outside France, and in Volume 2 he goes into the forces in the sails and rigging. SOmething no other design book I have talks about. Its outdated, Volume 2 only in French, but google found one chapter in English...
http://www.boatdesign.net/forums/attachments/sailboats/2164d1103169762-sail-loading-rig-rig-loading-vessel-french-mast-vi-i.pdf