That's a difficult question to answer. It all depends on how much work went
into the installation of the fiberglass bottom. If the bottom was prep'd
well then the resin will have a good bond with the bottom. In this case,
you'll likely tear off some of the bottom along with the fiberglass. On the
other hand, if it was not done well, then it may peal off OK, but there will
still be places where it will take some wood with it because it
"accidentally" sealed well. It might be best to plan on sanding the
fiberglass off rather than trying to peal it off, but the glass dust can be
a killer! Leaving it on is usually not a good option because if ANY water
gets between the fiberglass and the wood, it will rot the bottom. You have
some hard decisions to make!

Don Dando