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Bilge Pump Discharge Location, Vented loop & Cored Hull

Discussion in 'Big Boats' started by Genesis V, Feb 19, 2018. Add this thread to a FAQ

  1. Genesis V

    Genesis V

    Joined Mar 30, 2013
    52 posts, 0 likes
    Hunter 356
    CA Georgian Bay
    I am installing a rule 2000 as a high water Backup emergence bilge pump on my H356, I am looking to locate the discharge fitting at midship close to and at the same height as the existing bilge pump fitting, which is about 3ft above the water line and heel angle. Should I still install a vented loop given the height. Also does anyone know if the hull is cored in this area and how to deal with it.
     


  2. Capt Robbie

    Capt Robbie

    Joined Jan 24, 2017
    242 posts, 89 likes
    Hunter 34
    Us Red Bank NJ
    I would still do the vented loop plus I would also install a check valve at the pump. I'm am planning to do this on my boat hopefully this year.
    Don't know if the hull is corded probably not.
     


  3. SG

    SG

    Joined Feb 11, 2017
    946 posts, 136 likes
    J/Boat J/160
    US Annapolis
    When you drill the hole (AFTER YOU'RE REALLY SURE), you should seal the core with epoxy where the hole cuts through the hull. That would be the same for a cored and in-cored hull.

    You want a vented loop as high as you can make it. The check valve is more for the backflow back into the bilge from "short cycling" the pump. What does the existing discharge have?
     


  4. jssailem

    jssailem

    Joined Oct 22, 2014
    5,217 posts, 1,662 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    The Check valve on a bilge hose is fraught with issues. It would be great if all you pumped from the bilge was clean water. But it is a bilge. And sooner or later your going to pump something that is not water. It will lodge in the check valve and then you will not be able to pump your bilge. Better to leave the check valve out of that hose line.
     


    FastOlson likes this.
  5. SG

    SG

    Joined Feb 11, 2017
    946 posts, 136 likes
    J/Boat J/160
    US Annapolis
    You need a strainer on most bilge pump inlets. That's especially the case with electric pumps. The check valve usually will stick open from debris. The valve does reduce the flow a bit.
     


  6. Genesis V

    Genesis V

    Joined Mar 30, 2013
    52 posts, 0 likes
    Hunter 356
    CA Georgian Bay
    The exit discharge is going to be a straight SS 1-1/8” mushroom fitting. The float switch is enclosed in a housing and both the bilge pump and the float switch have strainer bases. So a vented loop is still recommended I see. The check valve info is interesting.
     


  7. Benny17441

    Benny17441

    Joined May 24, 2004
    5,342 posts, 299 likes
    CC 30
    US South Florida
    Check valves are prone to failure and should not be used for bilge pump plumbing. Could not have explained it better than Jssailem. Understand that the small electric pumps are rated in a workbench under ideal conditions with no discharge loads. In real world conditions the pump will have to work to push the discharge water for a linear distance and a couple of heads of lift through the resistance of the discharge hose. While working the pump will generate heat and a drop in voltage which induces a loss of efficiency. These rotary pumps at best can actually produce around 25% of their rated capacity. That impressive 2000GPH pump may only deliver around 500GPH or 8 gallons a minute. I cringe every time I hear the words "for emergency" in conjunction with these small bilge pumps. These are merely convenience pumps to discharge incidental water that accumulates in the bilge and will not have the capacity to fight any significant intrusion of water from a hole in the hull or a fouled thru-hull or hose. At best they could delay the inevitable for a very short time in the hope someone may notice the boat riding low in the water or listing. They indeed could save the floor boards from water damage in slow leaks. For emergencies manual, high volume gusher pumps are utilized or 120V powered sump pumps to run with a generator. I endorse the idea of having a backup water pump but see no reason why it should be any larger than the primary. If I were to install a 2000GPH pump in a boat it would be in a 22' or under boat as the small boats will fill and swamp much faster that the larger boats. Your h356 should have an OEM emergency gusher pump to be operated from the cockpit with a detachable handle. Some install 120V sump pumps to run them at the dock with shorepower to protect the boat when unattended. There are other bilge pumps that are more efficient as well as expensive; a diaphragm pump can deliver closer to their rated capacity and can be very reliable. make an informed choice according to your needs.
     


