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The Next Big Thing

The Next Big Thing

Is diesel-electric power finally going to get its day in the sun?

January 2005

   
 More of this Feature

• Part 1: Diesel-Electric
• Part 2: Diesel-Electric
• Part 3: Diesel-Electric
• Diesel-Electric For Smaller Craft?

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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

This article originally appeared in the January 2005 issue of Power & Motoryacht magazine.

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