Holding tank vent line(s)

I am having my new holding tank and head completed this winter and I was wondering if anyone had any thought about the following:

In Peggie Hall’s article, http://boatbuilding.com/content/sanitation.html , there is an interesting discussion in there about using two holding tank vent lines for increased airflow (in order to keeping anaerobic bacteria in check). Has anyone done this and/or what do people think of this idea?

Also, is there a de facto place for the vent thru-deck on the BCC?

Cheers,
Paul

Peggie Hall’s idea is very sound. The setup does require a means to pump a small stream of air into the black water via a sparge tube fitted near the bottom of the holding tank. I like the idea but it does add another level of complexity to the holding tank.

rod

Paul,

We installed the new Ronco 13 gallon model 125 waste tank under the samson posts a year ago, actually had to cut the post shorter, build a retaining bulkhead and and make new deck hatches to cover the chain locker.

We installed the thru-deck waste pump-out fitting just aft and to port of the port side samson post, it drop the hose directly down to the stand tube on the tank.

A simpler approach to getting more air to the waste is to install a larger vent hose-1" and thru-hull fitting.

Hi, Paul,

I hate holding tank odors and our boat is our home. I thought Peggy Peal made a lot of sense, so when we set up Galatea’s holding tank system, we spec’d a tank with two 1.5" vents and put a bronze thru hull port and starboard in the walestrake. They’re nicely green now and don’t seem obtrusive to me, and I haven’t had any lookers ask about them.

We did find that, especially sailing hard to windward offshore (in big waves), the lines would fill the tank, so I fitted valves to close the vents when we’re at sea. Otherwise, we have excellent ventilation and so far, no odor problems.

Tom
SV Galatea