Sven,

I don't know if this would be appropriate in a marine environment, but
for painting metal, and would work on ANY surface as far as I can tell,
is 'Devflex' by ICI. If I recall correctly, ICI is a Sherwin Williams
company. I've used it many times on commercial upfits on painted
metal door frames as well as only primed frames. The stuff is
excellent, hardends/cures faster and harder than oil based paints and is
a latex which can be used over oil or latex paints. It's top advantage
is also its highest disadvantage. It dries immediately! I have found
that if I start at one end of a door frame, by the time I've finished at
the other end, I can begin the second coat. Again, I don't know about
marine use, but it is an inter/exterior paint. If you use it, I'll warn
you now, if you get it on you, forget washing it off like you would a
normal latex based paint. Wait until you take a shower and it'll come
right off.

-JimL