On Sun, 2 Jul 2006 17:52:08 -0400, "Glenn Ashmore"
wrote:

I have a Lewmar
80mm double with a 4,000 lb SWL but the Harken calculator says I need a
block with a 7,000 lb SWL which costs $550!

Where do you say enough?

Having a mainsheet block blow up on you at some inopportune time is
very unpleasant. Sooner or later you will be hit with a surprise gust
that takes you over 30 to 40 kts with a full main. That is what you
need to size for in my opinion. Trying to corral a flailing boom with
a jerry rig AND get a reef in at the same time is a very dangerous
job. Another 99% certainty is an accidental jibe or two at some
point. They create huge shock loads on all of the hardware as you
well know.

Bottom line is that I would not cut things too close.

I have some concerns about leading the mainsheet forward to the mast
also, having tried that arrangement once and giving it up. There was
too much friction in the system because of the multiple blocks, and it
was difficult to ease the main out in light air. All of the big 45+
boats that I have sailed usually had a simple up and over lead from
the traveler to a 180 degree turning block on the boom, with a winch
on each side of the cockpit.