Roger Long wrote:

But, then the pump out boat and the marina pump out have to pull the
sewage through the pump. The pump out at our marina has enough
trouble lifting the stuff 15 feet at low tide. I don't want to add
the head loss of a pump to it. A self priming pump won't pass stuff
that way anyhow.

As I said, Roger...my brain burped...it's the vented loop, not the
y-valve, that goes between the pump and the thru-hull. The y-valve, of
course, goes ahead of the pump...there'd be no reason to put it after
the pump.

Sorry for the confusion...
--
Peggie
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Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/books...ku=90&cat=1304