For the choice of the material to use for the hull of a blue water sailboat the ability to withstand impacts is a key feature.
Since the scientific material in circulation is not too simple to interpret, some years ago, we did an empirical test to qualitatively verify the resistance of two types of materials.
We made two samples, one made of marine plywood laminated with bi-axial e-glass fabric with epoxy resin and the other in sandwich with laminated bi-axial e-glass cloth with epoxy resin and PVC core 80Kg/cm density.
Then with a 6-gauge shotgun loaded with a single buckshot we did shoot the two samples bearing the rifle barrel at about 10 meters from each sample.
Sample front
In both samples, the bullet penetrated without breaking through, causing substantial damage to the outer skin. The sandwich sample (one on the right) presents the most extensive damage.
Sample back
The marine plywood laminate sample (on the left) has a delamination (separation of the inner skin from the core plywood) in correspondence of the zone of impact of the bullet.
The sample sandwich with PVC core is completely intact and there are no signs of delamination of the inner skin.
What happened is that the core of marine plywood being rigid transmitted most of the impact energy to the outer skin making the damage, while the PVC core has absorbed all the energy of the impact.
In the event of a collision at sea (for the same energy) the hull in marine plywood would no longer watertight and in the area of delamination would begin to filter water inside the hull, while the hull in sandwich would remain watertight
