HAS ANYONE EVER TRYED USING PVC BOARDS. THEY COME 4X8 SHEETS IN ALL SIZES FROM 1/4 TO 3/4 AND ARE WIDELY AVAILABLE IN MY PART OF THE ISLAND. MOST CARPENTERS ARE STARTING TO USE THEM BECAUSE OF THE BUG PROBLEMS IN THE CARRIBEAN ISLANDS. MARINE PLYWOOD IS OUT OF THE QUESTION (IT HAS TO BE IMPORTED, THEREFORE THE SHIPPING COST IS MORE THAN THE WOOD ITSELF) AND THE BEST ACX COMES FROM HOME DEPOT.
What you're talking about are the cellular PVC products being used in land based building projects.
These materials are fine for replacing the boards in a porch deck (at 3 times the cost of wood) or the siding on a house, but it has no strength.
If you check the product descriptions from the various manufactures of these products you'll see they call it a "non-load bearing" and non-stress products.
In simple terms, it's heavy, much heavier then plywood. It's weak and can't be used in structural applications, in fact it can't even support it's own weight. It can't be structurally glued (welded maybe,if virgin or has limited UV exposure). It expands and contracts dramatically (much more then wood), making it unsuitable in tight joint applications. It also doesn't hold fasteners worth a darn.
Given it's limitations and cost, it's unlikely it will do more then replace trim, moldings, balusters, decks and fascias. In other words it's a decorative material only.
THANK YOU FOR YOUR IMPUT, YOU JUST SAVE ME FROM WASTING A FEW HUNDRED DOLLARS ( AND FROM DROWNING). WHAT ABOUT THE LESS THAN QUALITY ACX AVAILABLE IN MY AREA. IS THERE A WAY TO TREAT IT TO MAKE IT STRONGER.
Please don't use "all caps" as it's very difficult to read and seems like you're yelling.
ACX is one of the lowest quality plywood's available. Attempts to make it "stronger" will also make it thicker and heavier. It's more of a quality issue then a strength issue. Most every supplier will make special orders from time to time.
Look around for marinas and boat building shops. Make friends with them and see if they can order some quality materials for you. There are lots of both in Puerto Rico and I'm also sure you can get BS 1088 and 6566 grades on the island, though it appears you haven't found them yet.
One alternative to investigate is salvaged wood. A lot of imported product would be arriving in crates (at least historically) and even though the pieces are of a smaller/odd size they are often of pretty good plywood.
You'll spend a lot of time making scarf joints but it might just be a cheap alternative.
Any decent plywood will do. Marine is nice, however many of these boats have been made from lower priced lumber. I used a mix of G1S, and utility grade plywood, six years later my Vacationer is quite solid. As Andrew mentioned crate materials could be adapted, your only limit is your ingenuity.
Greg
Thank you, to all those that took the time to answer my questons. It´s a true testament to the good nature of all the boat builder/owners. The passion everyone has for these boats and the willingnest to share your experience is a great comfort for all newbies
Today, being my day off from work, I took the time to visit a couple of marinas in the area. I was greeted very well and of the older gentlemen there even drove with me to an out of the way lumber store that had exactly the marine plywood (IN STOCK) that I needed.
 Tommorow there will be saw dust in the garage.
Once again thank you.
Quote:Look around for marinas and boat building shops. Make friends with them and see if they can order some quality materials for you. There are lots of both in Puerto Rico and I'm also sure you can get BS 1088 and 6566 grades on the island, though it appears you haven't found them yet.
I love it when a plan comes together . . .