TECHNICAL DEVELOPMENTS
The cruise industry has shown itself more ready than many sectors of the marine industry to embrace new technology, such as diesel electric power generation, podded drives and, most recently gas turbines.

Realistically, the driver behind all this is plain, old-fashioned capitalistic cupidity. All these technologies free up space on board ship that can be used to generate revenues. A more recent spur to technical innovation has been environmental concerns—or, more bluntly, fear of being locked out of environmentally sensitive, but highly profitable, cruising areas such as Alaska.

So far as supplying prime movers for oceangoing ships is concerned, today’s diesel market is pretty much a two-horse (or perhaps a two-stable) race. Currently, one stable, Wärtsilä, is fielding the “enviro engine” and the other, MAN B&W, the invisible smoke “IS” engine.

Technically, there is no doubt at all that diesel engines can be made considerably less polluting. The only questions to be answered center on what sort of cost penalties owners are prepared to pay to achieve greeness. At some point, it can be argued that the gas turbine then becomes competitive with the diesel in terms of fuel cost—particularly if you throw an exhaust-heat-powered steam turbine into the picture.

GAS TURBINE COMPETITION
Thus far GE has dominated the market for cruise ship gas turbines, but now it is to get some competition. MAN B&W Diesel and MAN GHH Borsig have jointly announced that they will offer CODAG (combined Diesel Engine and Gas Turbine Electric) propulsion systems for cruise ship applications.

Both types of prime mover—diesels and gas turbines—drive generators in the CODAG arrangement, delivering the electrical power required for ship propulsion and hotel load. The CODAG system combines the advantages of the two engine types, giving high efficiency and high energy density and reducing weight and space requirements.

While MAN B&W Diesel will be familiar to readers, they may be less familiar with MAN GHH Borsig. Also a member of the MAN Group, it has considerable experience in packaging FT8 gas turbines in mechanical and generator drive applications. The FT8 is an aeroderivative of the popular and well-proven Pratt & Whitney JT8D, which has millions of operating hours to date.

Various propulsion configurations are being offered to meet specific customer requirements in the 30-120 MW range. The diesel elements of the packages are available with MAN B&W’s IS (invisible smoke) option, permitting an effective suppression of soot formation without exceeding the visible soot limit.

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