Larry Bradley wrote:
Late getting into this - just got back form a summer on the boat. We
live on the boat all summer, and the holding tak gets a lot of use -
odor isn't too bad, but the 1st mate complains about it all the time.

My first question is, do you have odor inside the boat? Out the tank
vent? Both? 'Cuz they're two entirely separate issues. The tank--unless
it's leaking--cannot be the source of odor inside the boat, 'cuz odor
from inside the tank has only one place to go: out the tank vent. So any
change in tank venting or holding tank product to try to eliminate odor
inside the boat is just chasing your tail.

The system is 34 years old. The tank is polyethylene, I think, and
appears to be in good shape. The hose from the head to the tank is
real heavy red hose, and it too looks to be in good shape.

I know of no hose rated for sanitation use that's red. As for how it
looks, that's no indication of whether it's become permeated with
odor...and if you do have odor inside the boat, it's a pretty good bet
that it has.

The tank is
behind the head - the hose run is about 3 feet, most of it vertical.
Since we have a relatively small tank (maybe 15 gallons), we put as
little water through as possible, so we can go for a week to 10 days
between pumpouts. However, this procedure leaves some liquid type
waste in the hose.

That's because you don't flush long enough in the dry mode move the bowl
contents all the way into the tank. Any marine toilet that's working
anywhere close to factory specs can move waste at least 6' in the dry
mode...and should have no trouble moving it 3', even if the hose is
vertical.


I've been using the traditional head chemicals, of the "kill
everything that moves" variety, and have just started heading about
this product "Odorloss". I gather it is one of the enzyme thingys. IfI
want to switch to this, what is the best way to get all the old
chemical out? Just flush, pump, flush, pump?

Yep...that's the only way. Odorlos is not an enzyme product...the active
ingredient is nitrates, which promote oxygen release from the waste,
creating the necessary aerobic conditions to allow the tank contents to
break down without producing any odor.

My tank vent setup is dumb - a right angle at the tank, then about a
six foot run of 5/8" hose forward, then a vent.

A foot or so longer than I'd like it to be and half the diameter, but a
single 90 fitting on the tank is no problem as long the line is straight
and there isn't another 90 at the thru-hull.


My head and tank is just forward of midships. I could run a vent hose
to a vent in the hull right there - about 1 foot of hose. I don't know
if there is any way to install a larger vent connection to the tank.

There is...and it's gotten a lot easier to do since a li'l doodad called
the UniSeal hit the market that makes it a piece of cake to install a
new fitting in a poly tank. Check it on the mfr's website he
http://www.aussieglobe.com/avs96.htm This company also makes the best
sanitation hose on the market--AVS96...16x more resistant to odor
permeation than any other hose.


Would just shortening the hose help?

Anything you do to improve ventilation inside the tank will help to
eliminate odor out the vent...but it won't help odor inside the boat a bit.

Should the hull vent be one of
the kind with the small holes and the screen, or should I just use a
plastic through-hull?

Use an open bulkhead fitting...1" diameter or larger.

I want to keep the 1st mate happy, and a nice smelling boat helps.

Try cleaning your bilges and sumps. You'd be amazed at the number of
people I hear from who've torn out/replaced their entire sanitation
systems trying to get rid of what they thought was "head" odor...when
just cleaning the sumps and bilges was all the boat needed...'cuz irty
bilges and sumps can make a boat smell like a swamp, or even a sewer.

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