Hi all,
High water alarms are, to me, essential safety equipment and are an essential early warning system much like smoke detectors. Both, to my mind, should be built into the design of the boat and installed at the factory level. As a consequence, most of us are installing these important alarms on our own. Both, give a bit of room for the skipper and crew to find the problem: without that early warning, it is often too late to find the leak (because the higher water hides the leak) or to have any chance to fight a blossoming fire.
Well before I ever noticed “marine” high water alarms on the market, I started using household sump alarms and still do. The advantages I appreciate (besides being a fraction of the cost) is that they are a compact unit self-powered with a 9v battery (beeps like a smoke detector when low on power: never happened to me when a new battery starts each season).
Installation is made easier as there is no electrical connection to the vessel’s power grid. The sensor dangles on a cord making height placement easy to adjust (the alarm is silenced merely by lifting the sensor out of the water) and allowing some latitude in placing the control box where the alarm sound comes from.
Considerations:
The alarm must be loud enough to alert people wherever they are on the boat with the motor running (making silencing the alarm even more of a blessing).
I place my alarm height pretty low as I have a pretty dry boat so I wish to know whenever water begins to collect. The sensor is below the height my bilge pumps are activated, which are also alarmed. The sensor is attached to a dowel that can be lifted out easily
Testing the alarm is easy as I just monthly drop the sensor in a cup of water.
I have a bilge area dedicated to the stern of the boat where I have a second high water alarm. If I did not, I might consider building a dam and alarm that area as, over the years, this area’s alarm has flagged a number of problems well before they became “real” problems: leaking coolant, failing seal on the rudder shaft, cracked raw water hose, piece of debris in between the faces of my dripless shaft seal, and the like.
My best, Dick Stevenson, s/v Alch