It would depend on the construction of the craft, but as a general rule, the fiberglass boat will be heavier.
1937 by Ray Greene
becuase elmo killed the chicken king for the win
If possible, get to BOTH sides of the damage. Remove damaged material to the point that everything is solid and "feather" the back sufficiently that you can get a good bond, using a coarse sandpaper...
possibly i know that if it gets on your skin it can make you VERY itchy soaking it in water can help though