Here is my
holding tank installation on a
Searunner 40 tri. The
head is in the forepeak (foredeck
hatch above, heavy duty lid above
toilet for working headsails in heavy weather). The tank uses two 1 1/2" vent hoses led to each side of the bow, following the concepts of Annie Hall's aerobic digester design (uses aerobic bacteria to process waste - great idea!). The waste enters from a
Lavac toilet, via a Whale 10
bilge pump (which thoroughly macerates paper and waste), and enters the tank from above. There is also an
inspection plate, should an eager ICE inspector wish to confirm I had no drugs or illegals hidden there. Waste flows by gravity to the lower hose (with a tee for a
deck cleanout port), then through a plastic ball valve (lockable in closed position) then
overboard at the boottop. The only moving
parts are the lids, the
pump handle, the three rubber
parts in the Whale
bilge pump, and, of course, the ball valve handle. No electrics or significantly maintained systems. The big black stacked pumps on the left are the saltwater
deck washdown
pump (using the head's seawater intake throughhull).