John, I am trying to find out right now what people have used and what they experienced. AC Fir is about $30 a sheet where as Luan is $12 a sheet. I have heard that you are wasting your money on pressure treated and I am hoping that once the boat is glassed you will have all the strength that you need. It is amazing how fast this goes together. I was a little worried about getting the boards to bend for the nose but it's been so humid here that I just strapped them together and put some tension on them while leaving the frame laying in the grass for a few days. Every morning the dew was so heavy that the boards were soaked and I would tighten the straps a little more. This worked really well and I didn't have to wrap wet towels or soak the boards in a pond. One board did crack on the outside of the frame, not bad, and I hear this is pretty common. It is just a crack and not broken. I glued it and clamped it for a few days, looks like it will be fine. As soon as I have some more info, I will post what I decided to use. dc