"The Captain...cap n all" wrote:

How big was this thing Doug?

It was a Frers designed 1-Tonner, maybe 38' or 39' LOA


Most boats assume a slightly different shape in water as opposed to
land only because they are suppored better.

Sure, but then relatively few boats are built to be as rigid as high-end
custom racers. At one point from the late 1970s through maybe the late
1980s it was fairly common to have a geodesic grid of aluminum struts
inside, completely obstructing the cabin. What a PITA.



I can't see anyone measuring 4 thou in a live environment and assuming
accuracy to that level.

Well, to be honest I don't know how the boatbuilder measured this. It's
not a matter requiring scientific accuracy, but there are several ways you
could measure it with an independent frame or taut wire. Nowadays you
could set up a laser deflection meter easily and quickly.


....distortion measured on the newest IACC boats but
the early 1990s boats had very high rig loads (10K kg and up)
and very little (if any) distortion.

They bent.

Shucks, some of them broke! But I meant the hull deflection along major
axis from the rig loads. I suspect that they bent very little (a couple
millimeters or less), or that the hull deflection was designed in as a
tuning feature.... "some chop coming up, let's get the boat a little more
banana-shaped...."

Some of the production boats I've sailed bend visibly, several inches,
when the backstay is on and the rig loaded up.

Fresh Breezes- Doug King