On Thu, 31 Jan 2008 20:33:11 -0800 (PST), "
wrote:

...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. ...
-- Tom.

A meter stick to measure strain is perhaps not the best way, but the
suggestion has merit.
The pro approach to stress testing involves strain gages. They need a
little smooth patch of structure less than a square inch to glue to.
That's a difficulty for rigging, sure enough.
But a thin aluminum strip, 3 or 4 inches long, strapped securely to
the rigging, with the strain gage measuring the stretch of the strip
which is transmitted from the wire would do the job perfectly well.
Low noise amps, data acquisition PC and you're in business.

Brian Whatcott Altus OK