what pump for black water tank discharge?

IMHO, the black water tank pump is one of those components that you really don't want to have to replace any time soon so buy the very best you can afford. Whatever you buy must be capable of dry running for extended periods without damaging the mechanism and obviously it must be capable of handling solids. I fitted a black water tank system in my boat 3yrs ago and I was recommended to buy one of these
http://www.nonstopyacht.com/static/browse/session/Product/View_/GNR&2DECO&20MV&2044&2D12.htm
It was expensive at the time (around €700 if memory serves) but it's worked without problem so far

Mike that's prob what I should fit. But does it self prime to say 700mm, with just air in the pipe? Your link doesn't say. Does you tank-emptying pipe exit the top or bottom of black tank?
 
ok, reviving an not so old thread...

following the discussion on the Match2 thread, JFM suggested that the black water tank exit should be below waterline.

J, the original setup had 3 manual toilets, all exiting via gravity just above the waterline. No black water tank (er, and a half cut 10lt originally bucket for grey water shower... sinks straight out)

Current setup is:

16lt Whale grey water tank (2Xshower 2Xwashbasin) with an exit above waterline via a whale gulper 220 and with a 30cm swanneck thing


108lt black water tank by plastimo (iirc), a Rheinstrom MGR 1.5inch diaphragm pump ....and here's the issue a 1.5inch skin fitting (for above waterline exit)
There's also a odour filter and an extra exit which I'll place further back around the mid of the e/r (some 4m away from the tank)
Route from the tank which lives slightly offset at the keel under the mid cabin was planned to be just straight to port side (say around 2m long special non-permeable rather expensive pipe)

Pete says the problem with above w/l exit is the smell, I think I can live with that assuming I mainly empty the tank on the way at low D speeds
I'm not so keen on a below waterline exit as that means yet another seacock and not exceptionally easy routing AND forgetting to open the seacock and pressing the empty button :eek:

so, above or below, this is the Question!

cheers

V.
 
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