The History of the Navy’s Self Defense Test Ship (SDTS) Program

Modern naval warfare requires constant testing and improvement of shipboard weapons and defensive systems. To accomplish this safely and effectively, the U.S. Navy developed a unique program known as the Self Defense Test Ship (SDTS).

The SDTS program allows the Navy to test new technologies, radar systems, and weapons in realistic at-sea conditions without putting sailors or operational ships at risk.

Why the Program Was Created

During the Cold War and the decades that followed, naval threats continued to evolve rapidly. Anti-ship missiles, advanced aircraft, and electronic warfare systems became increasingly sophisticated.

Testing these threats against operational Navy ships presented several challenges:

It placed sailors at risk during live-fire testing
It removed operational ships from fleet duties
It limited how realistically some weapons systems could be tested

To solve this problem, the Navy began developing the concept of a dedicated test platform—a ship used exclusively for evaluating naval combat systems and defensive technologies.

Early Test Ships

Before the USS Paul F. Foster assumed the role of the Navy’s Self Defense Test Ship, several vessels supported weapons testing and technology development.

One of the earliest and most notable test ships was USS Norton Sound (AVM-1). Originally commissioned as a seaplane tender during World War II, Norton Sound later became one of the Navy’s most important missile test platforms. Over several decades she supported the development and testing of numerous guided missile systems and played an important role in the early testing of technologies that eventually contributed to the Aegis Combat System.

Another important test platform was USS Gyatt (DDG-1). Originally a Gearing-class destroyer, Gyatt became one of the Navy’s first guided missile destroyers and served as an experimental platform for early naval missile systems. Her work helped pave the way for future guided missile destroyers and modern naval air defense systems.

The Navy also used ships such as USS Ozbourn (DD-846), a Gearing-class destroyer that supported weapons and combat systems testing. These ships provided valuable experience in evaluating new technologies and understanding how they would function aboard operational warships.

USS Decatur and the Modern SDTS Concept

The direct predecessor to the USS Paul F. Foster in the Self Defense Test Ship role was USS Decatur (DDG-31), a Charles F. Adams–class guided missile destroyer. Decatur served as an early dedicated Self Defense Test Ship, supporting the testing and evaluation of naval combat systems and shipboard defensive technologies.

Her work helped establish the concept of a dedicated at-sea test platform used to evaluate weapons systems under realistic operating conditions before they were deployed to the fleet.

The USS Paul F. Foster Joins the Program

When the USS Paul F. Foster (DD-964) was decommissioned in 2003 after many years of service as a Spruance-class destroyer, the Navy selected her to continue this important mission.

The ship was redesignated EDD-964 and converted into the Navy’s modern Self Defense Test Ship (SDTS).

Engineers installed systems that allow the ship to be operated remotely from shore, enabling live-fire weapons testing without a crew onboard during certain events. This capability allows the Navy to safely test defensive systems against realistic threats.

A Unique Capability

The Self Defense Test Ship provides a realistic environment for evaluating naval combat systems. During testing, engineers can evaluate the full defensive sequence used by modern warships:

Detection of incoming threats
Tracking and targeting by radar and combat systems
Engagement using shipboard defensive weapons

Because the ship can operate remotely, engineers can conduct high-risk test scenarios that would not be possible aboard operational ships with sailors onboard.

Supporting the Fleet’s Future

The SDTS program plays a critical role in the development of new naval technologies. It allows engineers to test systems thoroughly before they are deployed to operational ships, improving both safety and effectiveness.

The program also allows fleet ships and their crews to remain available for operational missions rather than being diverted for test events.

The Legacy of the USS Paul F. Foster

Through her role as the Navy’s Self Defense Test Ship, the USS Paul F. Foster continues to serve the fleet decades after her commissioning.

She carries forward the legacy of earlier test ships such as Norton Sound, Gyatt, Ozbourn, and Decatur, helping to test and refine the systems that protect today’s sailors and warships.

For the shipmates who served aboard her, it is a point of pride that the Paul F. Foster continues contributing to the defense of the United States Navy long after her time in the fleet.

Timeline of U.S. Navy Test Ships Leading to the SDTS

1940s–1980s
USS Norton Sound (AVM-1) serves as the Navy’s primary missile and technology test ship.

1950s–1960s
USS Gyatt (DDG-1) becomes one of the Navy’s earliest guided missile destroyer test platforms.

1960s–1970s
USS Ozbourn (DD-846) supports combat systems and weapons testing programs.

1980s–2003
USS Decatur (DDG-31) operates as the Navy’s Self Defense Test Ship, supporting evaluation of shipboard defensive systems.

2003–Present
USS Paul F. Foster (EDD-964) becomes the Navy’s modern Self Defense Test Ship, capable of both manned and remote-controlled live-fire testing.

⚓