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Discussion Starter · #1 ·
The backstay on my boat is the "inverted Y" type of backstay with a 6 to 1 block and tackle on one leg of the Y (giving what I think is an approximate 12 to 1 mechanical advantage overall). The rig is a 9/10 fractional rig with only one lower shroud (each side), with swept back spreaders and a roller furling genoa. The wire sizes are 7/16" for the backstay, and 1/2" for the shrouds (lower and cap) and 5/16" for the intermediates (total of 2 spreaders). It is a production cruiser type of boat (sloop rig). I can't seem to find a loos guage for determining tension that will accept wire this thick?

The information from Selden on this rig, is that the backstay should not be tensioned more than 20% of it's breaking strength (at any time), and that it should never be allowed to completely slacken.

My questions are:
How do I tell what level of adjustment to use? When do I use the full 20% tension and how do I tell when I am there? For downwind, how much do I "let it off"? In light wind, how much do I let it off?
For example to loosen for downwind, do I let 3" of line through the 6 to 1, or ??? from the fully tensioned position?
Up to now, I have avoided using the backstay adjustor, probably because I am unsure of how to set it properly. I am not even sure how to tell when it is tensioned to the 20% of breaking strength point.
Thanks in advance for your advise and help in "demystifying" this control,
Tom
 

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Discussion Starter · #7 ·
Summarizing and Thanks

OK. So if I understand the general consensus so far, I need to mark the backstay tensioning line at a location just before the system is slack (and maybe even tie a stopper knot in the line to ensure it cannot go totally slack), and also mark the line where the tension is "fully on" (at 20% breaking strength), and then experiment under various points of sail and wind conditions to see what works best (and when). The best method I have found so far to determine the 20% tension point is using the folding rule method described in the Selden mast book, attaching a 2 meter stick to the stay using tape and measuring the distance between the stay end and the stick. When the wire has stretched 1mm (the slack distance has increased ) that would equal 5% of breaking strength.
Sailing Dog, I like Alex's videos alot. They do give a good idea of what to do and why.
Thanks for the responses, this site is great! If anyone disagrees with my summary or wants to add some additional advise, please do.
Thanks again,
Tom:)
 
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