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2:1 halyard hardware


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No, the compressive load on the rig is taken by the mast structure, between the mast top sheave, the tack fitting and the mast crane termination. If your halyard is fastened on the mast somewhere, then NO compressive load from the halyard is transmitted to the step. Think about this, if the rig is out of the boat,  and you fasten the halyard to a cleat on the mast, can you still tension the sail?? Of course you can, but there is no step!

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Dont think thats right?  Bit worried to have a go at this, but in the 1:1 case, the sail applies a 50kg load down, the halyard the same vaule to hold it up there, therefore masthead has 100kg of

Our Vote would be Tylaska we currently have the non sheave version. Never had an issue with it.

So i've done a couple of sketches and they show in a 1:1 setup with 50 kg (technically should be called 500 newtons) of force holding the sail in position there is 50 kg of "pull" in the halyard going

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On 25/04/2020 at 11:51 AM, Clipper said:

Dont think thats right? 

Bit worried to have a go at this, but in the 1:1 case, the sail applies a 50kg load down, the halyard the same vaule to hold it up there, therefore masthead has 100kg of compression.

In the 2:1 case, the load required in the halyard becomes 25kg each side of the main, and another 25kg tension, so maybe 75kg compression?

Im ssure ScottiE or Ed will correct me if Im wrong.

Missed this sorry Clipper - yes you are correct - back yourself mate.  As well as lowering mast compression, it also halves the load needed for the halyad size - weight aloft.  Not so critical for halyard itself but good for those guuchi masthead halyard locks - ie. the load to release it is half!

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2 hours ago, Adrianp said:

On freedom we had a low friction rig with a wide stainless steel shackle over it. It meant the pin of the shackle was very close to the top of the main and halyard. Simple and cheap!

A home made version of this? https://marine.wichard.com/rubrique-Captive_pin-0201110100000000-ME.html

Any photo?

/Martin

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So I'm still thinking........ so many scenarios...Main halyard comes down  to block on mast collar then back to clutch aft. Say 50 kg.  So upwards lift on mast collar 50 kg ? Surely that transfers back up mast thence to mast step ?  Or am I overthinking / over complicating. BTW I wasn't good at Physics !

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There ya go, a nice work out for the grey matter to fill in some jail time.

I went to whip up a quick test rig last evening to show it all more graphically but the neighbour threw a bottle of gin at me and things went a little wobbly but we got this wee Hmmmm... thingy sorted.

Mast set up with cell in the middle.

no load.jpg

All loads zeroed out so any change is due to what we do.

1 no screen.jpg

Set up 1:1 with a 5.2kg weight added simulating a sail

1 2 to 1.jpg

The load showing with 1:1

1 2 screen.jpg

The set up changed to 2:1, same load

1 to 1.jpg

The load is now

1 1 screen.jpg

Checking the load

1 the weight.jpga

So changing from 1:1 to 2:1 saw the load change from 10.28kg down to 7.47kg which is around 25% reduction.

Lots of Bombay Sapphire East was harmed in the pissing around with that jig. With ginger ale, lime and lemongrass, pretty damn morish.

 

14 hours ago, Adrianp said:

On freedom we had a low friction rig with a wide stainless steel shackle over it. It meant the pin of the shackle was very close to the top of the main and halyard. Simple and cheap!

Concur, easy as, cheap as, do the same myself.

There are other fitting options equally as good, some would argue better, than the usual 2 or 3 go to's in NZ and all tend to be far better value for money.

1 no load.jpg

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