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Naval Warfare

Sea Shadow (IX-529)

Experimental Navy Stealth Demonstrator [ 1985 ]

The Sea Shadow IX-529 boat was a Lockheed stealth product developed for the United States Navy - it operated from 1985 until 2006 before being scrapped.

Authored By: Staff Writer | Last Edited: 07/19/2017 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

The Lockheed company accrued extensive experience when developing their famous F-117 "Night Hawk" stealth fighter which made its public debut in 1991's "Operation Desert Storm". Prior to this, the radar-evading aircraft had seen action in the skies over Grenada and had flown as early as June 1981 - a product of the top-secret "Have Blue" program. The aircraft was built around many radar-evading and absorbing techniques, namely special skin coatings and angular surfaces. Taking this knowledge, Lockheed engineers applied the same concept to a ocean-going vessel and this work begat the "Sea Shadow" (IX-529) - the world's first stealth ship to ever grace the water.

The initial Sea Shadow design was actually intended for submarine tests and involved a cigar-shaped hull covered over in faceted plates. The intent was to limit sonar returns and this ultimately led to the engineers discovering some quite significant results in their work with their submarine model. However, Lockheed had a tough time convincing the Pentagon of the merits of a stealth submarine, particularly one that would prove slower than existing types so the idea gradually evolved into that of a stealth warship which caught the interest of DARPA, the Defense Advanced Research Projects Agency, and a contract was agreed upon between the department and Lockheed's Skunk Works.©MilitaryFactory.com
The Sea Shadow program gained steam in the early 1980s just as the F-117 was beginning to take root in the USAF inventory as the first operational-level stealth aircraft in the world. The Sea Shadow project was another of Lockheed's top secret ventures for the vessel was not unveiled to the public until sometime later, 1993 in fact. The vessel was assembled at Redwood City, California while housed under the "Hughes Mining Barge" (HMB-1), a submersible barge-type craft with integral lifting device - specifically developed to claim the sunken Soviet Navy submarine K-129 which was lost in March of 1968. The mining barge itself was launched in 1974 and eventually underwent modification to become a floating drydock.

The Sea Shadow itself was of a wholly unique look in the world of naval craft. It appeared as though a catamaran design though it was, in fact, a Small Waterplane Area Twin Hull vessel - or "SWATH" - and its hull structure was completely raised out of the water. This approach allowed the craft to have inherently good stability in rough seas and be faster when cutting through the water. The hull utilized the angular approach already witnessed with the blended wing/fuselage approach of the F-117 and its bridge was contoured appropriately at the front of the vessel. A flattened roof line served as a deck of sorts and there were limited protrusions seen along the roof's length. Access hatches were also featured along the roof line. The entire crew complement numbered just four personnel (helmsman, commander, engineer and navigator) as systems automation was another key component of the program.

Trials began in 1981 and it became apparent that the vessel produced too large a wake from its twin propeller units. It was found that these systems had been installed in reverse which, when rectified, led to a large reduction in produced wake from then on. The Sea Shadow only ever managed to be tested and was never pushed into formal evaluation as the Pentagon lost interest in the design. Sea Shadow entered drydock and was not put to sea again though some of its valuable data was later applied to new Navy submarines and warships coming online in the later decade so all was not lost.

The end of the line for Sea Shadow came in 2006 as the United States Navy was still looking for a taker for the experimental ship - none were found through an early attempt at auctioning the hull off. With the price lowered and another auction planned (the sale required the buyer to scrap the vessel and its mining barge in full)m Sea Shadow finally found a taker in Bay Ship & Yacht Company who purchased the $170 million vessel for a mere $2.5 million. The sale was finalized in 2012 and the company adhered to the Navy demand, scrapping Sea Shadow that same year.

The vessel featured prominently in the 007 film "Tomorrow Never Dies" is based on the Sea Shadow and bears a resemblance to the experimental ship.©MilitaryFactory.com
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Service Year

United States national flag graphic
United States


Sea Shadow-class

Sea Shadow (IX-529)

National flag of the United States United States (cancelled)
(OPERATORS list includes past, present, and future operators when applicable)

164.0 ft
49.99 m
68.0 ft
20.73 m
14.0 ft
4.27 m

Installed Power: 2 x Diesel-electric engines.
Surface Speed
14.2 kts
(16.3 mph)

kts = knots | mph = miles-per-hour | nm = nautical miles | mi = miles | km = kilometers

1 kts = 1.15 mph | 1 nm = 1.15 mi | 1 nm = 1.85 km

Supported Types

(Not all weapon types may be represented in the showcase above)

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Images Gallery

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Image of the Sea Shadow (IX-529)
Image from the United States Department of Defense imagery database.
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Image of the Sea Shadow (IX-529)
Image from the United States Department of Defense imagery database.
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Image of the Sea Shadow (IX-529)
Image from the United States Department of Defense imagery database.

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