"Michael Porter" wrote

But watch brass (as opposed to bronze) fittings carefully -- athey are
subject to turn into red dust in salt water. Just keep a close eye.


I'll more than second that. Since this is a raw water line and operated at
elevated temperaturs due to being in a cooling circut, it absolutely should
not be brass. Even though it won't sink the boat if it breaks, water rising
in the bilge could be a dangerous distraction in a difficult situation. The
breakage would also be accompanied by exhaust leaking into the interior of
the boat. You won't be able to keep a close enough eye on the interior of
the fitting where the problems will be.

Even if this is just a seldom used overflow that seldom sees salt water,
it's still exposed to exhaust gas on the other engine cooling water.

This is the place to invest in bronze. Brass should only be used in F.W. and
fuel lines.

--
Roger Long