A bilge pump counter, or bilge counter, is a simple device that can alert you to small or frequent leaks on your boat.
Most boats large enough to have an inboard engine also have through-hulls and other means by which water can enter the boat. When you are on the boat, it can be difficult to find and correct a leak once the water becomes deep enough to obscure visibility in all areas. If you are off the boat, even a small leak can wear down the battery running an automatic bilge pump and allow water to continue to accumulate.
To guard against the problems of leaks, consider installing a bilge counter, a bilge pump alarm, and/or a bilge high water alarm . These three systems work in different ways and offer different benefits, and you may want to use more than one. This article describes the use of a bilge counter.
Start with an Automatic Bilge Pump
Every boat gains from an automatic bilge pump that comes on when an internal or external float switch or sensor indicates water has risen to a certain level in the bilge. On many boats the bilge pump is wired into the electrical control panel, tempting the owner to shut it off when leaving the boat or at other times - defeating the whole purpose of being an automatic pump. Or even if the switch is left on, the power to it may be cut if you shut the main battery switch off when leaving the boat, as generally should be done to prevent losing power to a short or other systems left running.
A simple solution is to wire the automatic bilge pump directly to one of the boat's batteries with an inline fuse. No matter what is done with the panel or battery switch, the pump will run as long as the battery has power. The only downside is that the pump may get stuck on and drain the battery completely (and/or overheat the pump). If you have multiple batteries the risk is minimal if you shut off the battery switch so that they are not connected in parallel to the pump. The risk is preferred to potential damage from a leak when you're away from the boat.
Why Use a Bilge Counter?
A bilge counter is a simple device, usually digital, that counts how often the bilge pump comes on. It is particularly useful for monitoring water ingress when you're away from the boat. Water may accumulate slowly from condensation inside the boat, or sources such as ice melting in an icebox that drains into the bilge, and the pump may come on a limited number of times while you are away. But if it's coming on more often, go looking for another leak.
A counter is also useful when you are on the boat if you do not have a bilge alarm. On my first cruise in a recently purchased sailboat, in which I had just installed a bilge counter, a fitting in the head sink drain broke just above the water level, such that each time the boat heeled on a gust, a gallon or more spilled into the boat. The bilge pump was handling it, but with the noise of wind and waves we never heard it come on. After a couple hours I noticed the bilge counter was at 17, which spurred me to go looking for the problem that may otherwise have gone undetected.
Simple digital counters simply count up from zero and can be reset. Other models show cycles per day, week, etc. Except to pay from about $55 to $80, unless you're willing to search hard online for a generic "totalizing counter," as they are called in electronic components. (They are mostly available wholesale in lots, as they are often a component in various equipment.) But the commercial marine models are generally more rugged and usually worth the slightly higher expense. (See sources below.)
Installation of a bilge counter is usually simple, and you can run the wire alongside the bilge pump wires. Follow the instructions for the model you choose, remembering to locate the counter inside the cabin in an easily noticed place.
If you are building your own system, you need only a 12-volt counter and the appropriate wire. Like the bilge pump, it is better to wire the counter directly to a battery (use an inline fuse) rather than through the electrical panel. Wire it so that when the float switch completes the circuit to provide power to the pump, it also provides power to the alarm. Each time the switch turns on, the counter counts up by one. Remember that the counter does not signify how long the pump stays on, so it cannot alert you to a serious fast leak. Have a bilge pump alarm for that.