Boating and Sailing.pdf - Moja ladja

the top of the cylinder then shoots in a small
amount of fuel, generally kerosene-like light
oils, and the heat ignites it immediately. The
power and exhaust strokes are like that of gasoline
four-cycles.
Diesels burn less expensive fuel than gasoline
engines, and they burn it more efficiently. They
must be built heavier than gas engines due to the
forces of compression, but they last longer—in
fact, a well-maintained diesel may outlive three or
four gasoline engines before requiring a major
rebuild.
Fuel Economy
Chapter 2: Power to the People—Marine Engines
Boat Bytes
Diesels are available in
power to more than 1,200
horses, which makes them
the only reasonable choice
for large yachts. Very small
diesels of 50 horses or less are
sometimes the engines fitted to
ocean-going trawlers because of
their extreme stinginess with
fuel—there are no fuel docks in
the middle of the Pacific Ocean!
Diesels like this Caterpillar
are available in sizes large
enough to power even 200foot
yachts. They’re heavy
but very durable, normally
outliving gasoline engines.
(Photo credit: Caterpillar
Corporation)
Gasoline two-cycle outboards put out about 10 horses per gallon of fuel burned at full
throttle. For example, a 200-horse motor will consume somewhere near 20 gallons an
hour, while a 150-horse motor will eat somewhere around 15 gallons an hour. It’s not
uncommon for motors to be a couple of gallons over on this, with a 150 taking, say, 18
gallons an hour at 5,800 rpms. Four-cycle outboards can cut this fuel use up to 60 percent
in the mid-ranges, though they use nearly as
much as two-cycles at full speed.
Boater-ese
Top-End Performance
While all gasoline motors of a given horsepower
are similar in top speed at maximum rpms, they’re
not the same. Some do better on fuel and still
Rpms, or revolutions per
minute, refers to the number of
times an engine’s output shaft
rotates in 60 seconds.
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