Just finished gutting the floor on this 33Eliminator . Same old story..... ****ty installation , screw holes ...the floor was only Tabbed to the Tanks at the Outside!!! WTF ! No structural supports at all . Found both Pontoons FULL OF WATER , about 40 gallons a side give or take . Any way, want some opinions on replacement materials.
Should I use marine ply encapsulated, or some of the new coring materials ? The old core was some kind of resin coated paper core . Looks like we have to pull the tanks and replace the rotted plywood benches they sit on . So I can build some structure up from the stringer to support the floor on the sides . Damn I thought Eliminator did a better job than that. Pictures are coming .

expanded PVC board would be nice for flooring etc

I am a little confused. You pulled the floor up, which should have been plywood, what coring are you talking about? Eliminator uses balsa as coring, if it gets wet it eventually turn to mush...that may be what you are seeing. Definitely post the pics

not many production builders weren't really that good, spotty quality control at best. If you can find a supplier for Coosa or Space Age Synthetics you'd be good to go with an engineered panel half inch to three quarter in the twenty four to twenty six pound range although you can go lighter as long as you make up for it in the encapsulating laminate (which is what typically i do). I use Thermo Lite Versatile for most stuff and vary density according to what i am building, mid to low twenty pound range for floors. For these applications it is not necessary to use their highest density structural panels as we rely on the encapsulation for the structural component but you will need to use Vinylester at the very least.

love this stuff, costs a little more but worth it. Way easier to work with and lasts forever.

http://www.spaceagesynthetics.com/

The floor was fabricated out of some kind of cellulose honeycomb coring . No Plywood , this was supposedly one of the 99 Race boats but we cant verify that. I was hopeing someone else had done this on their 33' and would chime in . The Fuel Tanks are mounted between the forward bilge bulkhead and the rear cabin bulkhead , and sitting on more rotten plywood .