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Aluminum

Versatile vessel

By Nick Wright

Alcoa supplies marine aluminum for Navy’s combat ship program

April 2012 - This past January in Mobile, Ala., one of the single largest uses of aluminum in the world was christened into service with traditional pomp and the smash of a champagne bottle. As the second ship of the Independence-class, 12-vessel Littoral Combat Ship (LCS) program, the USS Coronado is designed to be responsive and nimble in shallower shoreline areas.

The agile, 127-meter (about 416 feet) vessel is constructed from aluminum, much of which Alcoa Inc., Pittsburgh, supplied. Hundreds of thousands of pounds of Alcoa’s 5083 alloy, an aluminum grade resistant to extreme environments like saltwater, make up the ship’s hull. An Alcoa press release indicates the USS Coronado features a trimaran hull, a design that offers stability, endurance, shallow draft and a flight deck larger than any other Navy surface combatant. The maneuverable ship has a maximum speed of more than 45 knots (approximately 50 mph).

The 5083 alloy allows for the ship to be lighter, stronger and faster, says Kevin Lowery, director of communications for Alcoa’s global rolled products. Such characteristics are necessary for operations in the littoral zone, which the Office of Naval Research defines as waters between the shore and up to 600 feet out into the water.

“[Aluminum] is an enabler for many of the other aspects of the ship,” Lowery says. “Because it is lighter than steel yet has the same if not better performance in terms of strength and durability, it allows the ship to improve its speed, maneuverability and agility while still protecting people.”

Alcoa Defense, the branch of Alcoa that fabricates aluminum for military applications, produced the marine aluminum plate for defense contractor Austal USA, Mobile, Ala. Austal specializes in custom aluminum vessels for defense and commercial uses.

“Austal selected Alcoa aluminum for this critical supply contract for many reasons, including our unmatched dimensional capabilities of our rolling mills—delivering the widest range of sizes available in the industry,” said David Dobson, president of Alcoa Defense, in a press release. “Alcoa and Austal are working together to introduce innovative flight-deck tie downs, aluminum armor solutions and large, thick plate sub-assemblies to subsequent LCS vessels that will take even more weight off the ship and improve shipbuilding efficiency.”

According to Alcoa, the company’s Davenport Works in Riverdale, Iowa, shipped the aluminum. “In total, there’s about 1 million pounds per ship,” Lowery says.

Modular defenses
Designated as LCS 4, the USS Coronado and other LCS ships can be outfitted with reconfigurable payloads called mission packages, that can be switched quickly depending on the need, such as mine countermeasure, anti-submarine and surface warfare, according to a Navy press release. The mission packages are supported by special detachments that deploy manned or unmanned vehicles and sensors.

Along with marine plate, Alcoa Defense also supplies fabricated aluminum subassemblies for the Austal LCS.

“We believe in the right material for the right application,” Lowery says. “Through our alloy development work, we’ve created alloys that meet the conditions found on the moon to underwater. So we’ve developed alloys that don’t corrode.”

Alcoa Defense and the Davenport facility are providing Austal with high-quality aluminum for the Joint High Speed Vessel (JHSV) program, another Navy endeavor, in addition to the LCS program.

“They are two very different ships with very different mission requirements,” Lowery adds.

According to the Navy, which has a sizable presence in Coronado, Calif., the LCS is the third ship to be named for the San Diego-area city. This continues the practice of naming the agile LCS vessels after American mid-sized cities and communities. However, the next LCS to be built may be bucking tradition for perhaps an equally honorable recognition: The Navy announced in February that the LCS 10 will be named for former Arizona congresswoman Gabrielle Giffords. MM

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