I have to be honest, I don't understand Glastron's thinking...each of my flotation boxes had 4 rubber plug holes in the top, which allowed water to come in. I'm assuming that's where they injected the foam after the boxes were glassed in...so I get it...but they were essentially built to fail.
I suppose if you're building to a 10 year usable life or something, they accomplished that goal.
Anyway, Red, here's what I did with mine...I filled all voids under the floor with pink foam...should water ever get in, there is drainage from bow to stern, but, I'm pretty good about keeping my boats dry.
Anyway, here's what I did, floor is 10x more solid then it ever was, and I've added more flotation as well.