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How a 2:1 halyard works


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Sounds like a job for Myth Busters!

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I'm not talking about halyard layouts anymore, HOWEVER

 

I learned yesterday that North 3DI sails offer greater mast (fwd/aft bend) support than any other sail construction method. Because they have 90° fibres across the sail offering fwd/aft rig support. So your rig will bend slightly less with 3DI

 

Draw us a picture of how that works Josh…… 8)

 

If I wasn't so busy doing work for you WT I could have shown you that AGES ago.

 

jk

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oh god here we go again.......

Really IB do we have to explain the 2:1 halyard thing yet again or can you just go back a few pages?

 

Boo yes please explain your theory again

 

If you put a set of scales under the mast and throw 1:1 - 2:1 - 20:1 or even 100:1 purchase on a halyard, the load (compression) on that set of scales cannot decrease.

Youre saying that load (weight) read on those scales will get lighter the more purchase you put on the halyard ??? - Maybe the stays are there to hold the whole shootin match from liftimg off

 

Tell me if Im wrong

 

D.

 

PS . San Fran was a blast, a pretty cool city

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actually it does reduce the compression load induced by the halyard. but of course never by more than the halyard tension . of course the real issue is that BC a standard 1:1 halyard puts twice the halyard tension into the mast! motorbikes diagram on the previous page explains it perfectly.... review that if this is difficult to follow. other diagrams further back do the same. :D

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if the halyard is terminated at the masthead, without going around a sheave, then the total mast compression induced by the halyard is equal to the halyard tension. this compression is carried in the mast from the gooseneck to the halyard termination at the masthead.

 

if the halyard goes up and around a sheeve, then the compression is twice the halyard load, unless it is a 2:1 halyard....

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Sorry Booboo, but you and several of you are quite wrong on this. You do not reduce the mast compression no matter how many purchases you have. The Mast compression comes from the tension you have in the luff of the sail plus the weight of the Sail material itself.

Lets say that total load is 100Kg. 1:1 will see 100Kg on the halyard also. But that does NOT Sum to make 200Kg of mast compression. It is 100Kg @ 1:1 = 100Kg on both sides.

2:1 simply makes the Halyard tail "see" 50% of the 100Kg. But the Sail side of the halyard never changes. The sail and the halyard still exerts 100Kg from the top of the mast sheeve to the foot of the sail where ever the point of connection of the bottom of the sail is. eg, the Gooseneck.

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