Traditional bilge pump float switches are inexpensive and are usually reliable when working in clean bilges under moderate operating conditions. However they can be troublesome in messy bilges where the float can hang up or pump large amounts of spilled oil overboard. Their lightweight mechanical construction also can cause trouble for boats operating in rough, jarring seas.

My 295 Boston Whaler Conquest operates as a Coast Guard Auxiliary SAR vessel on Long Island Sound—a body of water that can produce nasty short-period, four-foot sees that will rattle your teeth and beat plastic mechanical switches into submission. Replacing the mechanical float switch in my boat’s bilge has become an annual event.

This year, I decided to take a new approach to the bilge switch challenge. After a bit of research, I installed a Water Witch Model 101 electronic bilge pump switch—an electronic device that has no moving parts and is the newest member of a family of water sensors widely used by commercial and government agencies whose boats operate in the toughest environments.

The accompanying photo shows the installation in my boat. The black “box” is a potted circuit board. The coin sized button and the metal attaching tab are both sensors. If you look closely, the switch has three wires (red, brown and black) as compared with the two wires found on traditional switches.

Installation is simple. The red and brown wires are hooked up to your bilge pump just like a traditional float switch. The black wire goes to any DC ground, typically the ground connection at the pump itself.

The switch can be mounted in any position. In our installation, we simply strapped the mounting tab to the pump itself. However, we could have mounted it remotely.

We have tested the pump under all sorts of conditions and found that it works flawlessly. We also repeated the “oily bilge” experiment shown on the Water Witch web site and enjoyed the same positive results. The switch will not pump hydrocarbons so you don’t have to worry about heavy concentration of oil in the bilge being pumped overboard.

Water Witch manufacturers a full line of electronic water sensing systems including instrument panel indicators that will show you when and how often your bilge pumps are running. The company also makes high-water sensors. One of the more interesting applications is in Coast Guard rescue boats where the switches are mounted on the cockpit overheads. The switch operates a radio alerting system should the boat capsize and not right itself immediately.

We’ll keep you posted on our experience with the Model 101. You can find the switch at most outlets priced at about $30. The Model 101 float switch replacement module requires 12-volt DC and draws 4 mA at rest. It can handle a maximum pump load of 15 amps.

Information on Water Witch bilge systems and installation help is available through its web at www.waterwitchinc.com.