"Spongy" Floor

[zbishka]

Hey All,
I have an 18' 86 Fibreglass SportCraft (Stern Drive) Boat. The floor has an aproximate 3' x 3' area just above the gas tank that is really spongy and I'd like to replace it before any further damage happens. I contacted Sport Craft to see if they could furnish me with a "Blueprint" of the flooring for this boat and I was informed that they no longer make this boat. I'd like some kind of illustration before I cut into the floor for replacing it. My concern is where are the "Joists", How far apart are they 16 On Center, etc, how thick is the wood?
Another question is Would it make a difference if I used Pressure Treated Plywood as opposed to Marine Grade Plywood?
Please advise me if you can. Can you please let me know if there is a floor plan available for my boat I can purchase? And once again thank you in advance. Mark

 

[Teamster]

Re: "Spongy" Floor

My guess is that if the floor is "spongy" that you may well have rotten stringers as well,.......

 

[TruckDrivingFool]

Re: "Spongy" Floor

Welcome to iboats dry dock!

There's no real standard on spacing/layout for your stringers ("joists"). It's basically a tear it apart and see what's there.

To dovetail onto what Teamster said, since boats tend to rot from the bottom up usually once you have rot in the deck there are more issues underneath. Once again you'll have to tear into it and see what you're working with.

You can use PT but it will need to be dried quite a bit before you'll be able to get fiberglass resin to stick to it. There has been much discussion on the subject of what wood to use a search will yield plenty of reading for food for thought.

Finally, once you tear into it post pics (we love pics) and ask questions where you need to. All the great people here can help you through anything.

 

[Cadwelder]

Re: "Spongy" Floor

Yep to all the above, rip her open and see what's underneath, I'm sure you won't be please....

And a stringer layout isn't needed anyway, you'll be able to tell once you get the deck out of the way....

CW

 

[zbishka]

Re: "Spongy" Floor

Thank you to ALL that gave their advise. I do appreciate it. I'll have to rip it open and see what's what. You guys are "priceless" Zbishka