Garland Gray II wrote:
Now that I think about it, the survey (it was a 6 month
old demonstrator boat) didn't make mention of this deficiency.

If the toilet is completely above the waterline, it wasn't.

It was almost completely below waterline.

In that case, it WAS!

I expect that the water between the vented loop and the bowl that is higher
than the top of the bowl eventually drains to the bowl, to be replaced by
air.

But not before it stagnates in the anaerobic environment inside the
hose...and could very well stay till it's flushed out if the wet/dry
valves in the toilet is working as it should. However, you're
overlooking the water that's also left in the intake tank between the
thru-hull and the top of the loop, that has nowhere to go till it's
flushed out when the seacock is opened again. I suspect that's where the
worst of the problem occurs.

It's easy to solve: Tee the head intake into the head sink drain. Flush
using sea water...then, when leaving the boat, after you've closed all
the seacocks, fill the sink with clean fresh water...flush the toilet.
Because the seacock is closed, the toilet will pull the water out of the
sink, rinsing all the sea water out of the WHOLE system (just pouring
water down the toilet only rinses out the head discharge line...it
doesn't ever get into the intake). Or, you can flush with fresh water
all the time by keeping the seacock closed and adding water to the
sink..though you really don't gain anything over just flushing all the
sea water out before the boat sits.
--
Peggie
----------
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://www.seaworthy.com/store/custo...0&cat=6&page=1
http://shop.sailboatowners.com/books...ku=90&cat=1304