  8. Don Lucas

    Don Lucas

    Joined Jan 12, 2011
    697 posts, 15 likes
    Hunter 410
    US Salem MA
    This check valve fear is crazy. Every sewage pump station in the world the pumps have a check valves and they rarely fail, especially if they are the ball type. So unless your blige is nastier than a sewage pit put one in and stop being such a worry wart over unlikely things.
     


  9. SG

    SG

    Joined Feb 11, 2017
    946 posts, 136 likes
    J/Boat J/160
    US Annapolis
    That impressive 2000GPH pump may only deliver around 500GPH or 8 gallons a minute. I cringe every time I hear the words "for emergency" in conjunction with these small bilge pumps. These are merely convenience pumps to discharge incidental water that accumulates in the bilge and will not have the capacity to fight any significant intrusion of water from a hole in the hull or a fouled thru-hull or hose. At best they could delay the inevitable for a very short time in the hope someone may notice the boat riding low in the water or listing.

    For emergencies manual, high volume gusher pumps are utilized

    Have you ever used a high capacity pump? Do you think you'd get x strokes a minute for very long to match a "high capacity" electric pump? ;^))).

    Also, those manual pumps aren't immune from "head" load. The physics of lifting and/or pushing the water out still is there. (i.e., you have to do the "work" to lift the water). The difference is you're providing the greater number of "watts" with each stroke -- until you can't work that fast.

    There is no question that an unobstructed 1-1/2" hole in a boat 2' below the waterline will send an impressive amount of water into a hull! That's a function of the depth below the surface (pressure) and cross sectional area.

    The loss of real world performance for the advertised "rating" of almost all bilge pumps sold on the retail market is mostly a function of the height of the water from the pump to the vacuum breaker. The "ribbing" on many bilge hoses (to facilitate installation), the length of the hose, and number/nature of bends in the line, etc. add frictional loss. (There's an esoteric issue of "good" siphon effect behind the pump, but my hydraulics is a bit fuzzy. ;^))))

    I believe that various offshore safety standards require at least one manual pump usable from the cockpit; and one from inside the cabin. That's in addition to other electric pumps. (The manual pumps are to be permanently mounted with available handles, "close at hand". If you have a "big" Edson, or other, moveable pump, that's in addition.)

    There used to be an expression to the effect that, "There is no faster bilge pump than a scared sailor with a bucket."
     


    jssailem likes this.
  10. artboas

    artboas

    Joined Jun 1, 2009
    1,074 posts, 56 likes
    Hunter 49
    ca toronto
    I would go with the Whale IC pump with remote bilge attachment.
    Here are the benefits:

    It's a Whale gulper, which means you van basically pump old socks through it without any strainers, etc
    The pump is out of the water. Only the remote head is in the bilge.
    The head has a built-in joker valve, essentially a check valve. Eliminates backflow.
    It is a "packaged solution" All you need to do is hook up hoses & power. It manages everything for you.
    Yes, there are less expensive bilge pumps, but nothing as complete, failsafe, and ready to roll. This will work reliably forever. I highly reccomend this solution.
     


  11. Whatfiero1

    Whatfiero1

    Joined Mar 29, 2017
    184 posts, 31 likes
    Hunter 30t
    US littlecreek
    My theory on emergency water pumping. First if boat has hole find hole and stick something in it . Shirt , sock or bung works best hammered into rigid object. But back to pumping. For those of us with inboard engine hope to use that pump to pump out water have trident hose run to bottom bilge with a strainer type screen on end goes to "T" inline raw water with valve. Use to winterize also . Hope to shut thru hull cut on bilge and keep motor above flood. All while heading for travel lift
     


  12. LeslieTroyer

    LeslieTroyer

    Joined May 20, 2016
    1,518 posts, 473 likes
    Catalina 36 MK1
    US Everett, WA
    My take on the check valve debate is..... this is for a high water pump, which is one you never ever want to come on because that means you got big problems else where. In the unlikely event water does get to the point it kicks in you want it to flow. Each hose connection and bend is going to create more reststance to flow decreasing your flow rate. Leave out the check valve, if a small amount of flow back that’s what the primary pump can remove!! Aim for flow, but keep the vented loop so you don’t sink the boat with the tool to save it.

    Mahalo

    I’ll let others debate check valves on the primary.
     


    jssailem likes this.
  13. artboas

    artboas

    Joined Jun 1, 2009
    1,074 posts, 56 likes
    Hunter 49
    ca toronto
    I agree.
    The fact that the Whale IC has a built-in check valve doesn't do anything for me. The reason I swear by it is that the remote head with sensor is a great design. Plus, it won't clog with debris