I know Finnish quality controll is top of the world, but I have no idea about the quality of French made plywood (or Latvian for that matter). I can by it at local hardware store. Its supposed to fullfill the requirements, but... Especially the question is about the glue thats used. The problem is also that local hardware store sales people know about building houses but not about building boats, so they play it safe and don't give any promises.
What I have learned sofar is that actually the whole concept of Marine Plywood I read many talking about in the forums is outdated... Basically all Finnish made plywood is good enough, unless its especially made for indoors purposes... It mostly has to do with the glue all Finnish manufacturers use in making plywood and also on quality control. The rest comes from epoxy and paint. The problem arises, when the hardware store does not know where his stuff comes from originally as its the wholesaler that takes care of that. He just orders the next batch of plywood. To me that means that I would have to make sure about the quality by doing the boiling test myself.
I have also learned that there is no real need to buy any Okoume or Meranti plywood, at least for the Hull as it gets first saturated with epoxy and then painted. I could of course use some imported Okoume for some deck details if I want to have some "marine" appearance. If I want the boat to look like a million dollar yacht, then Okoume would be nice, but there is no benefit except appearance, and for that you only need the top veneer to be okoume. To use the expensive stuff I would have to design the "style" of appliances etc to match the Yacht-feeling, but I dont want to triple my working time.
An additional point is that some 50% of tropical wood is cut illegally and some 70+% of Okoume is illegally traded and its already been put on the warning-list as some 20% of it has already disappeared during last generations.. Its not in danger of extinction yet, but its on the path because of the illegal irresponsible global market.
Finnish Spruce beats Okoume in needed qualities and all manufacturers use good glues that you can boil for as long as you like without any delaminating, except for the plywood thats intended for interior use as the better glue does not look so nice as the interior glues. If I need something harder I can use Birch... Either stuff that has only the top layers from Birch or the stuff that is all Birch. Thats the stuff they use for aeroplanes. So why should I pay 5-10 times more for the imported stuff?
Okoume has no benefits except appearance to spruce plywood. Spruce is one of the three standard bulk plywood choices available. Basically they make 3 types of plywood here: Birch, Spruce and Conifer. Spruce is better than Okoume for boatbuilding because its about equal in strength but lighter and withstands rot and fungi better, and its cell structure is better. When I talk about Conifer it means its a mix of Spruce and Pine-tree both of witch are good enough. Tollman recommends Fir plywood. I guess Conifer would be the closest equivalence. We don't have any naturally growing hardwood here in Finland. Birch is nice looking and I guess you could call it "semi-hardwood". Its mostly used for indoors purposes, but its not naturally as resistant to rot and fungi as Conifers.
About the BS 1088. As a British standard its not used here, but the quality it stands for is contained in newer standards. For us in Scandinavia the problem is most often that our standards are higher than those used elsewere in Europe and the world. Its a problem, because it tends to give a price advantage to others, eventhough its also a good thing. The letters WBP stands for the boiling test compliance.
Here is a quote:
"The vast majority of Finnish plywood is of cross-banded construction bonded with phenol
resin adhesive. Normal gluing quality is suitable for use in exterior (service class 3) situations
when properly protected. A small part of Finnish cross-banded plywood production
is bonded with urea formaldehyde glue. These boards are suitable for use in dry (service
class 1) or humid (service class 2) conditions.
The phenol formaldehyde gluing fulfils the requirements of EN 314-2 class 3 exterior.
The gluing quality may still be referred to earlier national classification such as DIN 68705:
BFU 100 or BS 6566: WBP."