On Jan 31, 5:41 pm, RichH wrote:
... The above will work as a close approximation ... at least that was the
method of most designers that Ive asked this direct question ...

Yeah, there seems to be a lot of rules of thumb and hand waving on
this. I'm certainly no expert. The only rig design I've paid for was
done using some magic and proprietary computer code. But, since the
OP wanted to know how much strain he was looking at and he already has
the rig, wouldn't it be easiest to go look up the wire's specs from
the provider and then make up a strain gage that could be read while
under sail? I think a clever person with a meter stick, some tape and
a sharpie might be able to get pretty good figures. Maybe a good
Loose gage would be adequate if looking for a store bough option.

But if you really want to work it out theres this... Oh, forget
it...

-- Tom.