Bilge Pumps, Part II
escape, which may present a health risk for those
living or working aboard your boat. Also important is
the risk that mercury presents to aluminum and steel
vessels. When exposed to mercury, aluminum and
steel corrode; mercury is a metal and acts as the
cathode, while the steel or aluminum is the anode.
Thus, if your steel or aluminum boat (particularly the
latter) is equipped with a mercury-bearing float switch,
consider replacing it with one that’s friendlier to metal
vessels. The redesigned switches are mercury free, and
the wires no longer move with the paddle, negating
the possibility of insulation breakdown.
ENUNCIATORS, ALARMS, AND COUNTERS
When a bilge pump runs, you want to know about
it. This can be achieved in one of two ways. The first
and most common method involves installing a pilot
light that is readily visible from the helm. Whenever
complex. (Many who own wood boats wouldn’t dream
of doing without a bilge pump counter.) The simplest
variety is a mechanical digital counter. It looks something
like a mechanical odometer that rolls up by one number
every time the pump cycles on, and it’s reset by pushing
a small lever. If you reset the counter to zero when
leaving the boat, when you return you’ll know how
many times the pump cycled. The only drawback to this
approach is that the counter only tells you how many
times the pump cycled, not how long each cycle lasted.
If the pump ran continuously since you left the boat,
the counter would still read “ 1.” More sophisticated
variations on this theme exist, and, not surprisingly, they
involve digital electronic processors that can monitor
multiple pumps, tell you how many times each pump
ran and for how long, and more. In short, a counter is
a worthwhile addition to any bilge pump system.
If your engine ran out of oil or if carbon monoxide
Left: The height at which a bilge high-water alarm switch is installed can spell the difference between a disaster averted and the loss
of a vessel. Alarm float switches should be installed just high enough to avoid nuisance alarms caused by normal accumulations of
bilgewater—but no higher. Right: The importance of the integrity of a bilge pump’s wiring connections cannot be overstated. All
connections should be located well above normal and extreme accumulation of bilgewater (at least 18 inches above the former). If this
cannot be accomplished, then connections must be truly waterproof. The installation shown here meets neither of these requirements.
the bilge pump operates, regardless of whether it’s
been manually or automatically activated, the light will
illuminate. With this arrangement, if a bilge pump runs
in a manner that’s out of the ordinary (for instance, if
it cycles on every few minutes while you are under
way, which means a raw-water hose may be leaking),
you’ll know it needs to be checked out. A pilot light
enunciator is simple, inexpensive, and effective, and it’s
required if you want to comply with ABYC standards.
The other method of monitoring bilge pump activity
is to use a counter. Bilge pump counters have been
available for ages, and they range from the simple to the
was accumulating in your cabin, you’d want to know
about it, right? That’s why oil pressure alarms and CO
detectors sound an impossible-to-ignore signal, alerting
you to a pending catastrophe. Bilge alarms work in much
the same way, and many people, including me, consider
them to be as vital as bilge pumps themselves. Like bilge
pump counters, bilge alarms range from the simple to
the complex. In their simplest form, a bell or buzzer is
connected to a float switch. When water rises high
enough to trigger the switch, the alarm sounds. More
sophisticated systems are capable of monitoring multiple
bilge compartments. Some include their own power
