I live in Huachuca City, Arizona. I think I will go with marine grade as I really don't have a choice. If you saw the quality of plywood available here you would have nightmares for life. If I owned a mill I would be ashamed to sell it. The birch looks great but I think it is interior stuff. For dimensional lumber I have the whopping choice of some unknown variety of pine and maple, or poplar.....Back in Washington I never had a problem with wood as fir was everywhere. I love fir. Even the exterior plywood was pretty good stuff. Built a few boats out of it with very good results. In rural Arizona things are more of a challenge. Even the choice of glue has me wondering. I want one that can stand up to high heat. The sun here really does a number on any type of exposed wood and sometimes it is not possible to keep a boat covered. I guess I need to start getting my ducks in a row and make some choices. For the framing I guess either the pine, maple or poplar would work but the plywood is going to be the most critical component of the boat. On that I just can't scrimp on. I have never build a boat using marine plywood. Always a first time ay? Has anyone ever tried poplar for boat frames? I have almost aways built stitch and glue boats and while thats great I miss working with wood that a more conventional type of boat provides. Back home I worked mostly with fir, spruce and hemlock. I cannot find it here. I know nothing about pine, maple or poplar...I ask the clerk what types of pine and maple they sell and they just look at me with a blank stare.....Have I mentioned I love fir?.......