Keep Water Out—Solar
Vents for Engine Spaces
Of course, there’s one very important proviso
here. You can never have too much air in the
engine room, but you can easily have too
much water! You mustensure that water
can’t find its way below through the vents.
Keeping vent openings fairly high and includ-
ing water traps or baffles is critical.
The designer should detail the vent loca-
tions and duct runs to ensure that the vent
openings are located where they cannot take
on water if the boat is knocked down and
that all compartments are correctly serviced
by a venting system. You can see the basic
vent and duct layout in the drawing of a ferry
my office designed (Figure 16-3).
A final engine-room vent refinement is to
install a solar-powered exhaust vent or two.
These vents are independent of the ship’s
electric system and run whenever the sun is
shining. Thus, even when the boat is unoc-
cupied and unused,its engine room is being
well ventilated. You’ll find a dramatic reduc-
tion in mildew and rust, as well as in any
buildup of unpleasant oil and fuel smells.Generator Vent Requirements
Vent requirements for sailboats and motor-
sailers are exactly the same—an engine is an
engine. Remember also to include the total
power of all machinery installed in the engine
room, including gen sets and compressors.
If you don’t have the generator’s spec
sheet, you can estimate a generator’s engine
power from Formula 16-4.Formula 16-4. Approximate Generator
Engine PowerFull-Load Gen-Set Engine bhp= 1.7×
max. rated electric kW outputorFull-Load Gen-Set Engine kW= 1.27×
max. rated electric kW outputIfAfter Burnerhad a 12 kW generator in
the engine compartment, you would add
20 hp or 15 kW for its engine when determin-
ing total vent requirements.PART FIVE:VENTILATION, AIR-CONDITIONING, AND HEATING
Figure 16-2. Large
axial blower in
engine room
Formula 16-4.