Epoxy or Polyester for Fixing Rotten Core on Deck?

A small 2-square-feet area around an inspection hole on the deck of my
fiberglass boat is kind of springy. I believe water has found its way
through the flange of the inspection hole into the core, and I believe
that the core has become rotten and has delaminated from the fiberglass
skin. I am going over books to learn the right way to fix this
problem. But I have a question that I don't know the answer.

According to the hull/deck repair books from WEST SYSTEM and Don Casey,
they both recommend using epoxy to glue the new core and the old
fiberglass skin. This makes sense because epoxy is good for attaching
dissimilar materials together. So far so good. Both books recommend
grind down the edges of the fiberglass skin to create tapered edges,
and then put fiberglass cloth and epoxy to link up the old fiberglass
skins together with the fiberglass skin on the deck. I buy the idea of
using epoxy to join the fiberglass skin. But I have a question on how
to finish the surface.

If we use epoxy to join the fiberglass skin, the cured epoxy is the
outer surface before any finishing is put on top of it. According to
Don Casey's book, gelcoat doesn't adhere well with epoxy. He suggested
painting with non-skid additive or attaching non-skid overlay over the
area to cover up the epoxy area. I am under the impression that paint
is not good for high traffic area, right? And I don't know how good a
non-skid overlay will look when it is placed on existing non-skid
surface. I assume that the existing non-skid surface is made from
gelcoat, and I would assume that putting gelcoat with non-skid additive
over that area will be better compatible with the non-skid surface on
the rest of the deck.

Is painting with non-skid additive good enough for high traffic area?

Can we sand the area and then spray a thin layer of gelcoat over the
epoxy and then add non-skid additive onto the gelcoat using a shaker?

What would you do to finish the area?

Thanks in advance for any info.

Jay Chan

> For purty, I think you're going to have to paint. What the limits of the
> painted area are depends on your esthetics. I have the impression that
> there are many paints suitable for high traffic areas. Porch & deck
> enamel?? Creative masking of the edges of the paint can make it look like
> something that was planned.

Good to know that some paint can withstand traffic. Honestly, I am not
impressed with paint that people put on porch or deck. They eventually
deteriorate after foot traffic especially near the stairway.
Therefore, I try to avoid using paint.

Hopefully, I can find some intermediate agent that I can put between
the cured epoxy and the gelcoat (that I want to put on top of the cured
epoxy), and somehow help them to bond together.

> If your existing non-skid is the sand-in-paint flavor, you can probably
> match the texture after a few tries. If it's a molded in pattern, then
> there is a scheme where you make a "mold" from an undamaged area and press
> it down into/on top of the fixing goop before it hardens. Seems like I've
> seen a write-up in one of the magazines recently for this technique.

Not sure how the existing non-skid surface was created. I will try a
couple methods to see which one comes close.

Jay Chan