Replacing wooden deck on pontoon boat

I have a 1993 Tritoon 266 pontoon boat that i need to replace the plywood deck and carpeting. This boat is 8.5 feet wide and 27 feet long. My problem is that in my area it is virtually impossible to find marine or any plywood sheets that are 8.5 feet wide, the standard being 4 by 8 sheets. In your opinions would it be okay to utilize 8 ft sheets by cutting them in such a way to stagger the seams the length of the boat. If you only had 8 ft sheets what would you do that would still be structural strong? Thx in advance, Greg

 

If your pontoon has the usual seats along the perimeter, that is a good location to hide the seams. Staggering them is a good way to build a deck.

 

Would it be feasible to align the 8' sides lengthwise on the boat, and have a 6" wide 'gap' in the middle?
This gap could then be filled with a 6" wide strip of material, and you could have a 12" wide strip of material underneath to act as a 'butt block'?
Glue the butt blocks and 6" wide strips in with epoxy.

As a substitute for plywood, here is a rather left field suggestion. How about using standard 3/4" thick PVC foam boards instead? I am thinking of the type that has a laminate on each side of the foam core.
These are very popular here for all sorts of applications in the marine world that would have otherwise called for marine plywood.
I helped a pal here fit a top deck on his glass bottom boat using these 3/4" thick sheets - after laying them down, the joints were glassed over (on the above side only), and then a carpet thrown over the new deck, and this worked very well for a few years - until it had to be taken apart when the (plywood) boat had to be re-built........ and even with just the joints overlaminated, these sheets were plenty strong enough to walk on.
This PVC top deck had replaced an exterior grade plywood deck that had been fitted only a year earlier by a 'professional' boatbuilder - and this deck had started to rot away merrily almost from day 1 of it being in use.
For extra strength and abrasion resistance, you could laminate the whole deck with a layer of cloth and epoxy, and then it should last forever. You would have to 'scuff up' the PVC laminate first before applying the epoxy - I did this, and it bonded very well.

I also built a wheelchair ramp for a friend using this same 3/4" thick PVC board - I covered the ramp with a layer of stitchmat (I don't know what the weight of it was - it was what was available here at the time) bonded with epoxy, and then painted it with non skid paint. This was 10 years ago, and the ramp is still in good condition, despite a lot of abuse over the years.
I know that this is an unconventional way of building a deck (or a ramp), but I simply suggested it, as it worked well for the above mentioned applications.

 

A foam core deck would create a lot of problems to screw back on all the furniture and deck hardware. It is also much more expensive and less puncture resistant.