Cindy Ballreich wrote:
Our holding tank is about 10 gallons and is located under the starboard
settee. The connection for the vent hose is at the forward end of the
tank. The hose runs back to an outlet about 3 feet aft and 2 feet above
the tank. This gives a rather curvy, mostly horizontal hose run of about
6 feet. Air can enter and leave the tank for filling and emptying, but
there isn't any real "air circulation" to prevent odors. It looks like
there might be room to put a new connection at the aft corner of the
tank which would shorten the hose run by 2.5 to 3 feet. The tank is
fiberglass or some kind of very hard plastic. (It's been painted so it's
difficult to tell what it's made from.) We think the tank is probably 20
years old and was custom made for the boat when it was built. The vent
hose appears to be 1/2 inch ID.

Cindy, your best solution may be to re-route the vent line to a new
thru-hull forward of the tank. The fitting on the tank is already in the
best place for it...running the vent line forward in the shortest
straightest line possible would help a lot, especially if you can still
keep the rise under 45 degrees and the line length at 3' or less.

Where in the boat is the tank? If it's under the v-berth, a vent line
forword is definitely the best plan.


So here are my questions:
1. Would shortening the hose by this amount make any real difference in
the air circulation?

The shorter and straighter the vent line the better...however, running
aft, shortening it up prob'ly won't make much difference.

2. Would modifying the tank cause any problems with its structural
integrity?

No...new fittings are installed in tanks all the time. But without
knowing for certain what the tank is made of, I can't tell you how to do it/

3. Assuming the answer to 1 is "yes" and 2 is "no", how should we go
about adding the new connector and removing the old one?

I wouldn't remove it...I'd send it to a new thru-hull forward of the tank.

--
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://69.20.93.241/store/customer/p...40&cat=&page=1