The following is the Congressional Research Service Dec. 22, 2021, In Focus report, Navy TAGOS(X) Ocean Surveillance Shipbuilding Program: Background and Issues for Congress.
From the report
The Navy wants to procure in FY2022 the first of a planned new class of seven TAGOS(X) ocean surveillance ships. The Navy’s proposed FY2022 budget requests $434.4 million for the procurement of the first TAGOS(X).
TAGOS Ships in the Navy
TAGOS ships support Navy antisubmarine warfare (ASW) operations. As stated in the Navy’s FY2021 budget submission, TAGOS ships “use the Surveillance Towed-Array Sensor System (SURTASS) to gather undersea acoustic data. They also carry electronic equipment to process and transmit that data via satellite to shore stations for evaluation.”
In the designation TAGOS (also written as T-AGOS), the T means they are operated by the Military Sealift Command (MSC); the A means they are auxiliary (i.e., support) ships; the G means they have a general or miscellaneous mission; and the OS means the mission is ocean surveillance. In the program designation TAGOS(X), the X means that the new TAGOS ship’s precise design has not yet been determined.
Current TAGOS Ships
The Navy’s five aging TAGOS ships include four Victorious (TAGOS-19) class ships (TAGOS 19 through 22) that entered service in 1991-1993, and one Impeccable (TAGOS-23) class ship that entered service in 2000. As of the end of FY2020, all five were homeported at Yokohama, Japan. The ships use a Small Waterplane Area Twin Hull (SWATH) design, in which the ship’s upper part sits on two struts that extend down to a pair of submerged, submarine-like hulls . The struts have a narrow cross section at the waterline (i.e., they have a small waterplane area). The SWATH design has certain limitations, but has features (including very good stability in high seas) that are useful for SURTASS operations.
Quantity, Schedule, and Design
The Navy wants to build seven TAGOS(X) ships as replacements for its five in-service TAGOS ships. The Navy’s FY2021 budget submission called for procuring the first four TAGOS(X)s at a rate of one per year in FY2022-FY2025. The Navy’s notional design for the TAGOS(X) employs a SWATH design that would be larger and faster than the in-service TAGOS ships.
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