I called Gougeon Bros. regarding that chart in "On Boat Construction". Their comment was they hadn't really done extensive testing and the table was basically "preliminary". The man I talked too suggested that I not place too much faith in the data as tests were not too well controlled.

I tried graphing what little data was there and could find no real relationship between any of the parameters.

In the future (I've been saying this for a while now) I intend to do some testing on panels of different thicknesses and lay ups. I think it is necessary to get a real handle on the strength.

Part of my problem is deciding exactly what to test and how to test it.

For example I don't think the material used in rotomolded boats is that strong, however the boats are very rugged. Because the material flexes so easily the boats don't get hurt when they bounce off of things. While I don't think this same mechanism will protect a fiberglass or strip-built boat, it does pose a problem when you are deciding how to test.