The Sound Surveillance System (SOSUS) was a submarine detection system based on passive sonar developed by the United States Navy to track Soviet submarines. The system's true nature was classified with the name and acronym SOSUS themselves classified. The unclassified name Project Caesar was used to cover the installation of the system and a cover story developed regarding the shore stations, identified only as a Naval Facility (NAVFAC), being for oceanographic research. In 1985, as the fixed bottom arrays were supplemented by the mobile Surveillance Towed Array Sensor System (SURTASS) and other new systems were coming on line, the name itself changed to Integrated Undersea Surveillance System (IUSS). The commands and personnel were covered by the "oceanographic" term until 1991 when the mission was declassified. As a result, the commands, Oceanographic System Atlantic and Oceanographic System Pacific became Undersea Surveillance Atlantic and Undersea Surveillance Pacific, and personnel were able to wear insignia reflecting the mission.
A small waterplane area twin hull, better known by the acronym SWATH, is a catamaran design that minimizes hull cross section area at the sea's surface. Minimizing the ship's volume near the surface area of the sea, where wave energy is located, minimizes a vessel's response to sea state, even in high seas and at high speeds. The bulk of the displacement necessary to keep the ship afloat is located beneath the waves, where it is less affected by wave action. Wave excitation drops exponentially as depth increases, so wave action normally does not affect a submerged submarine at all. Placing the majority of a ship's displacement under the waves is similar in concept to creating a ship that rides atop twin submarines.
USNS Mizar (MA-48/T-AGOR-11/T-AK-272) was a vessel of the United States Navy. She was named after the star Mizar.
HMNZS Resolution (A14) was a hydrographic ship of the Royal New Zealand Navy (RNZN). Originally the United States Naval Ship USNS Tenacious (T-AGOS-17), the Stalwart-class ocean surveillance ship was used by the United States to locate and track Soviet submarines from 1989 to 1997, when she was transferred to the RNZN for use as a hydrographic survey ship. She served until 27 April 2012. She was subsequently sold to EGS Group, a private surveying company, and renamed RV Geo Resolution.
USNS Stalwart (T-AGOS-1) was a Modified Tactical Auxiliary General Ocean Surveillance Ship and the lead ship of her class.
USNS Invincible (T-AGM-24), also known as ex-AGOS 10, is one of two tracking ships operated by the Military Sealift Command. One of the radars it carries is the Cobra Gemini dual band, X band and S band, radar.
Stalwart-class auxiliary general ocean surveillance ships (T-AGOS) were a class of United States Naval Ship (USNS) auxiliary support Ocean Surveillance Ships commissioned between April 1984 and January 1990. Their original purpose was to collect underwater acoustical information using the Surveillance Towed Array Sensor System (SURTASS), a towed array passive sonar.
The AN/UQQ-2 Surveillance Towed Array Sensor System (SURTASS), colloquially referred to as the ship's "Tail", is a towed array sonar system of the United States Navy.
USNS Vindicator (T-AGOS-3) was a United States Navy Stalwart-class modified tactical auxiliary general ocean surveillance ship that was in service from 1984 to 1993. Vindicator then served in the United States Coast Guard from 1994 to 2001 as the medium endurance cutter USCGC Vindicator (WMEC-3). From 2004 to 2020, she was in commission in the National Oceanic and Atmospheric Administration (NOAA) fleet as the oceanographic research ship NOAAS Hi'ialakai.
USNS Triumph (T-AGOS-4) is a Stalwart-class ocean surveillance ship formerly of the United States Navy. She was struck from the Naval Vessel Register in 1995. On 1 October 2012 the ship was disposed of by Navy title transfer to the Maritime Administration. As of May 2015, Triumph was held as a reserve asset for spare parts for sister ships General Rudder and State of Michigan.
NRP Almirante Gago Coutinho (A523) is a ship of the Portuguese Navy' Dom Carlos I-class survey vessels. Before transfer to the Portuguese Navy, Almirante Gago Coutinho was formerly USNS Assurance (T-AGOS-5) of the United States Navy.
USNS Indomitable (T-AGOS-7) was a United States Navy Stalwart-class ocean surveillance ship in service from 1985 to 2002. From 2003 until 18 June 2014, she was in commission in the National Oceanic and Atmospheric Administration (NOAA) as the oceanographic research ship NOAAS McArthur II. As of 2018 it serves as a mother ship now named the Deep Submersible Support Vessel (DSSV) Pressure Drop for the crewed deep-ocean research submersible DSV Limiting Factor.
Prevail (IX-537) is a modified Stalwart-class auxiliary general ocean surveillance ship (AGOS) of the United States Navy previously operated by the U.S. Military Sealift Command as T-AGOS 8. Prevail was reclassified as Unclassified Miscellaneous (IX) in October 2003 and is unofficially referred to as TSV-1. In this context, TSV stands for Training Support Vessel, and should not be confused with the U.S. Army's USAV Spearhead Theater Support Vessel initiative.
USNS Adventurous (T-AGOS-13) was a Stalwart-class modified tactical auxiliary general ocean surveillance ship of the United States Navy in service from 1988 to 1992. She was in non-commissioned service in the Military Sealift Command from 1988 to 1992, operating during the final years of the Cold War. She was transferred to the National Oceanic and Atmospheric Administration (NOAA) in 1992 and in 2003 was commissioned into service with NOAA as the fisheries research ship NOAAS Oscar Elton Sette.
USNS Titan (T-AGOS-15) was a Stalwart-class modified tactical auxiliary general ocean surveillance ship in service in the United States Navy from 1989 to 1993. From 1996 to 2014, she was in commission in the National Oceanic and Atmospheric Administration (NOAA) fleet as the oceanographic research ship NOAAS Ka'imimoana.
USNS Relentless (T-AGOS-18) was a Stalwart-class modified tactical auxiliary general ocean surveillance ship in service in the United States Navy from 1990 to 1993. Since 1998, she has been in commission in the National Oceanic and Atmospheric Administration (NOAA) fleet as the fisheries research ship NOAAS Gordon Gunter.
USNS Able (T-AGOS-20) is a Victorious-class oceanographic survey ship in the service of the United States Navy's Military Sealift Command.
USNS Victorious (T-AGOS-19) is a Victorious-class ocean surveillance ship which was acquired by the U.S. Navy in 1991 and assigned to the Military Sealift Command (MSC) Special Missions Program.
USNS Impeccable (T-AGOS-23) is an Impeccable-class ocean surveillance ship acquired by the U.S. Navy in 2001 and assigned to Military Sealift Command's Special Missions Program.
The Impeccable-class ocean surveillance ship is a single-ship class of United States Navy special mission-support ship. The original intention was to build six undersea ocean-surveillance ships carrying a SURTASS passive towed array and a Low Frequency Active transducer array. Only the lead ship, USNS Impeccable (T-AGOS-23), was built.
United States
