Your theory might have merit except for a few details:

First of all, the pictures are of my boat, while the problem was different boat, a Prout
37. The Prout has a third, central hull, called a "nacelle," and it is impractical to
support like mine. It is sitting on its keels. At first, I wondered if the center of the
Prout had sagged and should be supported, but we concluded that in fact the center had
risen when the weight and stress of the mast had been removed.

My boat is supported according to the factory specs. Although the keels can support the
hull for a limited period, they are not intended to support the hull for extended periods.
Since the three timbers are directly un the three bulkheads, the hull is support with no
flexing.



"Simple Simon" wrote in message
...
I see the problem. Those jack stands blocking up the
bridge deck are doing just the opposite of what that
area of the boat is supposed to do. If the stands are
taking too much weight the hulls are sort of hanging
from the bridge deck. In the water the hulls support
the bridge deck.

In the water viewed from the front the bridge deck
would have a tendency to be curved down a little in
the center portions. Jacked up as it shows the bridge
deck would be curved the opposite way. This would
warp the house in an abnormal manner.

S.Simon


"Jeff Morris" wrote in message
news
Its a catamaran - it can rest on its two keels. Prouts can be stashed like that
because
the keels are solid.

My keels, however, are "sacrificial" so its best to jack under the bridge, supporting
most
of the weight under the bulkheads:

http://www.sv-loki.com/Along_the_Way/UnderBelly.jpg



"Simple Simon" wrote in message
...
Check the jack stands. Some fool probably has the ones in the
middle way too tight and doing most of the work and bending
the boat in the process.

S.Simon


"Jeff Morris" wrote in message
...
I had a odd experience yesterday. I went to the boat to finish winterizing, and
saw
my
neighbor trying to get into his boat, a Prout 37 (which, BTW, has done 3
trans-Atlantic
crossings). The companionway door was latched and locked - he was baffled
because
the
door had never latched in his experience (he's had the boat a year and always
locked
with
an external padlock). After a while we were able to pry it open and figure out
what
had
happened.

On Thursday the mast had been pulled. This seems to have relaxed the hull enough
that
the
latch, which had not recently engaged, now caught the latch plate. We estimate
maybe
1/16
inch of flexing.

Before you jump on the fact that a catamaran hull had a bit of flex, here's what
the
owner
said "I surprised there would be any flex at all - but my old C&C 37 flexed so
much
when
we unrigged her that it opened a deck leak."