An argument here concerning someone shooting a 12 g shotgun at a
sailboat at various distances. At close range, no argument, 00
buckshot would go right thru the fiberglass. At what range would it
not penetrate?
What about slugs?

In article b66ab558-3782-47db-ac5f-
,
says...

An argument here concerning someone shooting a 12 g shotgun at a
sailboat at various distances. At close range, no argument, 00
buckshot would go right thru the fiberglass. At what range would it
not penetrate?
What about slugs?

Depends on what it was made of.. A few years back a guy built a "bullet
proof" boat over at rec.boats.builders... He tested some of the panel
material with a bunch of firearms, the biggest I think was a 45, and it
did not penetrate... But that boat was somewhat over-engineered...