The pattern was cut and fitted together with tongues and grooves. OnBce it was checked "dry" in place. Then the sections were epoxied togehter off the boat. The whole assembly was then put in place and bedded epoxy. Four screws per panel were drilled in to hold it in place on the cockpit floor. After it set, the four screws were backed-out, the holes in the fiberglass were filled with expoxy and plugs put in on the surface. We then used a rubber-like caulking to fished the joints. That could have be omitted but I think it increases the resistance slipping and has the old "plank" look.
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By doing this i) the whole assembly functions together, ii) you have fewer leaks below to freeze thaw, mildew, etc. and iii) by keeping have very minimal; and iii) repaired holes that were just to hold the piece in place during the time for the epoxy to set-up and cure.