I am excited about this boat. Not sure if my little changes will be enough to allow me to sit behind center as far back as I would like. That will be ok because what I have now works. I'm getting about as much out of this size boat as one could expect. It is 13' long with a 12' X 28" floor, and 34" beam.
A secondary goal was to build lighter. My experiences has shown me it is hard to build a full grown pirogue with traditional methods and materials below 50 lbs. Fiberglass and extra light weight wood can give you a lighter boat. This boat weighs 40.2 lbs. That is 11 lbs. lighter than my son's boat that is 6" shorter.
For this build I found and used "Exterior" Luan plywood.
https://www.stinehome.com/building-materials/plywood/sanded/
When I found this plywood at the store I was skeptical. Store manager checked their info and said it was rated exterior. Gave me some small scraps of 9mm and I did a boil test. It did not come apart. I used the 5.2mm for the sides and 9mm for the floor. After I bought the sheets I boiled a sample of the 5.2mm. It also held together.
Can't say this will work in the real world but I was confident enough to build with it. I will post any problems or developments if they happen.