|
Diesel-electric power
has been around for a while, and though it isn’t widely used in
yachts and pleasureboats, it has proven itself as an efficient means of
propulsion in military and research vessels. Advantages such as increased
control, improved fuel efficiency, longer engine life, and lower maintenance
costs have made this hybrid system the power of choice in these fields.
The question facing yacht builders and owners is whether those benefits
outweigh the system’s additional cost.
The idea of using an
engine to power a genset that in turn creates propulsion was initially
used in locomotives and ships by General Electric in the early 20th century,
and in World War I diesel-electric power gained more momentum. U-boats
were some of the first diesel-electric military vessels, but surface ships
also had adopted it by the onset of World War II. Today the U.S. Navy
employs an updated version of diesel-electric power to help fulfill the
demanding electrical requirements of modern warships, as do most cruise
ships and commercial and research vessels.
The concept is simple
enough: engines powering gensets that both provide propulsion via electric
motors and electrical power to a busbar. Thus two formerly independent
functions, propulsion and onboard electrical power, can be controlled
by a single system. In essence, the genset operates the entire boat, from
moving her through the water to flushing the MSDs.
Removing the engines
from the prop shafts has an additional benefit: They can run at optimum
efficiency while shaft revolutions are regulated by variable-speed electric
motors. This increases engine life, since they are never under- or overloaded.
An additional bonus is that by removing the marine gears altogether and
the prop shafts from the engines, you get much quieter propulsion.
Yachts can and do reap
these benefits. Two that currently employ this system are the 414-foot
Octopus and the 315-foot Limitless. Their large sizes are
not coincidental. Ken Robbins, president of Marine Propulsion, says, “When
the energy required to power a ship’s auxiliary systems is equal
to or greater than what it takes to propel it, then diesel-electric is
a logical choice.”
Next page >
Part
2: Because of their complexity, diesel-electric systems are heavy
and take up a lot of space. > Page 1, 2,
3, 4
|