Marine ply floor replacement for zodiac 340 solid

[HK Fishhead]

I've just taken my sib out of storage outside and i've noticed two of the marine ply boards have water damage on the edges and have swollen so they no longer fit in the grooves when trying to click them together. I can't find any direct replacement as Zodiac don't seem to make this model or even have a contact address. I assume I will probably need to fabricate them myself? I went to the timber merchant and they had sheets of 12mm ply. I not sure if this is an exact match?However the boards looked as if they had only three layers of laminate. My existing boards look like they had far more layers
Should I be looking for a specific marine ply or would this be ok? I can cut it myself and give it a few coats of epoxy and then paint
I'm looking for advice as I live in London the timber merchants don't know anything about marine ply sib floors. Is there any where I can get these made up or of the shelf. Do zodiac have templates drawings? Or is this something I need to do 100% myself.

[Fenlander]

Zodiac are unlikely to have these boards as spares or offer drawings. But if you have the old boards as templates then making new ones up is very easy. Just match the thickness, buy decent quality regards of the marine label or not and seal well with your choice of paint/varnish/resin etc.

[HK Fishhead]

Thanks I just looked at Robins timber in Bristol a marine focused timber merchant that has 12mm marine ply with 9 laminate layers. Its about 170% of the price of the marine Ply excluding delivery that I looked at today which looked like only 3 layers. If I've got the max engine size of 20hp for my SIB the boards strength will be important so I think the 9 layers is what I need despite the price? I'll have to cut it myself and use the existing boards as templates. I think I'll use epoxy resin to seal and then paint the boards white as the other boards are white. All this comes at quite a price even if I do it all myself.

[Oldman2]

I dont have a ply floored boat but here is my thrifty thought. Im guessing this is quite an old boat (stored outside) so using a reasonable ply (not marine) or even 2 thinner sheets bonded together will give you the thickness and size from your pattern. Treat it well with epoxy and paint and if it lasts 5yrs and the boat is still in good order with intact transom, make another floor section from your pattern if need be. Keeps the cost down. Just my view from outside.

[Steve509926]

I dont know the Zodiac 340 but it is extremely unlikely that the boards are Marine Grade Ply, which was/is primarily used below the waterline.
There is so much confusion when it comes to grades of ply, even amongst timber merchants.
I would advise grade A-B WPB ply, made up of either 7 or 9 plies. Make sure all the cut ends/sides are well sealed before painting as that is where water ingress is likely.

[HK Fishhead]

Thanks that does make some sense. I'd need to see what the cost saving is. As the marine ply I've sourced will do the job but for a price. It has a 15 year guarantee (if that means any thing at all?). I also need to look at the strength aspect as I don't really know much about the differences in ply and other options just yet. It has to be water resistant I know (but treating it properly I assume can solve this?) and strong enough.

[Steve509926]

The major difference between Exterior Grade WBP ply (weather & boiling point) and Marine Grade Ply is is the number of voids within the ply.
Marine Grade should have no voids in it, Exterior Grade WBP is allowed a certain number and size of voids.
When buying try to ascertain what adhesive is used as there are two, melamine and phenolic, phenolic being the better and more expensive of the two. I would always try to buy phenolic, not that there is anything wrong with melamine, it is just a more resilient adhesive. Both External ply and Marine ply should be made using the same adhesive.
There is no such thing as a water resistant ply, it is the adhesive which is resistant, and as you have alluded to the final finish on the surface of the ply.
As for strength, for your needs it doesn't matter which you choose between Exterior WBP and Marine, providing its a good grade hardwood ply.
15 year guarantee? Will always be met with "did you seal it correctly" and "did you treat it every 6 months/12 months"

[909]

Makes no sense to replace entire floors boards if an edge or two is delaminated.

Dry it out

Clamp with epoxy glue

Sand then seal with epoxy sealer

Paint

You just saved yourself hours & hours of work and wasted money

Time is better spent on the water instead of fixing sh:it