Page 54: of Maritime Reporter Magazine (April 2000)

Propulsion Performance Products

Is Diesel-Electric Propulsion the System for You?

For the right types of vessels, diesel- among them are: better performance, considerations can enter into play, what electric propulsion offers a myriad of greater cargo capacity, lower costs, and constitutes the "right type of vessel" has advantages over other systems — longer equipment life. Although other largely to do with the difference

The Ultimate in Safety and Efficiency

A model Voith Water Tractor family f, for ship assist and escorting

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Close-up shot of SCR cabinet. between the power required for main propulsion versus what is required for maneuvering: the bigger the disparity, the larger the potential reward.

Supply boats, tugboats, research ves- sels, drill ships, gaming vessels, and in particular, vessels performing dynamic positioning represent prime candidates for a system, which has many experts wondering why it is not employed more extensively. "Diesel-electric has pow- ered the petroleum industry's on- and offshore drilling rigs for decades, is used exclusively in railroad locomotion, and has long been favored by the U.S.

Navy for research and specialty craft," notes naval architect Norman DeJong of DeJong & Lebet Inc., Jacksonville,

Fla. "With an SCR drive, a vessel can go farther, faster, quieter, consume less fuel, carry more cargo, have more maneuverability, reliability, and require less maintenance," he adds.

Synonymous with diesel-electric propulsion, SCR drive takes its name from the silicon-controlled rectifiers —

SCR units — at the heart of the system.

A typical design comprises three or more diesel-powered generators in par- allel, feeding fixed-voltage alternating current to a common switchboard (dia- gram). The switchboard distributes ac to the SCRs, which convert it to vari- able-voltage direct current for the ves- sel's propulsion motors, bowthrusters, 56 Circle 234 on Reader Service Card

Photo of full SCR system.

Maritime Reporter/Engineering News

WARNING' .600 VAC