DDG-31 Decatur
EDDG-31 Self Defense Test Ship (SDTS)

Originally ships of the Forrest Sherman (DD-931) and Mitscher classes, six ships were rebuilt and reclassified as guided missile destroyers in 1966 and 1967. The planned 18 month conversion of the Turner Joy was cancelled. They have all been removed from service. Although stricken in 1988, the ship which has been used since 1993 as EDDG-31 Self Defense Test Ship (SDTS). Commonly referred to as "ex-Decatur", the ship is moored at the Engineering Field Activity, West, Naval Facilities Engineering Command, San Bruno, CA.

The Forrest Sherman class destroyers were the first US destroyers of post-World War II design and construction. The entire superstructure of these ships were of aluminum to obtain maximum stability with minimum displacement. All living spaces were air conditioned. With one gun forward and two aft, these were the first US warships with more firepower aft than forward. They all subsequently had their anti-submarine capabilities improved.

The ASW Modernization Program started with eight DD-931/945 Class ships being programmed for overhaul and modernization at the Charleston and Boston Naval Shipyards. Long lead time material was ordered, however the whole program had to be deferred due to higher priority con:nnitments in Southeast Asia. Later the decision was made to conduct the modernizations at Bath, Maine in a private shipyard. Even though more long lead time material had been ordered, high costs caused the program to again be deferred.

Finally the decision was made to have the Philadelphia Naval Shipyard handle the program, and again more material was ordered. In early 1969, due to the workload at the Philadelphia Naval Shipyard being too heavy to complete the ships within the programmed time frame, the decision was made to reallocate two ships to Boston Naval Shipyard, two to Long Beach Naval Shipyard, let three remain at Philadelphia and drop one completely (due to high costs). While the start/stop decisions were being made, the individual ships originally shceduled for the program were continuously changed as time went on.

The Guided Missile Destroyer Decatur (DDG 73) was christened on Saturday, November 9, 1996, at Bath Iron Works, Bath, Maine. The ship is named in honor of Commodore Stephen Decatur (1779-1820), famed for his raid to burn the captured U.S. frigate Philadelphia in Tripoli harbor in 1804. He later served with honor in command of the frigates USS United States and USS President during the War of 1812. Four previous ships were named in his honor, a sloop-of-war and three destroyers spanning the period from 1840 to 1983. The third Decatur (DD 341) earned two battle stars in World War II; the fourth (DDG 31) earned eight battle stars in Vietnam. The Navy felt that the newer ships in the fleet could do the job of the Forrest Sherman/DDG-31 class more efficiently.

One of the Naval Sea Systems Command's more unique test assets is the EDDG-31 Self Defense Test Ship (SDTS). The Self Defense Test Ship is the ex-USS Decatur (ex-DD 936, DDG-31), a decommissioned ship that has been supporting various naval test and evaluation operations since October of 1994. The test ship is a unique asset to the Navy and its mission is to support the entire spectrum of integrated self defense systems engineering, test, and evaluation. Designed for unmanned operations on the Point Mugu Sea Test Range, the test ship can be remotely piloted from Point Mugu's Naval Air Warfare Center Weapons Division with combat systems operated from the Surface Warfare Engineering Facility Complex.

The Self Defense Test Ship (SDTS) is a Navy asset located at NAVSEA Port Hueneme. The SDTS is a refurbished, remote-controlled ship. The ship supports self-defense engineering, test, and evaluation, without the safety constraints and in-port problems that are associated with manned ships. During typical operations, launched threats attack the SDTS and the combat or weapon system being tested responds to these threats in defense of the ship. The predetermined attack is actually aimed at a decoy barge pulled 150 feet behind the test ship to protect the ship and its assets.

Some systems installed on the SDTS include MK 57 NATO Seasparrow, MK 23 Target Acquisition system, Rolling Airframe Missile, AN/SLQ32 (v) 3 ESM, and Close-in-Weapon System. The SDTS team received Vice President Al Gore's Hammer Award in special recognition of significant government efficiencies. The SDTS won the award for providing the Navy with a cost-effective test platform for its combat, weapon, and missile systems. In addition, the SDTS received local acknowledgment by earning a Certificate of Recognition for the Ventura County/Santa Barbara County Engineering Project of the Year Award.

The principal air threat to U.S. naval surface ships is a variety of highly capable Anti-Ship Cruise Missiles (ASCMs). With radars and anti-air weapons for self-defense of today's amphibious ships and aircraft carriers installed as standalone systems, considerable manual intervention is required to complete the detect to engage sequence against ASCMs. The Ship Self Defense System (SSDS) is designed to expedite that process. FOT&E of Mark 1 was conducted onboard the remotely controlled Self Defense Test Ship during FY99 at the Naval Air Warfare Center, Weapons Division Sea Range at Point Mugu, CA.

The Block 1 variant of the Rolling Airframe Missile (RAM) achieved a warhead kill against an Exocet anti-ship missile during developmental testing on 12 December 1998. The flight test exercise was conducted from the Self-Defense Test Ship (SDTS) on the NAWCWD Sea Range. The SDTS got underway for sea trials in August 1999 after receiving a full range of repairs. The test ship had been damaged during live fire testing in May 1999.

Air Warfare area T&E requires integrating the sensor and engagement sub-systems of the applicable ship class combat systems while engaging ASCMs or acceptable surrogates as targets. Since these are short-range air defense systems, safe and effective testing requires use of a Self Defense Test Ship capable of being remotely operated during operationally realistic ship air defense scenarios. Results of these tests will be used to validate M&S to predict the Probability of Raid Annihilation (PRA) for various combat systems. PRA is a ship air (self) defense requirement, where a raid constitutes an attack by anti-ship cruise missiles. This OT&E of SSDS Mark 2 should be conducted concurrently with the phases of Self Defense Test Ship testing that will be required of the combat systems for the applicable ship classes: LPD 17, CVN 76, CVN 77, CVN(X), DD 21, and follow-on classes that have a PRA requirement. SSDS Mark 2 OT&E must include concurrent testing with the Rolling Airframe Missile Helicopter-Aircraft-Surface mode. The DDG-31 Decatur was Disposed of in support of Fleet training exercise07/21/2004.