Here’s my two cents on plywood selection. I have two points.
1) A lot depends on how you’re going to use the boat. If she’s going to be docked outside for the summer, you definitely need marine plywood. If she’s going to be garage kept, or dry under a tarp most of the time, you can get away with other materials.
2) Lumberyard fir plywood checks. I would never use this on any of my boats. I did on a dinghy I built years ago. It was stored outside, under a tarp, and it checked anyway. On the Duckworks FB page, lots of guys are building with this stuff. I’m tired of warning them. Don’t do it.