Boat Hull reinforcement

Is using fiberglass cloths a good idea to reinforce a boat hull?

Depends what the boats made of,if its glass then yes if abs then no.
Mart

Use it all the time in my scratch wood builds. I use epoxy resin instead of polyester, stronger and doesn't stink up the house in the winter.
People put a layer of carbon fiber in the bottom of a lot of the mono hulls as a stiffener. I'm a dinosaur I still like rails in a boat.

lotta guys use carbon fiber cloth with west systems epoxy too on the floor of rear hull in monos helps a ton.

What happens if you fiberglass over abs plastic?

It just doesn't bond to the plastic well. I've not done it myself, but have heard you can wet out the fabric with CA glue instead of epoxy for abs hulls.