I need to update the
holding tank systm on my
Hunter. It currently has a V-shaped
holding tank below the
water line. Sewage can be discharged via two top
ports that have tubes that go to the bottom of the tank. One is
pump out, the other has a hand
pump to a long vented loop to the seacock. It's not working. It's not an actual waste pump, but rather a
water pump and it would be hard to put a real waste pump in the
current space. I really don't like the
lift system anyways.
I have room to install a 6 or 9 gallon tank horizontally that would be just above the
water line. I've thought of doing that and having it gravity empty. I've had a gravity feed system before and also used it on many
charter boats. I like it: open the thru-hull and drains. However, those
boats had vertical
tanks with an inline, larger than normal discharge. On my
boat, this system would have to have a horizontal tank and and an aproximately 6-foot almost horizontal run to the sea cock with standard 1 1/2"
plumbing. My concern is that with such little pressure, sewage may not discharge and a lot of gunk will settle along the horizontal bottom of the tank. (The old holding tank had about 1/2 of sludge everywhere). While it would have little pressure, it also occurs to me that a tank barely above the waterline, might benefit from having
raw water flush back up when sailing,
cleaning things a bit if one leaves the valve or sea cock open. (4 week - 2 month cruises moving most days) The through
hull is inconveinetly located under a bunk, so I'd probalby use a y-valve or ball valve just below the tank to empty it.
Any experience with similar systems would be appreciated. (tank just above water line with 1 1/2 gravity discharge)
(Optoin 2 is to keep the old tank, install a Y-valve to
overboard or tank options. I mostly sail the
Bahamas where discharge is usually okay - but I do prefer to hold and dump when not in bays, etc. I really dislike having to hunt around for pump out optoins. Space would make it hard to plumb for
overboard, tank pump out and tank overboard. Option 3 is to get one of those Sealand MSD heads that are kind of a cross between portipotis and real heads, that flushes into it's own 5-gallon holding tank below which can then be pumped out. I like the simplicity. Don't like having to hand fill the flush resevoir (2.5 gal.) and wonder if a system with so little water introduced would pump out easily. Any experience with these also apprecited.