Waste Tank Pump

Discussion in 'Boat Design' started by rasorinc, Jul 29, 2015.

  1. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    I know nothing about pumps except for submersible well pumps and my knowledge on these is old. I want a pump with a hard pipe to the 100 gallon waste tank. then a 2 way valve so I can drop a hose over the side for fresh water or salt water. On the discharge end I want to use a somewhat rigid hose 3/4" or 1" and drag that hose some 75' up a bank with a 40' lift max.
    After spraying the macerated waste far from the waters edge then turn the valve to suck fresh or salt water to flush the
    pump and extended hose clean. Maybe a hook up for a fire type hose sucking fresh or salt water.
    Any ideas on size and US brand names, pressures would be greatly appreciated. Thanks much, Stan. PS I will have 110 power and 12V. Waste will have been treated with chlorine in the tank.
     
  2. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    Just checking my understanding -

    You want to empty the tank with an onboard, permanent pump and discharge as described, then switch the inlet from the tank to a suction hose to purge the portable discharge hose.

    Some concerns - Tank vents. Most blackwater tanks are pretty flimsy and wont take the sort of suction head that might be needed to draw the freshwater onboard during step 2. It might be better to do the purge by refilling the tank with water and gravity feeding the pump. Or it might not be a problem at all, but check on the tank and make DARN sure you have adequate venting. I don't suppose the tanks and pumps can be installed below the waterline, can they?

    You really don't want to use a garden hose nozzle to spray the stuff. Keep it out of the air. If you pour it directly on the ground it will presumably kill everything it comes in contact with. So a dumpster sized pit full of charcoal and chips will be needed even if it is sanitized (or a septic field).

    Suggestion 1. Mount tank and pump below water line and allow water to gravity fill the tank (or use an a/c raw water pump) for purge. Use 2" blue flat hose for discharge (pool supply, etc.). Not sure how the mascerator fits in. Plumbed in a loop, or is all incoming waste mascerated?

    Suggestion 2. If the boat is plumbed normally (there are many good reasons to do this IMO) with a mascerator discharging to a Y valve with one leg to a deck pumpout fitting, then you could build a remote kit that fits in it's own box. Connect the pumpout fitting to a bladder in the box. Use a booster pump to empty the bladder as the mascerator fills it up. Store everything in the box. It's not like you will be doing this very often. And the normal boat plumbing leaves you with some plausible deniability should awkward questions be asked.

    Now if you can explain the suction side requirements/restrictions and flow rate and location of the stuff wrt the waterline, maybe the pump question can be answered.
     
  3. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    Thanks Phil for your input. I will make my own Waste Tank out of 3/4 WP ply with inside and outside corner molds and horizontal stiffeners with 3 layers of glass inside and 1 layer outside 12 ounce bi-ax cloth. It will be mounted 10' forward of the transom and under sole about 5" below the DWL. The pump is at the same level starboard side of the outboard engine. I will be able to run a straight hard pipe level to the tank. The waste will be treated so to make it inert but not poison enough to kill plant life if spread
    around. This boat will be used to explore US major rivers and lakes also off shore ocean in good weather not out of sight of land. The aft 16' is a flat Dory hull then 3/12 up to 7/12 pitch as it rises at the bow. Overall 8'-6" x 30'. I will be on it at least a month at a time or even longer. Does this give you further ideas? I need simplicity in the system as much as possible. The tank will be well vented and have a deck clean out for dockside pumping. Thanks much.
     
  4. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    You need a regular mascerator pump in the system somewhere. Downstream of that, a Utility Puppy 2000 would probably work for boost. Since you want a seawater pickup anyway, you might want to plumb an anchor or deck wash provision. Depends how squeamish you are. I would want separate hoses for sure, but I could live with sharing the pump. In effect, you have a conventional waste system, and a conventional deck wash system, and a crossover, perhaps temporary in nature. It requires 3 1" Y valves at about $50 each. But that's cheap for something that would get used a lot instead of once every two months.

    1" flat hose is available in fixed and random lengths with an assortment of connections. I'd go for the MIL-SPEC 1" stuff - about $125 for 100 feet w/o connectors.
     
  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    What do you mean by spraying the macerated waste far from the water's edge? Are you docked while you do it?
     
  6. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    No not docket--in the middle of nowhere. spray the treated waste 50' to 75' away from shoreline and up to 30' above. that is why I am searching for a quality pump that can do the job. I'm planing on using a macerated toilet to flush to the tank. Then a macerator pump to discharge out.
     
  7. gonzo
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    gonzo Senior Member

    If you have a Type I or II, check with the State for minimum distance from shore. If you have a Type III, you need to be 3 miles from shore, but the State may require more. A macerator alone does not comply with the law. For near-shore discharge it also needs to be disinfected.
    http://water.epa.gov/polwaste/vwd/vsdmsd.cfm
     

  8. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

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