Les Groby wrote:
The front hatch coaming on my old VCP Skerray RMX has partially
seperated from the deck and is leaking badly. Since there is no adhesive
that I know about available at the retail level that will stick to
polyethylene plastic (and I worked for a few years in hardware retailing
so I know a lot about adhesives), I need to come up with another way to
reattach it. Here's what I'm thinking: drill six or eight holes around
the hatch through the deck and the coaming flange; break the coaming
completely loose from the deck and clean off the old adhesive; apply a
sealant to the flange; then rivet the coaming back in place. No sealant
will stick very well to the plastic, but with the rivets to do the
mechanical work of holding the coaming in place, the sealant will simply
provide a "gasket" to seal it.
Good idea? Stupid? Give up and stick a float bag in there? Discuss.

I'm surprised that it's not installed that way to begin with. It's a
pretty common practice with VCP hatches. Typically, six fasteners are
used. Screws and nuts can be used, but flat head or oval head screws
will tend to split the flange on the hatch rim if they're overtightened.
If you decide to rivet it, I would be tempted to use aluminum rivets
rather than stainless, for the same reason. Stainless rivets create a
much stronger clamping force, which may be too much for the flange and
plastic hull. You'll probably want to put a dab of sealer on each rivet,
to prevent leakage.

BTW, there are now adhesives that will bond to polyethylene (3M makes
one), but they're not easy to find, they're expensive and they require
an expensive mixing gun (it's a 10:1 mix ratio).