Buyers Guide to Bilge Alarms
Bilge alarms or “high water” alarms are required by the U.S. Coast Guard on boats over 26’ long, but are rarely seen on smaller boats. This is an omission that can cost you your boat—if you have enclosed bilges where water coming aboard is not immediately visible, a bilge alarm is a wise investment, even if it’s not required equipment.
And if your boat has a bilge alarm already, now is a good time hit that “Test” button and make sure it’s functional. If not, check here for a replacement.
If you have a catamaran design, remember you need at least one alarm in each hull. And for boats with multiple compartments at the bilge level, a sensor in each compartment is a good idea.
The bilge alarm lets you know well in advance of the point that things get critical that there’s more water in the bottom of your boat than there should be, and that you’d better take a look post-haste at your bilge pump and float valve if you want to stay afloat.
Water most often gets inside the boat through faulty through-hull fittings and hoses supplying water to the engine heat exchanger, air-conditioning system or watermaker, and these often develop slowly, so the alarm system gives you plenty of time to find and fix the problem. Of course, if the hull gets holed you’ll usually know it immediately, but just in case, the alarm comes in again.
Conventional bilge alarms have audible and visible alarms on the console or in the cabins to alert you while you’re on the boat. They’re inexpensive and (except for pushing the wires) easy to install. If you own a boat with an enclosed bilge, it really should have at least one of these basic alarms.
Bilge alarms that can link to your cell phone are more expensive, but also more useful because they will alert you to water rising inside the boat where ever you happen to be. These require a monthly service fee in addition to the cost of the unit, but are well worth it for peace of mind when you’re not aboard.
On larger boats, the bilge alarm’s audible warning should be loud enough and near enough to sleeping quarters to wake up captain and crew. Leaks don’t always occur when there’s someone at the helm.
Sensors are typically mounted on a bulkhead, stringer, inner transom or hull of the boat above the normal operating level of the automatic float switch for the bilge pump, but below the level of critical components of your boat and/or engine, such as the starter. If water covers the sensor for more than a few seconds the system is triggered and sends the alarm signal.
Aqualarm offers both conventional and cellular high water alarms. The cellular model has both a local alarm that registers on the dash module and a transmitter that links to a cell phone and email, alerting the owner to leaks while away from the boat. The cellular connection has a monthly service fee, currently $9.50. Price is about $390; https://aqualarm.net.
Johnson Pump High Water Alarm includes a sensor which is totally sealed and has no moving parts, assuring long, dependable service. The small size of the sensor allows it to be mounted in tight confines. If water disrupts the sensor for more than 8 seconds the alarm and warning LED will be triggered. The alarm is puts out 100 dB, assuring it will be heard throughout the typical recreational boat. It’s about $100; Johnson Pump.
Rule-A-Matic Water Alarm includes a float switch hard-wired to a dash alert module. Anytime it’s activated, the float switch turns on the bilge pump and triggers both visible and audible (85 dB) alarms. It’s about $80. Rule is also one of the best-known makers of bilge pumps and float switches; Defender.com.
Safe-T-Alert high water alarm includes a test button to assure the system is working and also a muting system to shut off the noise when you go below to check on the problem. The company says it will not give false alarms from water slopping in the bilge, rain or other minor water intrusions. It’s about $45 including the sensor; https://www.mtiindustries.com.
The Siren Wireless High-Water Sensor detects if there is water in the bilge and instantly sends an alert to the Siren Marine App if water has risen above a preset level. You mount the water probe at the desired height in the bilge and plug the other end into the wireless module. Link the module to the Siren 3 Pro Connected Boat system (with a monthly fee) and your phone receives alerts if the boat is taking on water. It’s about $130; https://sirenmarine.com.