Navy: Submarine Skin “Pealing” Mystery Solved

Posted: January 25, 2011 in Uncategorized

The sharkskin-like coating that peeled off early Virginia Class submarines in large swatches appears to be adhering better to newer boats, a top Navy procurement official said.

After the Navy found that the specialized, sonar-absorbing coating had sloughed off three of the first four subs in the class, they initiated an investigation to determine the cause of the problem and how to fix it.

“Clearly we had problems on the early ships,” said Vice Adm. Kevin M. McCoy, commander of Naval Sea Systems Command, the Navy’s ship-buying and maintenance arm. “We think, for the most part, those issues are behind us.”

The loss of the specialized hull coating — designed to be “anechoic,” or able to absorb waves of active sonar so it does not bounce back to the ship or sub emitting the signal — could imperil underway submarines by making them easier to detect.

Despite those problems, McCoy insisted that the hull-coating failures have not contributed to operational issues for the submarines, saying “It’s not been a real big deal for us.”

McCoy said the Navy’s investigation revealed “no single smoking gun,” and that he’s “very confident going forward” that the Navy’s fast-attack submarines will retain the thick black coating that helps keep them silent and stealthy.

Affected submarines are being fixed during their normal dry-dock maintenance periods.

Seven Virginia Class boats are commissioned and at least five more are under construction at Northrop Grumman Corp.’s Newport News shipyard and at General Dynamics Electric Boat in Groton, Conn.

Although Northrop and Electric Boat apply the hull coatings, the Navy specifies the process of application.

The sea service has said it started making procedural changes in how the coating was applied immediately after the first problems surfaced in 2007 on the Virginia, the first sub of the class and the one with the most acute debonding problem to date.

While McCoy declined to reveal the specific of how the process has changed, he said it “has gotten much better improved in terms of temperature controls, humidity controls and adhesion.”

Hull coating failures have been a problem for as long as there have been submarines.

In the past, submarines’ hull coatings were formed by a series of tiles that were glued individually in a patchwork pattern across the entire exterior of a boat, a process that was expensive and time-consuming.

After extended periods of diving underwater and surfacing, the enormous amounts of pressure exerted on the subs by seawater eventually caused several of the tiles to weaken and de-bond.

Starting with the Virginia Class, the Navy scrapped the tile method for a new procedure called “mold-in-place,” in which coating is applied in large swaths, creating a smoother surface. It was thought to be cheaper, faster and more durable.

But early in the program, the coatings tore off underway subs, often in “large sections up to hundreds of square feet,” according to the Pentagon’s top weapons tester.

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