Much of the rationale for designing and building all-aluminum ships for the U.S. Navy stems from a paper delivered to the Society of Naval Architects and Marine Engineers in 2009.
Entitled The Benefits and Cost Impact of Aluminum Naval Ship Structure, the paper by naval architects Thomas Lamb, Nathaniel Beavers, Thomas Ingram and Anton Schmieman argued that "even though the cost of the aluminum structure is over 40 percent more than the steel structure, an 'equivalent' aluminum naval ship can be built within 7.5 percent of the acquisition price of a steel ship. This is possible because of the cascading benefits of the aluminum ship's significantly lighter weight. Aluminum ships also have a lifecycle cost advantage over steel ships because of reduced maintenance and fuel cost savings."
The research team—headed by Lamb, emeritus research scientist and adjunct professor in the School of Naval Architecture and Marine Engineering at the University of Michigan, and Beavers, of the Alcoa Technical Center—argued that "the aluminum equivalent ship will have a lower total ownership cost."
The authors pointed out that the weight savings in a typical small naval frigate built of aluminum would result in fuel savings of approximately 71 tons per voyage. Over the typical 25-year life of such a naval vessel, fuel cost savings would be in the neighborhood of $32 million. And because aluminum vessels don't need to be painted, the $500,000 cost of painting a small frigate every five years would save another $2 million to $3 million over the life of the ship, they said.
"When these potential benefits are extended to a fleet of 10 ships, the fuel savings would be $320 million and the maintenance saving $25 million. This will become even more important if the fuel supply diminishes and the price of fuel for the ships increase," the authors said.
There are more than 430 shipyards around the world with the capability to build and repair aluminum ships, including 44 shipyards and repair facilities in the United States, the paper said, and as those shipyards become more proficient with new technologies, such as friction stir welding of extruded aluminum panels, they inevitably will become even more competitive with yards that build steel ships. BILL BECK