hi...welcome to iboats.
after the under side of the deck is fiberglassed.....it is pre fitted to the shape of the boat......sitting directly on the stringers and what ever support frames you have installed.
(have a look at the link in my sig...there are detailed pics there)
after the fitting.....and everything is all hunky dory....chalk line the stringers and frames on your new deck.
pre drill a few main holes thru the deck into the stringers or frames.....(this will stop the deck from moving while installing it.)
remove the deck.......either pl it down by pl-ing the top of the stringers...
or add wet fiberglass csm strips on top of the stringers and then lay down the deck a board at a time and screw it down in the pre drilled holes
keep adding deck sections till done....
then use standard deck replacement methods....like drilling all the holes....adding sealant...then adding the screw...and glassing in the deck.
cheers
oops