Again, send me a PM or Email if you need help with a project. Not to sound boastful; but, I have experience with about every boat material for building production boats in use. I have worked with them in numerous applications and uses.
My first recommendation would be to try not to use any plywood. It is extremely inadequate for modern boat building unless you use close molding or Resin Transfer Molding Processes. You might as well just use regular plywood if that is your intention.
The key issues are encapsulation and through hole protection.
Both will rot and degrade if exposed to water...marine grade just slows the process somewhat. I personally think it is a complete waste of money to buy marine grade plywood for boat building applications.
Of-course; all of my rationale is based on scientific and recorded data. Most of it is privileged from companies I have worked with in the past so I cannot post it online.
However; I can guide you forward if you let me know what you plan on using it for in your application.
“Every human has four endowments- self awareness, conscience, independent will, & creative imagination.
These give us the ultimate human freedom... The power to choose, to respond, to change.”