Installing a Bilge Heater
Fight the common cold snap on your boat with a bilge heater.
by Steve Noury
February 1, 2005
With the cold months here, it's always a good idea to make sure your boat/engine is properly
prepared for the lower temperatures and long periods of idle time. One of the best ways to prevent
larger boats with inboard or sterndrive engines from 'freezing up' during the winter months is to
install a heater in the bilge or engine compartment area.
Step 1 - A heater manufactured by Boatsafe, model BSAT-750W (Bensaco Inc.,
www.boatsafeheaters.com) is used in this article. The
first order of business is to select the right wattage heater for your size boat. Most
manufacturers will make several models to accommodate almost any size boat. The next thing you want
to do is decide exactly where to put the heater within the bilge or engine compartment. The
tendency is to put it in the lowest spot you can find (heat rises), but you want to be sure, at
some point, it's not going to be sitting in any water. In this example, the heater is installed on
a 30-foot Sea Ray with twin engines, and there is a fair amount of room to work with. There are two
'stringers' at the bottom of the compartment that are about 8 inches apart and run parallel to the
length of the boat. It's a perfect place to mount the heater!
Step 2 - It may be a perfect place to install the heater, but you need some help
in keeping the whole operation intact. In order to ensure the stability of the bilge heater you're
installing on your boat, you should first secure a sturdy 2-foot-8-inch wooden board (which is the
exact length of the bilge heater), perpendicular and across both of the stringers in the engine
compartment. The tools you need for this part of the installation are four 2-inch stainless-steel
screws and a power drill to secure the board to the stringers. The wooden board has to be set
slightly off-center in order to stay clear of several seacock shut-off valves in and around the
engine compartment. Once the wooden board is down, use 4-inch screws to attach the heater to the
board for a sturdy fit inside the compartment.
Step 3 - With the bilge heater firmly in place on the wooden board, run the power
cord for the heater through the compartment to a corner in the rear of the boat. Using cable ties
for this, make sure it's nice and secure, out of the way, and not touching anything that may get
too hot when the engine is running. In the rear corner of the boat, drill a hole (out-of-sight,
under the lip of the engine compartment hatch), pull the power cord through the hole, and then run
it out of the back of the boat through a drainage slot in the deck. The power cord for this
particular product is plenty long enough to reach the shore-power socket located at the front of
the slip, where the boat is docked during the time of the installation.
Step 4 - The last step is to test the bilge heater to make sure it works properly.
If the air temperature is not below 45 degrees Fahrenheit, then you must simulate an ambient below
that temperature. To create that simulation, plug the heater into the power source, and locate the
small hole marked 'Test' on the end-cover of the unit. Using the supplied Freeze Mist spray can,
insert the straw-tube into the nozzle, and spray a 2- to 3-second burst of mist into the 'Test'
hole. This will trick the thermostat into turning on the heater. In normal operating conditions,
the thermostat will turn on the heater when the temperature is below 45 degrees, and it will turn
it off when the temperature gets above 55 degrees.