"Jonathan Ganz" wrote

I took a look at the WM site and found an example of a vented loop. Looks
like it might fit, but I'm not sure where yet. It can either be within a
foot or so, or it would have to be at least 3 feet away in the engine
space. I'll have to check it out.


The vent has to be above the discharge and waterline for there to be any
point to it. "within a foot or so" would be OK if you just mean the lateral
distance and not the hose length. The loop should be just as high in the
boat as you can get it, ideally, just under the deck. If your bilge
discharge is high enough above the waterline, you don't really need a vented
loop except to keep surveyors happy. My bilge discharges are just ahead of
the transom and nearly a foot above the water line so I haven't added vents
to the lines which loop even higher under the cockpit coaming. It's
something I'll probably do before going very far off shore though. If the
boat was low in the water due to flooding and the pumps stopped, a back
siphon could be created.

--
Roger Long