If it just small cracks then laying down more cloth is probably
overkill. I'm going through the same kind of exersize after
removing my teak decks. If the old surface is gelcoat, then
laying cloth over it is a bad idea. The gelcoat will have to be
removed to get to the existing glass. The secondary bond
characterists of resins over gelcoat is not good. The
solution that I am using is applying 2 coats of epoxy barrier,
then a 2-part polyurethane finish.

Doug
s/v Callista

wrote in message
...
I have a houseboat whose roof has a bunch of thin
spider cracks, as well as some a bit bigger. The
biggest ones aren't wide enough to get any more than
a razor knife blade in, if that. I want to put some more
fiberglass sheet on it, and have never done that before.
Having talked to several people about it, the following
is pretty much the impression I've developed about
doing the job, and I'd appreciate any more suggestions
or advice people are willing to sha

· First, use something like a thin wheel on a grinder and
dig out the larger cracks, then fill them in with rosin to
make them strong...if that's not done before sanding,
the cracks will fill up with dust and never get strength
from rosin entering them.

· Sand the area with medium grit sandpaper.

· Clean area with acetone.

· Cut fiberglass cloth to fit the area, then staple in place.

· Saturate the cloth with rosin using a roller. Best to set
up a cover like a tarp, because in direct sun the rosin
could set up too quick.

· After all that has been done and dries, apply gel coat
...I've heard to apply 1, 2 and 3 coats, so as yet don't
have a good idea of how many to apply.

One of the things I'm still trying to figure out, is how to
deal with the excess rosin which will want to drip down
the side of the boat. Can anyone suggest any good way(s)
of dealing with that issue?