Need To Replace Sub-Floor, Anyone Done It?

[lester]

I have a '90 Dolphin that I picked up last spring. It had had some water damage, which I thought had all been taken care of, new paneling, fresh paint, fresh flooring, etc. This spring I noticed the floor in the bath is soft, the previous owners just laid down new flooring on top of a rotten sub-floor. We decided to go on a 4500k trip anyways. No problems really, but now it's time to replace. I'm going to have to remove the shower pan, toilet, vanity, and possibly the partition wall between the kitchen and bathroom to get at it. I'm fairly handy, but have never seen the guts of an R.V. floor.

BIG question is... will I be able to slide in some new plywood from the inside, or am I going to have to peel away some of the exterior, ie, cut away panels of fiberglass and then patch it up back together when I am finished?

Anyone done this before? Are there joists, or is it just plywood on top of the frame?

Sorry if this is in the wrong catagory, I'm a newbie.

[zero]

BIG question is... will I be able to slide in some new plywood from the inside, or am I going to have to peel away some of the exterior, ie, cut away panels of fiberglass and then patch it up back together when I am finished?

Anyone done this before? Are there joists, or is it just plywood on top of the frame?

Sorry if this is in the wrong catagory, I'm a newbie.

I've never had a Dolphin floor apart. Had several Chinook Minicruiser, and Winnebago floors apart though. All were pretty much the same . NO floor joists for sure. They all had a sandwich design. Plywood and foam laminated together and glued. It's the total package that makes the strength. Some have wafer-board for rigidity like the Chinooks. Looks like cardboard honeycomb. What takes the place of floor joists are usually 1" X 2" or 1" X 3" wood strips. 1" nominal thickness and 3/4" actual. One bathroom I did - I cut everything out that was rotted. Then scabbed in new 1" strips. then laminated a new floor with 1/4" marine plywood and 3/8" marine plywood and glue. Much depends on what you find when you tear into it. Just remember you want the most strength you can get for the thin plywood used. Run-of-the-mill pine plywood from Home Depot or Lowes is too weak. You need something with as many plies as possible - with exterior glue - and hardwood or douglas-fir.