What’s going on in your bilge? While you’re running your boat, perhaps you notice the stream flowing from the tell-tale thru hull. Or maybe you hear the pump sucking air and then remember to turn the switch off — yes, that same switch you meant to turn on for only a minute about an hour ago …

Maybe you have a “bilge pump on” idiot light? That works, and lets you know that the good ol’ pump is doing its thing.

We all have our personal tricks to ensure that the sea water stays on the outside of the boat, and barring disaster, those usually work when we’re enjoying our boats. But do you ever wonder what’s going on in your bilge the rest of the time, when you’re not aboard?

You left the boat on Sunday afternoon, and after a thorough washdown and unloading all portable gear, you’ve headed home, and you won’t see your floating baby until next weekend. As you’re driving, you’re focused on the fluke that got away, the bass that was right at the boat, the fun time the kids had skiing and tubing … and then, for a brief moment, the questions flash through your mind: Did I turn the battery switch off? Did I lock the cabin door? Is the hose back on the dock? All worries are soothed by the thought that, well, my bilge pump will do its thing — just in case. Right?

So, here’s a fast, simple and inexpensive project to keep your mind at ease. Install a bilge pump counter that will tally each time the auto switch senses water and turns on the pump. They come in 12 or 24 volt variations, depending on the voltage requirements for your vessel, and are available at most marine stores.

Simply measure your bilge counter and cut a hole in the desired mounting location, preferably in a dry space where you will have instant visual access once aboard. This counter will become one of the first things you look at when you board the boat, and the last thing you check when you leave (to reset it to zero). The counter has a bezel so there is some leeway for overcutting, but not much, so be careful.

The counter I have been using requires a small rectangular hole started with a ¾ inch hole saw to cut the center and then a small hand saw to square off the edges. You can also use a RotoZip or Dremel tool to make the cutout.

If your vessel has an indicator light for when the bilge pump is on, you can simply wire the counter right to the indicator light, saving the need for a bilge level connection. Otherwise, be safe, and switch off the main and backup battery switches and turn off the auto bilge pump breaker. Just be sure to leave a sticky note on the helm that says, “batteries are all off/disconnected.”

Locate your vessel’s existing auto float switch and find the power wires. They are often grey in color, or brown and brown striped, depending on the manufacturer. These will be in the bilge and near the pump, so they will be easy to locate.

Cut the POS cable from the auto switch and connect the red conductor with a length of 16/2 marine grade wire by cutting the existing connection at the existing splice (I prefer to replace the existing butt splice with a 3-way splice and then re-seal the entire connection, but you can also use a vampire connection anywhere along the wire — just be sure to thoroughly seal the splice with heat shrink tube and/or sealant. I use 3M sealant tape). Connect the other wire (black) to the black ground wire leading from the existing bilge pump in the same manner as above. Run the length of cable through the boat to the desired mounting location and through the back of the hole you cut, leaving enough cable to make your final connection.

Connect the new bilge counter switch to the 16/2 cable and seal with heat shrink or sealant (I always add an inline fuse on the red cable, with the fuse removed until the task is completed). Now simply slide the switch into the neatly cut slot for a dry fit.

Once you confirm a proper fit, put a bead of clear sealant on the back of the bezel, put two small mounting screws in the pre-drilled holes, install the inline fuse, and you‘re all set.

Switch your batteries back on and hit your bilge pump switch. The counter should click off each time the switch is hit. Your new visual watchdog is now in place and ready to alert you to an overactive pump. Just press the reset button each time you leave the boat and remember to take immediate action if the counter indicates that there is more activity in your bilge than the typical rain drip, or shaft log weep.

David J. Mahler
was licensed as a captain at age 16. After running a charter
fishing company he got a degree in marine science and entered the business world. He is a staff officer in the United States Coast Guard Auxiliary.  

This article originally appeared in the August 2018 issue.