waste pumpout

Dec 2, 1997
8,708
- - LIttle Rock
Peggie for power on the cart I would have just ran an extension cord
I don't THINK it's quite that simple 'cuz shore power only supplies 115v AC power...Electric pumps intended for use aboard are all 12v, 24 or 32v DC (most boats have only 12v) requiring some kind of "converter" or buy a cheap car battery to power it.

20 posts into trying unsuccessfully to find a way to empty your tank without your having to expend any energy, methinks the easiest solution would be: Just bite the bullet and accept the need to use the manual pump on the cart to empty your 80 gal holding tank, but do it when there's only about 20-25 gallons in it instead of waiting till it's full. If it already has a lot more than 20-25 gallons in it, just pump that much out each time. If you're living aboard alone, you should only have to do that about once every two weeks unless you're using a lot more water to flush the toilet than you need to.
--Peggie
 

Jim26m

.
Apr 3, 2019
579
Macgregor 26M Mobile AL
Peggy is correct. If you pick a 12 volt pump, you will need a converter; https://voltage-converter-transform...MItLq07uLD4gIVzODICh10cwMvEAQYFyABEgLgEPD_BwE, such as this. Or, you can rig a 10 amp, 12 volt outlet up in your boat - conveniently located near the waste connection, and run off of your house batteries. If you decide to go the converter route, make sure you mount it in an approved location, or appropriate enclosure. Remember, water and electricity don't play well together.

At 4 gpm, 80 gallons will be 20 mins of pumping. Actual draw for that pump is around 6.5 amp, so consider the power draw if you use batteries. If your house bank has the juice, that would be a good way to do it. Peggy's suggestion to pump more often (one tankful on the cart), would be my preference as it would reduce the amount of power needed at any one time - giving your batteries plenty of time to recover and not using a days power for poop. But you may have a huge bank that can do it.

The cool thing about it is, you may figure out why the cart pump wasn't performing when you pressurize the suction hose and diaphragm (see twalker's post on previous page). I would wear glasses and keep your mouth closed for your first pumpout.:). In fact, I might use a momentary switch for the first test...

You'll need to monitor the process to prevent spillage when the tank is full.

Good luck! And happy pumping!
 
Last edited:
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
Folks, there is a handy little pump readily available that is fast, does a great job and is probably already on the boat. It is called a macerator pump! Just put the outlet hose of a macerator pump in an empty tank, turn on the switch until full, then go empty the tank. A 6 gallon fuel tank or water tank works fine for this. And yes I am an engineer!
 
Dec 19, 2006
5,809
Hunter 36 Punta Gorda
Most macerator pumps are chopping up and it is a down ward pumping out maybe
not made to pump up ward and you are dealing with some messy smelly stuff so be careful.
Is there some place else to pump out like a pump out boat like we have here in Punta Gorda
or go to a marina who has a better pump out.
Nick
 
Dec 2, 1997
8,708
- - LIttle Rock
Macerator pumps can lift up to 5', Nick. And there is no "chopper" in 'em. An impeller pulls the waste through a "blender" blade that purees any undissolved solids and/or TP. You might want read the specs and spend a little time studying the exploded drawing in the owners manual. Jabsco Macerator Pump owner manual
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
To speak to the OP questions: Original vacuum idea is workable but without someone evaluating the dockside tank for "external pressure" (vacuum inside is difficult to design for and most plain tanks would collapse if external pressure is applied) you'd be gambling on a uuuuuhhhh BIG crappy MESS. The other part, applying a vacuum would need something with a lot more volumetric capacity than a refrigeration compressor .. a small air compressor hooked up to pull a vacuum would have enough capacity.. something like this: https://www.harborfreight.com/3-gal-13-hp-100-psi-oil-free-pancake-air-compressor-61615.html
That little guy would do a flow rate in round (rough numbers!) 5-6 GPM out of the boat holding tank as long as the dockside tank did not collapse.. The vacuum system would pull the stuff through the existing hand pump; it has what looks like joker valves which let the stuff go through the pump in the normal direction.
 
Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
I'd bet real money that Rick is an engineer... 'cuz normal people believe that if it ain't broke, don't fix it....engineers are convinced that if it ain't broke, it either doesn't have enough features yet or they have to keep reinventing it till it does break. :biggrin:;)

--Peggie
(I DO hope Rick has a sense of humor, 'cuz he only joined sbo.com yesterday and it's a bit soon to start treating him like family!)
Why have 2 moving parts when 10 can do the same thing.