It does not surprise me. In one of my old boats (23cc) someone had simply screwed a 4"x4" piece of plywood on the bottom of the boat and then went inside the cc were the old plumbing thru hulls were and poured resin over the holes. Let it cure then removed the wood on the out side. Went I went to fix it I tapped it once with a chisel and it popped out leaving me with two nice 1.5 inch diameter holes in the bottom of my boat.
I guess some people are just lucky.
Strick