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) just expands the holding tank
(not good). 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. The
tubing also has a foul odor and I want to replace it. 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. I suspect it is blocked
up at the thru-hull but can't prove it. I was thinking it might be
easier to install a new thru-hull. 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. 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.

Does anyone have any thoughts or criticisms on this proposed method?
What would Peggy say?

In advance,
Thanks