to electricity. (Every conversion from one
type of energy to another involves losses.) If
you are not aboard to run the engine, though,
there is no way to keep the icebox cool. This
is a problem if—on a cruise—you leave the
boat at anchor for two or three days to ex-
plore on land. The food in the fridge will go
bad.
For this reason, I generally recommend
12- or 24-volt DC power for these systems. If
you are careful to top up your batteries, you
can leave for several days and the unit will
continue to cycle on and off as needed to
keep things cool. The 120-volt AC power
option enables you to plug these systems in
at the dock.Water-Cooled Heat
Exchangers
Another reason household-style fridges are
less efficient is that they are air cooled. The
heat-exchanger coil on the fridge simply
dumps the heat pumped out of the box into
the surrounding cabin air. As we saw withair-conditioners, the more efficient way to
expel unwanted heat is through a seawater
heat exchanger. For either the icebox conver-
sions or the holding-plate systems—though
air-cooled units are available—I recommend
you go only with seawater heat-exchangers.CABIN HEATING
With good ventilation, air-conditioning and re-
frigeration can be considered optional. Both
enhance comfort, but sailors have voyaged
the globe without either for centuries. Heat is
another matter. Without some form of heat,
boats can be brutally uncomfortable in cold
weather—even deadly. Protracted cold leads
to fatigue, poor judgment, and even real dan-
ger from hypothermia. There are just seven
standard options for cabin heating:1 .Old-time coal or wood stoves and
fireplaces
2 .Reverse-cycle air-conditioning
3 .Direct electric cabin heatingPART FIVE: VENTILATION, AIR-CONDITIONING, AND HEATING
Figure 15-5.
Engine-driven
holding-plate
refrigeration. If
this were a 12-volt
system the com-
pressor would be
driven off a 12-volt
motor. (Courtesy
Taylor Made
Environmental/
Grunert)