Stealth at Sea

Navy Stealthy About Details Of 'Sea Shadow'

By David Abel  |  Defense Week  |  8/2/1999

If you could see it slipping silently through the sea, you might glimpse something at first that looked like a barreling barge.

As it came closer, and you watched the sloping hull slice through the surf, noticed the beveled bow and the silvery slits peeking through the black, you might think you were seeing the vaunted F-117A stealth fighter skating on the sea.

That's if you could see it. But unless you eyeballed it, it's unlikely you would ever see what the Naval Sea Systems Command calls "the world's most advanced surface ship."

That's because the stealthy Sea Shadow-built secretly in the early 1980s by the Navy, the Defense Advanced Research Projects Agency and Lockheed Martin Missiles & Space Co.-is said to evade sonar, radar and infrared sensors.

The program came out of the black in 1993, but was in mothballs until February. The Navy now says the ship will be used to test various technologies for the next-generation DD-21 destroyer. But program officials are guarded about what else the ship might do.

In an interview with Defense Week, Paul Chatterton, the Sea Shadow program manager, carefully avoided disclosing too many details about the $50 million ship and its current operations.

This is all he'll say about its current mission: "There is no difference in the mission from the early 1980s. Sea Shadow was built originally as a test platform only to look at a list of different technologies: structure, automation, reduced manning and signature control. It's purpose today is still to go out and do research and development in those areas. It's never been intended to be an operational Navy ship."

These are some of the questions Chatterton, a 15- year veteran of the program, won't answer: What's been learned so far?

"I won't discuss results."

What kind of tests have been done?

"No, can't get into that."

What's the operating budget? "Can't discuss that," though he did say the program has spent $195 million since the ship went into service.
Other questions too sensitive to discuss: Is it still being used to test stealth technology?

"Again, I don't want to get into details."

Does it carry weapons? "Don't want to get into that."

Will the ship be used to test a combat identification system and a "tactical action advisor" system that monitors threats to the ship, two applications mentioned on Lockheed Martin's homepage?

"There was some work done in 1993," he said. "That's as far as I'm going to go."

What is known
What Chatterton and a Navy brochure do say about Sea Shadow: The ship has a maximum speed of 14 knots, a range of 1,000 nautical miles, holds up to 12 people, operates with a special diesel-electric propulsion system and extends bow-to-stern 164 feet.

Sea Shadow glides above the water on two thin struts attached to a pair of submerged, torpedo-like pontoons in what is known as the Small Waterplane Area Twin Hull (SWATH). 
The goal of SWATH is to add stability to the ship, reduce its wake to a negligible trail and minimize noise by raising its engine out of the water, according to published articles.

Sea Shadow was built sometime in the early 1980s and assembled inside a huge mining barge at a port in Redwood City, Calif. But the Navy, unconvinced of its relative value in the context of a tight budget, mothballed the ship in 1986. Between 1986 and last February, the ship was only active for two years- between 1992 and 1994.

Not much is known publicly about its current operations. Some speculate the Navy may also be using Sea Shadow to study ways of attacking other stealth ships.

The applications
Chatterton wouldn't say much about what technology proved on Sea Shadow has been applied to other Navy ships. But he acknowledged the SWATH design has been applied to the Navy's TAGOS ocean surveillance ships, and Arleigh Burke-class destroyers have used sloped instead of vertical bulk heads to increase their stealth.

When asked whether the tests carried out on Sea Shadow could be done as well on other ships, Chatterton said in some cases they could.

"It's a question of cost and availability and impact on the fleet asset," he said. "Sea Shadow, just by its size, is cheaper to operate and certainly doesn't have an impact on a Navy asset."

Does Sea Shadow's future hold more mothballs?

All he would say is this: "It's a matter of what testing is needed to support what programs."

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