The Sound Surveillance System (SOSUS) was a passive sonar system 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 twin-hull ship 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, maximizes a vessel's stability, 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.
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.
A towed array sonar is a system of hydrophones towed behind a submarine or a surface ship on a cable. Trailing the hydrophones behind the vessel, on a cable that can be kilometres long, keeps the array's sensors away from the ship's own noise sources, greatly improving its signal-to-noise ratio, and hence the effectiveness of detecting and tracking faint contacts, such as quiet, low noise-emitting submarine threats, or seismic signals.
USNS Stalwart (T-AGOS-1) was a Modified Tactical Auxiliary General Ocean Surveillance Ship and the lead ship of her class.
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 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.
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 manned 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 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 Capable (T-AGOS-16) was a Stalwart-class modified tactical auxiliary general ocean surveillance ship of the United States Navy in service from 1989 to 2004. In 2008, she was commissioned into service in the National Oceanic and Atmospheric Administration as the oceanographic research ship NOAAS Okeanos Explorer.
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.
Geophysical MASINT is a branch of Measurement and Signature Intelligence (MASINT) that involves phenomena transmitted through the earth and manmade structures including emitted or reflected sounds, pressure waves, vibrations, and magnetic field or ionosphere disturbances.
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 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.
An underwater acoustic positioning system is a system for the tracking and navigation of underwater vehicles or divers by means of acoustic distance and/or direction measurements, and subsequent position triangulation. Underwater acoustic positioning systems are commonly used in a wide variety of underwater work, including oil and gas exploration, ocean sciences, salvage operations, marine archaeology, law enforcement and military activities.
The Hibiki-class ocean surveillance ship is a class of surveillance ships operated by the Japan Maritime Self-Defense Force. The ships have a small-waterplane-area twin hull (SWATH) design.
JS Harima (AOS-5202) is a Hibiki-class ocean surveillance ship of Japan Maritime Self-Defense Force.
JS Aki (AOS-5203) is a Hibiki-class ocean surveillance ship of Japan Maritime Self-Defense Force.
Japan