On Mon, 10 May 2004 15:21:17 GMT, Peggie Hall wrote:

good comments snipped

It does require two vents, and the fan should be be an
exhaust fan that pulls air through, not one that pushes air into the tank.

Peggie, I wondered about your statement above...until it occured to me
that you're entirely correct. The reason (tell me if I'm wrong) is that by
sucking air out, a slightly negative tank pressure is created. This prevents
odors from escaping into the boat via the vent loop, (or any other "air leak"),
which it would if the tank had positive pressure.

I'll probably try this when I (finally) get my own boat, but I'll be sure to
make the fan easily replacable, since I suspect the "fumes" will be
somewhat corrosive.
Norm B.