Are these floor boards actually wood? What's the vintage of this boat? About 10-15 years ago, there was a switch from Real Plywood to some sort of composite for dingy parts (floor boards, seats, transoms. In my opinion, this switch was for the better - the new material doesn't delaminate and requires little or no maintenance. It's kinda like Trex decking - why fight with wood?
If these floor boards are actually plywood, the first thing I'd do is see if replacements are available in the composite material - end of problem. If you're into restoring old plywood boards, there are a few steps to take. First is to let them dry out - can't work with soggy wood. Second is to correct the delamination - separate the plies a bit with a putty knife and let epoxy seep into the gap (helps to thin it a bit with xylol). Clamp and let cure. You'll likely do one edge at a time, rotate 90 and do the next edge. At this point, you have functional floor boards that need preserving for the future.
I'd fill any spaces or gaps with an epoxy filler (mix your own) then coat with glass/epoxy. You don't need a heavy layer - use the thinnest glass you're comfortable with (and can obtain cheaply). I recently did a waterproofing job with 1.5 oz glass per the customer's request, but it ran up the cost and was tough stuff to handle - like silk. Once this cures, wash with soap & water then paint - for color and UV protection of the epoxy.