Running backstay specifics

[mholmes]

I am planning on using amsteel (5/16" good?) to a block on the rail to the primary winches, as I have read recommended previously on the forum.

Can I use any standard block or do I need something seriously strong? Is there some reason why everybody always recommends a snatch block when it seems to me that a standard block does the same thing for a third the price? Same thing with the padeye? What loads are we talking about here?

and the most tricky question: how do I know how far back to locate it along the rail?

much thanks,
matt

[Brian Duff]

it wil help if you state the boat and rig with each post regarding the sizes or loads on a rigging component.

size has everything to do with it

[mholmes]

of course, my mistake!
Valiant 40, a cutter rig originally built with aft-led intermediates
regards,
matt

[Brion Toss]

Hi there,
Okay, we know the boat. The ideal location for the blocks will be about as far aft as the forestay is forward of the mast, though this will almost invariably be modified by issues of deck traffic, the location of other fittings, proximity to house sides, etc. I'll check my files for Valiant 40's,and see if we recorded a length.
As far as the block goes, I definitely agree that a snatch block is a bad idea; you'll essentially be putting standing rig loads on this block, and its escape vector aims it at your head when you are in the cockpit, so you want something simple and stout. Not sure what the best choice for this job will be; the load on the block will probably be about the same as the load on the line, and you want a generous safety factor.
To get meaningful hardware you need to know the loads on everything, as well as the assorted safety factors.
Fair leads,
Brion Toss

[Brian Duff]

perhaps you best bet is to either get a copy of the rigger apprentice and study up, or to call Brions shop for consultation.

on most boats that size we use the harken large round padeye, and harkens 75mm ESP fiddle and fiddlebecket cam blocks with 7/16" sta set line, and the runner of 5/16" dyneema- covered. that is of course when the folks want the block and tackle kinda runner.

the other option is a runner of 5/16" dyneema to a single block, then a control of 3/8" dyneema that deadends on the rail, goes through the blcok on the runner and then through a block on the deck and to a clutch then winch. Use either Karvers blocks for this setup, or harken blackmagic hiload straphead blocks.
you might get lighter weigh hardward , but somebody needs to run the math to determine if that is all correct.


I thought the old runner rule was 1/2 way from the mast to the rudder post....