Holding Tank Vent Question

[CruiserDave]

I am redoing the sanitation system for my O'day 35. I have your book and it has been helpful. The existing system has developed quite a smell. I had the whole thing redone 2 years ago by someone who, it turned out, did not know what they were doing. I am using the Raritan PHII and working with Ronco plastics for a holding tank, doubling the size of the existing tank (13 gallons). I have a question about venting the holding tank. I now have a 5/8" vent located starboard side approximately midship. I am uncomfortable increasing the size to 1" +. My concern is having an open hole that large on the side of my boat and taking in water in heavy seas. If I add a second vent to the port side, 5/8" perfered 3/4" if need be, will this work? Another question; were regularly cruise to the Bahamas for the winter, I would like to have a direct discharge and the ability to pump overboard from the holding tank, am I adding more work than needed? Thanks for your help.

David

 

[Peggie Hall HeadMistress]

Where will the tank be located?

If the head is forward, the best location is the v-berth...and the vent line forward, out the bow.

If the head is aft, we'll have to figure out how best to vent it.

 

[Jim McD]

David,

Having just refinished my plumbing system from the thru hulls up (with Peggie's expert advice), I can answer two of your concerns.

Vent Size ~ my boat (Beneteau 461) had a 5/8" vent- totally inadequate. I increased the size to 1-1/2" ( a Marelon flush thru hull (http://www.forespar.com/onlineCatalog/2009/Marelon/marelon_thruHullConnectors2009.shtml) without a clam shell cover, about 6" below deck line, with as short a vent hose as possible, about 6"). If any water was to get in through this vent, it would go directly into the holding tank (15 gallons each, I have 3). Once full, it would not allow any more outside water in (a closed system). In actuality, this has not been a problem for me, even in heavy seas. One vent per holding tank is sufficient (if properly sized).

Direct Discharge ~ My boat was originally equipped with a "Y" valve that allowed for discharge directly over board or to the holding tank. I eliminated the "Y" valve and now all waste goes to the holding tank. I can dump this directly (discharge from the bottom of the holding tank to a thru hull) or by pumping (I installed a "straw") from the top of the tank via a deck fill pump-out. (http://trioniccorp.com/index.php?option=com_content&task=view&id=32&Itemid=40)

Hope this is helpful. Listen to Peggie!

Jim