Disappearing Act

All Hands, March 2001

Ever get that feeling of dj vu? Every now and then, San Diego Sailors and civilians get that same feeling when they look out into the bay and get a glimpse of what they think they just saw on that last episode of "Deep Space Nine" or one of those James Bond flicks. On the contrary, they are looking at one of the coolest technological advances the Navy has made, Sea Shadow (IX 529).

In fact, Sea Shadow has been around since the mid-1980s. Built in total secrecy from parts made at many different factories, it was classified up until April 1993 when it was announced to the world as a test craft owned by the Navy. Its sole purpose is to explore a variety of new technologies for surface ships, including ship control, structures, automation for reduced manning, seakeeping and signature control, or stealth.

"That's basically the ability to limit how observable our signatures are to enemy sensors," said Darrell Griffin, the Lockheed Martin contract manager of Sea Shadow operations for Naval Sea Systems Command. "Ideally, a threat won't detect us. But, even if they do, stealth features make it difficult to identify, target and engage us with a weapon."

A very unique looking vessel, to say the least, with its hard angles and clear resemblance to a floating version of the Air Force F-117, this ship is a genesis for the future of naval vessels. A side view reveals a long, sloping trapezoid, which quickly changes to a large, floating letter "A" as it turns to the front.

Of course, stealth at sea requires much more than just reducing a ship's radar cross section. Sonar and infrared sensors can be equally threatening, so the approach to designing a stealthy ship demands that all signatures be reduced and managed in a balanced way.

One of the ways that Sea Shadow addresses signature control is with a unique hull design. The two thin struts that support its main deck structure stand on a pair of submerged, submarine-like pontoons in what is known as a Small Water plane Area Twin Hull (SWATH) configuration.

SWATH designs have long been known for exceptional stability in heavy seas, and in the case of Sea Shadow, they allowed the designers to slope the vessel's sides inward at an extreme angle, aiding the stealth characteristics.

Normally, a ship's sides are nearly vertical and meet the water at close to a 90 degree angle. This produces a bright radar echo called a broadside flash, which is easy to home in on. Newer ship designs, starting with the Arleigh Burke-class destroyers, feature sloped hulls, although the slope is less extreme than in Sea Shadow.

After a lull in its use for about five years, the Navy reactivated Sea Shadow as a test platform to research future ship engineering concepts and to serve as a host vessel for companies to demonstrate advanced naval technologies. Sea Shadow's return to service began with a flourish at the Navy's Fleet Battle Experiment Echo in March 1999, where the ship played the role of an adversary by supporting Special Warfare teams and simulating missile attacks against Navy vessels. "The debut for reactivation of Sea Shadow was during Exercise Urban Warrior in 1999," said Griffin. "We also just participated in Fleet Battle Experiment Hotel to look at new warfare scenarios using Sea Shadow."

As a result, newer tests have led to the design concepts of the new DD 21 Zumwalt-class Land Attack Destroyer, which will replace the DD 963 and FFG 7 classes of destroyer and frigate in today's naval inventory. DD 21's primary mission will be land attack support for ground forces. Armed with a new advanced gun system and extended range guided munitions, the ship will provide naval gunfire support at a high rate of fire up to 100 miles inland.

The first of these 95-man Zumwalt-class destroyers (vice traditional crew size of 440) is due to be commissioned in 2008.

As Sea Shadow continues to test innovations at sea for the benefit of other classes of future ships, she may or may not be seen navigating San Diego's harbor. It's not dj vu or some elaborate magic trick, but rather a high-tech research project that will make naval vessels safer for the Sailors of tomorrow.

Story and photos by PH2 Aaron Ansarov, a photojournalist assigned to All Hands.