Fiber glassing a new floor questions?

[JRO_1399]

I recently picked up a 1995 Nitro 185 Sport for a winter project. The floor from the consoles back was rotted. I cut out the rot and have cut plywood to shape. Now the questions begin... I have a small gap (3/8") between the plywood and the remaining floor. Should I use a filler to fill in the gap before fiber glassing the plywood to the remaining floor? If so what kind of filler? Is there a real difference in the quality of fiberglass and resins? Or can I get the generic stuff at my local Walmart? Do I need to use matting on the underside of the plywood or is resin alone sufficient? How many layers of matting is recommended to bond the plywood to the remaining floor? Do I need to use matting on the entire topside or just the joints between the plywood and remaining floor? The area will be covered in carpet so not concerned with looks. Sorry for all the questions but internet searching has just made me more confused ...

[Ray_Hubbard]

Use Marinetex to fill the gap and once dried you can glass over it.

[big_o_tom]

I restored a 1978 monarch in 1990. I used regular 3/4" plywood for the floor and transom. I used fiberglass cloth and mat with resin from an auto parts store. On the floor I used a 2-3" strip on the seam then when it dried I hit it with a wire then put a 4-5" strip over it. I just used resin on the flat surface of the plywood. I fished out of that boat for 15 years before getting a newer one. Then it sat outside the garage for about 10 years uncovered.
The one thing i can tell you is 25 years later the floor area was solid as the day i built it. 2 strips of glass on the seams and fiberglass resin everywhere else. Then carpet glue and carpet.
Under the back deck was a different story. The resin on the flat plywood had no carpet glue to keep it from cracking and therefore let water seep in. I cant say whether you need matting on the underside, I didn't use it and my floor was good for 25 years.