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Bilge Question-gctid358988

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    Bilge Question-gctid358988

    I had some stench coming from the bilge. So I pulled out at least 20 gallons of of nasty water and sponge cleaned with bilge cleaner. Now my rear bilge pump is mounted on a block of wood so the float is pretty high.. I can take on over 20 gallons of water before the rear pump float is activated. I am Interested to hear opinions on the placement of the float.. I a leaning towards lowering down into the bilge.. I would appreciate any opinions, experiences, thoughts etc on the subject before I decide how to proceed. I have a 1985 3870... As always Thank you in Advance for your input.

    You need a small bilge pump like a 360 jabsco with an enclosed float switch mounted in the bilge just fwd of the engines near the bulkhead, you may need to clean the bilge and glue the bottom removeable portion of the pump to the bottom of the keel, same with the float switch, the switch should be slightly higher than the pump. That pump is a 5/8" hose size, you will also need a thru hull and a fuse, I installed a seperate fuse with no disconnect for power, but I also installed a switch for manual turn on, there are small panels for this connection.

    Bayliner 3870 "ALASKA33)
    Twin 350 GM power
    Located in Seward, AK
    Retired marine surveyor


      As a general answer many of us use a layered approach using two or more pumps and switches.

      The lowest pump and float switch would be the smallest pump. This pump is to keep the bilge dry from normal water such as rain or wash water entry.

      The higher pump and float switch would be a larger pump. This pump is larger and the float is set higher so it would typically only run if a large influx of water occurs. This keeps the pump clean , dry and ready.

      I like the Water Witch bilge pump switches for the lower pumps as they prevent short cycling and keep the pump running 10 seconds past the point of being "dry" to clear the water from the bilge.

      Also with the lower pump a check valve in the output hose will prevent water coming back when the pump turns off. The purist will say not to use a check valve as it might clog. But the check valve keeps water from running back and forth from the pump really helps to keep the bilge dry. I have personally never had a check valve clog but I keep the bilges clear of dirt and debris. Also if you have checks in the bilge hose I put a little antifreeze thru the pump during winterizing to be sure no water is left in the hoses to freeze. Even if the lower pump completely failed you have the upper pump.

      For the upper pump and float a warning alarm is prudent because if this pump is running something is likely wrong and needs attention.


      Regarding pumps

      I am not a fan of pumps with the float built in. If the switch fails the whole thing must be replaced.

      There is also a style of small automatic pump that runs for 1second every 2minutes to test for water. We had one of these and it made me nuts. Vvv.......................Vvv..................... Vvv..............................Vvv.............. ..............Vvv I was happy when it died.
      Jim McNeely
      New Hope a 2004 Bayliner 305 Sunbridge Express Cruiser
      Twin 5.7s with Bravo2 drives
      Brighton, Michigan USA
      MMSI # 367393410


        I also have a 1985-3870. It has 2 automatic pumps & 2 smaller Rule manual pumps. I think this is how these boat were set up. The manual pumps are in front of the automatic ones & lower in the hollow keel. Do you have switches on your dash panel marked fwd. & aft. pumps? Maybe someone removed manual pumps. Pumps are in engine room [aft.pump] & between center berth &galley.[fwd.pump]. Access by small panel at foot of bed. Small pumps are needed as air conditioner condensation runs into hollow keel. Hope this helps.. Greg.


          In a previous thread on this subject the concept of using a diaphragm pump was offered. This is a pump like you probably already have for your fresh water system but it uses an L shaped rod with the bottom of the L in the 38 bilge which normally is hard to drain dry with a regular bilge pump. One poster suggested a timer set to run once or twice a day rather than a float switch because it is less critical if this runs dry.

          Last year I bought a small regular pump and mounted it within the bilge hollow and run it manually once a day. This also worked.

          I am a bit puzzled by the small issue. Seems to me in a 38 there is enough leakage from various things including air conditioners to keep that bilge water fairly fresh. Be careful that you have not developed a leak in your waste holding tank or anything attached. Most 38s had a macerator pump installed and many were decommissioned. Look this over too.


            Thanks for the input folks... I read the other thread and Jim invention sounds good... This project starts right after Varnish.. New Alternators and oil/filter change tomorrow. Sunday sand,chip, and paint engines. Monday replace blowers, then prep-work for Varnish.... Then Bilge pumps, fuel sending units and polish and wax.. Hopefully done for Memorial weekend, headed to the Island! today i re-installed the auto pilot and and replaced the temp and RPM senders... It never ends!!


              Yes I was the one that wrote of using diaphram pumps to really keep the bilge dry.

              In my own boat I have three pumps in the engine bay each at a different level. The layered approach I mentioned earlier.

              I have a total of 6 bilge pumps on board.
              • Forward Bilge Scavenger (Low Level)
                • 3 GPM Timer and Helm control ÔÇ£Scavenger PumpsÔÇØ
                  • The timer runs the pump for 1 minute in the AM & PM
              • Forward Bilge (Middle Level)
                • 750 GPH Float and Helm control ÔÇ£Fwd Bilge PumpÔÇØ
              • Mid cabin mechanical space bilge (Low Level)
                • 500 GPH Water Witch Solid State control only
              • Aft Bilge Scavenger (Low level)
                • 3 GPM Timer and Helm control ÔÇ£Scavenger PumpsÔÇØ
                  • The timer runs the pump for 2 minutes in the AM & PM
              • Aft bilge (Middle Level)
                • 1600 GPH Water Witch & Helm control ÔÇ£Aft Bilge PumpÔÇØ
              • Aft bilge (High Level about 3" off the bottom.)
                • 3600 GPH Float Switch & Helm control ÔÇ£Emergency Bilge Pump"

              This photo shows the aft bilge and the three bilge pumps. The copper pickup is centered on the transverse bulkhead in the lower edge of the photo.

              The diaghram pump is to the left , my mid level pump is in the center and my hi level pump is to the right.

              The black pump with yellow knobs is my oil change pump.

              Here you can see the copper pickup for the diaphram pump.

              The copper pipe is capped at it's end. The horizontal tubing is slotted on the bottom to suck water from as low as possible.

              My timers control the scavenger pumps. I am keeping the bilge so dry float switches would be useless.

              Yes the enclosure is cheesy but the lid snaps closed. The bottom slopes down to drain if water ever did make it inside which is virtually impossible given where it is located and covered.

              The complexity of the controller was due to making the setup such that both pumps can be manually controlled with a single helm switch. In hindsight I could have simplified the wiring and eliminated the relay with a Double Pole helm switch.
              Jim McNeely
              New Hope a 2004 Bayliner 305 Sunbridge Express Cruiser
              Twin 5.7s with Bravo2 drives
              Brighton, Michigan USA
              MMSI # 367393410



                that is a pretty impressive system.. I appreciate the photos they will help.. I really like the copper pipe idea, keep the water and stench out..