Discovering new problems on my old boat, undersized wires edition

Ben Stein

Ben Stein

Publisher of, passionate marine electronics enthusiast, 100-ton USCG master.

9 Responses

  1. Dave Sylver says:

    Very enlightening surprised Carver said that could have happened.

  2. Tony says:

    I have the same set up in my Carver. However there are only two wires coming into the gray box. Where did you find any additional wires. Mine have gotten very short over time with people butt splicing as they have changed components.
    I am thinking the next time I have a failure, I am going to have to run new wires to that gray box. Not looking forward to that.

    • Ben Stein Ben Stein says:


      Mine had four wires from the factory. Two for the float switch, one supplying ground to the pump and the last positive coming from the manual switch in the engine room. One of the float switch wires and the manual wire meet somewhere under the floor and out of view or reach.

      So, if you only have two wires and they’re undersized or corroded you will likely have to run new wires and if it’s like my boat that wont be the most fun you’ve ever had.

      -Ben S.

  3. Grant Jenkins says:

    Good article and you raise an important issue. I too have discovered serious electrical deficiencies in “price-point” boats, not to name names, some much newer than yours. Invariably they all proudly displayed the NMMA “certification”, ostensibly indicating that they were constructed to ABYC standards.
    The sad fact is there is zero enforcement or inspection requirements to meet this “certification”, and in fact it remains entirely voluntary on the part of the builder. The boat buying public remains largely ignorant of this fact. Bottom line – buyer beware. Educate yourself so you know what you’re looking at, or hire someone who does. Even newer, factory boats can come with some serious short-comings….

  4. Scott Booker Scott Booker says:

    If I understand the problem correctly, they ran appropriately sized conductors for the actual pump, but undersized wires for the float switch?

    Did you consider just finding a happy-home for a 12V relay (coil driven by the float switch) and just call it a day?

  5. Ron Micjan says:

    I worked on a 42 Catalina where the owner noticed a flickering of the bilge pump run indicator light. Factory wiring had used standard crimps and tried to squirt silicone sealant into the ends then covered with split loom and electrical tape. Then the whole mess was dropped next to the pump in an inch of bilge water. Lasted a few years…

  6. Woody Fairley says:

    I offer a different perspective: why would the factory install a 2000 gallon per hour pump in the shower sump? My 1970 Chris Craft Commander has a much smaller sump box and it contains a much smaller pump. Perhaps a better approach might be to consider replacing the large pump with a smaller pump, such as the Rule Lo Pro LP900S which integrates the float sensor. The choice has served me well on a number of boats, and while I have to clean the bilge sludge from the primary pump’s sensor in the Chris Craft, it has outlasted all previous choices.

    Why continue to keep such a large pump in the shower sump?

    • Ben Stein Ben Stein says:

      I can’t disagree that 2,000 GPH feels like overkill. But, I’ve often noticed that larger pumps (and hence larger motors) prove more reliable. The pump in the sump is at least 10 years old, and likely original to the boats, and still going strong. Plus, it’s got a 1.5” discharge hose running to it that would require adapters. In this case, the pumps not broken — just the wiring to it was — so I don’t see a reason to fix it. Especially since fixing it would, at minimum, require cutting back the discharge hose and working in an adapter.

      -Ben S.

    • Grant Jenkins says:

      Woody, the author states the existing wire appears to be in the neighborhood of 20AWG. I can’t imagine ANY pump would draw a small enough current to make that wiring feasible. I think Ben has the right idea…

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