No question about that. Any half way decent designed hull varies in thickness from deck to keel. When we installed the depth sounder transponder at about 8" ahead of the keel and roughly 3" off the c'line, we had to use a deep hole hole saw and go in from both sides of the hull as the solid glass was about 3" thick (BTW the wing keel is bolted not encapsulated. The hull sides (for at least 8" above the waterline is over 1.5" and the local repair guy (who repaired Irwins -his shop was right next to the NE Irwin dealer) told me I had at least another inch to go when I carved a 1" deep gash in it (the fuel tank being on one side of the salon and the water tank on the other) in 25 to 30 kt winds I have never had flexing, but I have a friend that delivered a 40 something CC and got thrown from the bunk due to hull flexing. There is definatly a difference from Irwin to Irwin, just like anyother boat. Actually, if you look at the design specs for the newer glass boats, they are making the a damn sight thinner that they used to. To me, stringer location and size, bonding methods, fillet radii at joinings and hull to deck joints are what make the big diff.. Check this out.
Looks pretty good to me, if they actually did it that way. I know mine is thru bolted.