4 .Diesel or kerosene bulkhead heaters
5 .Engine-heat heaters
6 .Diesel-fired hot-air heaters
7 .Diesel-fired hot-water heaters
(hydronic heaters)An eighth option is cabin heaters powered
by propane (LPG). These can operate exactly
the same as options 4, 6, and 7. There are
liquefied petroleum gas (LPG) heating
systems manufactured specifically for and
installed on boats, but I recommend against
this. Though it’s perfectly OK for cooking,
relying on the large amount of LPG needed
for long-term onboard heating is too risky in
my opinion. In addition, the heat energy in
LPG is notably less per unit volume and per
unit weight than diesel. Further, you’ll need
two sources of fuel aboard rather than just
diesel, and finding the larger LPG tanks
required is not easy, particularly within a
manageable walk from most marinas or fuel
docks. If you do install an LPG/propane cabin
heater, you must rigorously follow allthe rec-
ommendations of ABYC, NFPA 302, and the
CFR.Wood and Coal Stoves
and Heaters
In the old days, of course, boats relied on
simple coal or wood stoves and heaters for
both cooking and heating. I have fond memo-
ries of the Shipmate Skippy cabin heater
(Figure 15-6). This little wood and coal stove
produced prodigious quantities of heat for its
diminutive size, just 19 inches wide, 13^1 / 4 inches
high, and 14inches deep (48 by 34 by 35 cm).Chapter 15: Air-Conditioning and Heating
Insulation for Fridges
and Freezers
Standard insulation materials for built-in
refrigerators and freezers are foams such
as pour-in-place polystyrene, urethane, or
isocyanate board. They all work by en-
capsulating bubbles of entrapped air. The
efficiency of insulation (its resistance to
transmitting heat energy) is measured as
itsR-value. All these standard foam insula-
tions have R-values approximated as fol-
lows for a given thickness:
Thickness
In. mm R-Value
37515
4 100 20
5 125 25
6 150 30
The minimum thickness for built-in fridges
is 3 inches (75 mm), with 4 inches (100 mm)
or more being optimal. The minimum
thickness for built-in freezers is 4 inches
(100 mm), with 5 inches (125 mm) or more
being optimal. The problem here is obvi-
ous. After allowing for the structure of the
box itself and then adding the insulation
and watertight interior liner (usually
fiberglass or wood/epoxy), a tremendous
amount of volume is lost to insulation. A
relatively new development is Dow
Chemical’s VacuPanel. These are avail-
able as 1-inch-thick (25 mm) panels with
an incredible R-value of 75. This is equal
to 15 inches (380 mm) of standard foam!
The drawback to VacuPanel is that it is
rigid and cannot be shaped. You must
build the box around the flat regular
shapes that the VacuPanel comes in.
Figure 15-6.
Shipmate Skippy
cabin heater
(Courtesy
Shipmate Stove
Co.)