Side comment that I forgot from the previous post. It released the
built up pressure from the tank quickly when I took the vent tube off
the holding tank. I also verified that the vent was clear going back
into the holding tank when I removed the vent tube. I used a
screwdriver and there was nothing there.

Peggie Hall wrote in message ...
Mollie wrote:
I've got a 35ft sailboat. With a 20 gallon holding tank under the
quarter berth. My vent is blocked and I can't use my head. Flushing
(which I have ceased until I fix it)...

The right thing to do...

just expands the holding tank
(not good).

Definitely not good! 'Cuz that can result in anything from an eruption
in the toilet to a burst tank.

I found some blockage at the holding tank outlet in the
tube. There was enough extra that I cut out about 3" and put it back
on. Still blocked. I can crawl into the lazarette and see the hose
(it's fairly translucent) but I can't detect any blockages.

Most likely it's the thru-hull that's clogged. The two most common
places, especially on sailboats, are the vent fitting on the tank and
the thru-hull...caused by waste spilling out the vent while heeled.


The
tubing also has a foul odor and I want to replace it.

That won't cure any blockage in the thru-hull, but it's a good idea
anyway. Use sanitation hose, not clear hose again.

I can't get at
the vent thru-hull because it's just below the toe rail and in a spot
I can just barely reach with my fingertips.

You should be able to clean it out with a screw driver blade from the
outside...but you will have get to it inside the boat to replace the
vent hose.

I was thinking it might be
easier to install a new thru-hull.

Also a good idea, but you'll still have to get to the existing one from
the inside of the boat to remove it and to the inside of a new one to
put a new hose onto it.

I was thinking of putting the new
vent in the cockpit with a SeaLand inline "holding tank vent filter"
installed below decks to eliminate the chance of odors.

Noooo...vent filters are a bad idea on any boat because they create the
very problem they're sold to solve by restricting the flow of air in and
out the vent. They're also expensive--over $50/each...they only last one
season at most...and they're "toast" immediately if they get wet--which
makes 'em an even worse idea on sailboats that spill tank contents out
the vent when heeled...and makes it impossible to flush out the vent
line regularly to keep it from becoming clogged.

Also, I'm not sure what you hope to accomplish by installing one...'cuz
they won't cure any odor problem inside the boat, only odor out the tank
vent.


My proposed
location is in front of the helmsman's seat about 3 feet aft of the
holding tank vent opening and about 8" - 10" below the toe rail level.
The vent line would run aft under the quarter berth about 18" and
down about 6" then make a slight turn and go up about 3 feet then turn
aft and gently rise another 6" to the proposed vent thru-hull
location.

Again--nooooooo! You want the tank vent line to be as SHORT and STRAIGHT
as possible. Your plan has at least 3 90s in it, is at least twice as
long as needs to be, and goes the wrong direction from the tank...it
should go forward, not aft.

What would Peggy say?

Yikes! Let's explore the right way to do this...Where's the tank
located in the boat? How far from the head?

--
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
http://shop.sailboatowners.com/detai...=400&group=327