Navy TAGOS-25 Ocean Surveillance Shipbuilding Program: Background and Issues for Congress

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Updated January 23, 2025

Navy TAGOS-25 Ocean Surveillance Shipbuilding Program: Background and Issues for Congress

Introduction

The Navy in FY2022 procured the first of a planned class of seven new TAGOS-25 class ocean surveillance ships. Under the Navy’s FY2025 budget submission, the Navy is proposing to defer procurement of the second TAGOS-25 class ship from FY2025 to FY2026. The Navy’s proposed FY2025 shipbuilding budget requests no FY2025 procurement funding for the TAGOS-25 program.

Meaning of TAGOS Designation

In the designation TAGOS (also written as T-AGOS), the T means the ships 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.

TAGOS Ships in the Navy

TAGOS ships (Figure 1 and Figure 2) support Navy antisubmarine warfare (ASW) operations. As stated in the Navy’s FY2025 budget submission, TAGOS ships “gather underwater acoustical data to support the mission of the Integrated Undersea Surveillance System (IUSS) by providing a ship platform capable of theater anti-submarine acoustic passive and active surveillance.… The two current classes of [TAGOS] surveillance ships use Surveillance Towed-Array Sensor System (SURTASS) equipment to gather undersea acoustic data.” Figure 3 shows a simplified diagram of a TAGOS-25 ship with its SURTASS arrays.

Figure 1. USNS Impeccable (TAGOS-23)

Source: U.S. Navy photograph accompanying “Ocean Surveillance Ships,” Military Sealift Command, accessed May 25, 2021.

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 FY2023, 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 (Figure 2). 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 it has features (including very good stability in high seas) that are useful for SURTASS operations.

Figure 2. USNS Effective (TAGOS-21) in Dry Dock

Source: U.S. Navy photograph 070913-N-2638R-004 posted at Wikimedia Commons, accessed May 25, 2021.

Figure 3. TAGOS Ship with SURTASS Arrays

Source: Detail from slide 13, entitled “TAGOS(X) Concept of Operations (CONOPS),” in Industry Day briefing for TAGOS(X) program, June 26, 2019, accessed May 26, 2021, at GovTribe.com.

Navy TAGOS-25 Ocean Surveillance Shipbuilding Program: Background and Issues for Congress

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TAGOS-25 Program

Class Name On January 10, 2025, the Navy announced that TAGOS-25 class ships would be called the Explorer class, “in honor of those who made discoveries under sea, on land, and in the skies above,” and that the first two ships in the class (TAGOS-25 and TAGOS-26) would be named Don Walsh and Victor Vescovo, respectively. Given the name selected for the first ship, the class might also come to be known as the Don Walsh class or Walsh class for short.

Quantity, Schedule, and Design The Navy wants to procure seven TAGOS-25 class ships as replacements for its five in-service TAGOS ships. The first TAGOS-25 class ship was procured in FY2022. Under the Navy’s FY2025 budget submission, the Navy wants to procure the second through fifth ships in the class in FY2026-FY2029 at a rate of one ship per year. The Navy’s notional design for the TAGOS-25 class (Figure 4) employs a SWATH design that would be larger and faster than the in-service TAGOS ships (see Table 1).

Figure 4. Notional Navy Design for TAGOS-25

Source: Artist’s rendering accompanying press released entitled “Halter Marine Secures Contract for Industrial Studies for T-AGOS Program,” Halter Marine, July 20, 2020.

Table 1. TAGOS Ship Designs

TAGOS-

19

TAGOS-

23

TAGOS-25

(notional)

Length 235 feet 282 feet 356 feet

Maximum speed 10 knots 13 knots 20 knots

Displacement 3,384 tons 5,370 tons 8,500 tons

Accommodations ~48 54 68

Sources: “Ocean Surveillance Ships - T-AGOS,” U.S. Navy, and (for TAGOS-25) slide 22, entitled “T-AGOS Class Comparison,” from Industry Day briefing for TAGOS(X) program, June 26, 2019, accessed May 26, 2021, at GovTribe.com.

The Navy’s desire to replace the five in-service TAGOS ships with seven larger and faster TAGOS-25s can be viewed as a response by the Navy to the submarine modernization efforts of countries such as China and Russia. For more on China’s submarine modernization effort, see CRS Report RL33153, China Naval Modernization: Implications for U.S. Navy Capabilities— Background and Issues for Congress, by Ronald O'Rourke.

Procurement Cost The Navy estimates in its FY2024 and FY2025 budget submissions that the first ship in the class will cost $789.6 million to procure—an increase of $355.2 million, or 81.8%, from its previously estimated cost. The Navy’s FY2024 budget submission stated that this cost growth is “due to several factors affecting shipbuilding prices including direct material inflation, supply chain challenges, and increased non-recurring engineering costs.”

Contract Award On May 18, 2023, the Navy announced that it had awarded Austal USA, a shipyard in Mobile, AL, a $113.9 million fixed-price incentive (firm target) and firm-fixed-price contract for detail design of the TAGOS-25 class. The contract includes options for the detail design and construction of up to seven TAGOS-25s plus associated work. Exercising the options would bring the cumulative value of the contract to about $3,195.4 million (i.e., about $3.2 billion). The Navy stated that it received two offers (i.e., Austal’s offer and one other offer). On May 30, 2024, the Navy awarded Austal USA a $516 million contract modification, exercising an option for long-lead time material and detail design and construction (DD&C) of the first ship in the class.

Issues for Congress

Potential issues for Congress include the reasons for the 81.8% cost growth on the first ship in the class, the risk of further cost growth on the first ship, a reported one-year delay in the design and construction of the first ship, why the Navy wants to defer the procurement of the second ship from FY2025 to FY2026, and why the Navy in its FY2025 budget submission appears to have increased the estimated procurement costs of the sixth and seventh ships in the class (which are to be procured after the FY2026-FY2029 Future Years Defense Plan [FYDP])—but not those of the second through fifth ships in the class (which are to be during the FYDP)—to figures that appear consistent with the cost growth and resulting estimated $789.6 million procurement cost of the first ship in the class.

Procurement Funding

The Navy’s proposed FY2025 shipbuilding budget requests no FY2025 procurement funding for the TAGOS-25 program, which is line 992 in the Navy’s FY2025 shipbuilding account. The joint explanatory statement for the House-Senate agreement on the FY2025 National Defense Authorization Act (NDAA) (H.R. 5009); the House Appropriations Committee, in its report (H.Rept. 118-557 of June 17, 2024) on the FY2025 DOD Appropriations Act (H.R. 8774); and the Senate Appropriations Committee, in its report (S.Rept. 118-204 of August 1, 2024) on the FY2025 DOD Appropriations Act (S. 4921), recommended no FY2025 procurement funding for the TAGOS-25 program. Section 8094 in both H.R. 8774 and S. 4921 would continue U.S. content requirements for all TAGOS-25 auxiliary equipment, including pumps and propulsion shafts.

Ronald O'Rourke, Specialist in Naval Affairs

IF11838

Navy TAGOS-25 Ocean Surveillance Shipbuilding Program: Background and Issues for Congress

https://crsreports.congress.gov | IF11838 · VERSION 31 · UPDATED

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