The pieces don't really shrink or expand, they just curl open or closed. The preloading is probably not ideal, but it doesn't seem to cause any problems in the long run. Some sticks and tape to hold everything in place is a good idea.

: It sounds to me, from all the responses, that one needs to worry about the
: hull shrinking and being too small than the deck "stretching"
: and getting too big. Is this correct? What does all this preloading do to
: the structural integrity of the hull as a whole when you're forcing the
: halves together?

: I suppose I could make two sets of forms, like Nick... :-) Nah, too much like
: work!

: I like Ross' idea for prevention with the sticks - I'll be sure to remember
: that when I start my glassing. Seattle has some pretty drastic variations
: in humidity/temp from day to day, so I'd best be careful.

: Scott.