[deepsushi]

Fred,

I did not put the ribs back in. I did get a little bounce / deflection without them so I am going to pull the hatch back out this spring and glass in some stiffeners. I think I am going to use some 1 1/4 " pvc pipe ripped in half as the stiffener "base" and glass over it with some 1708.

I considered using one of the composite products as a core. However, the composites are a lot more expensive than plywood. Th original plywood lasted 30 years and it only failed due to the exposed plywood edges that allowed water to penetrate into the core.

Cutting the plywood into squares accomplishes two things:

1.) it eliminates any warpage in a full sheet of plywood.
2.) it is a much more efficient use of material. I recored the whole hatch with 2/3 of a sheet of plywood. If I utilized larger pieces I would of needed at least two sheets of plywood using large "whole" pieces.
3.) the theory of the alternating grain orientation is that it will prevent water intrusion between individual core pieces ( I am skeptical of this as every square was fully water saturated in the hatches I have done in both my 18 footer and the 23 footer.)