I never built a model of the Briggs, but would guess the area you are referring to is in the middle of the boat between frames 5-6 or 6-7? Are we thinking of the same areas here? It would appear that the boat goes flat in the middle, like it should, but it didn't all go together exactly like I thought it would. It still works and I'm still happy with it though. I would love to get my hands on a table of offsets from Brad or Andy. I never did finish the blog, but put lots of pics up on my Facebook page and a few here when I finished it.
It makes its' inaugural run down the Grand Canyon in early March. Let me know if you run into anything and want to run it by an amateur like me.