|Cost and availability is an issue here in the US...... we don't have Finnfoam, we have Dow Corning, etc XPS insulation foam at 2 pounds per square foot density readily available.

HIGHLOAD 100 and FOAMULAR XPS 1000 (at 100psi compressive) is available all across the us. As are the lesser 60psi and 40 psi versions.

The chain store Menard's sells it. As do many other building supply stores.

Why would you say it is not readily available?

|There clearly is a place for lower density foams than H-80 and H-100, but again availability is a problem.  

Like we have discussed, why would one buy lesser than H100, when H100 is at the best price point?   

|Just as in an automobile, where the forward structure is designed to crumple and absorb the kinetic energy, XPS seems a nearly ideal crush material to absorb a bow on impact and prevent real structural damage.  

Honestly cheap XPS insulation is used cause its cheap, and works well enough.

|it simply is not worth using a foam that is not designated as a marine structural foam, not knowing what the longevity will be and how well it will perform.

Didn't you just say its perfect for bows?