whats best way to do it?? plywood floor to fiberglass stringers,,,

I'm not sure if I did it the best method but when I did my floor I didnt use any fasteners. I didnt want to penetrate the fiberglass with any screws in an effort to keep the stringers dry. I "glued" down the stringers with the thickened resin and then when I did the center section over the fuel tank I filled the void again with thickened resin and then covered the entire floor in CSM and a woven glass fabric. I was worried about the floor lifting and separating from the stringers but after a season it still seems good to go!

Cut some strips of cloth to lay on the tops of the stringers. Wet the stringers then the cloth and the area on the back of the floor where it will hit the stringer. Assemble without sliding around and put a bunch of weight on top. Let dry.

You could also glass some 2x2 along side the top of the stringer and use some stainless screws dipped into 5200 to hold the deck down.

What kind of boat? Did you put in new stringers or just replace the floor? Can you post a picture?

There are many different ways to accomplish the same thing. I added ribs between my stringers that I screwed the floor into. Before I did that, I put thickened resin on top of all my stringers and ribs prior to putting the floor in place. The screws were to just hold the floor down until it cured, but I used the ribs and not the stringers as I did not want any penetration at all into my new stringers.

stringers where good fiberglass with foam filling.. old floor (plywood) seemed like it was glued with somethingn like 5200?

first pre fit the wood your using,,then you will need to apply a sheet of 1708 fiberglass to the bottom side of the wood to keep it from rotting from the bottom up..let it cure..sand the areas you are going to be bonding to the stringers. also take some acitone to the areas to make sure all the wax is removed so the core bond will stick to it,,mix up some core bond and aply it to the top of the stringers,,hopefully uou have access to under the floor so you can add some tabbing,if not then you will have to predrill some holes to fasen the floor to the top of the stringers..after everything cures lay 1 or 2 more pieces of 1708 on top of the wood and let it cure,,again sand and wipe acitone over the floor to remove the wax co the carpet glue will stick.... ..

Can't I just coat the ply with resin on bottom??

you can even apply some mat to the bottom if you want,,just need a extra barrior their to keep the water out..i dont believe in just resin unless you give it several coats post cureing between coats..

I like corebond as well but its hard to find in small amounts like gallons, I can only find fives but I go through tons anyways

in a pinch west systems 404 and ve resin makes a tenacious bond to