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Updated May 18, 2023
Navy TAGOS-25 (Previously TAGOS[X]) Ocean Surveillance
Shipbuilding Program: Background and Issues for Congress
Introduction
Figure 1. USNS Impeccable (TAGOS-23)
The Navy in FY2022 procured the first of a planned class
of seven new TAGOS-25 class ocean surveillance ships at a
cost of $434.4 million. The Navy’s FY2024 budget
submission shows that the ship’s estimated procurement
cost has since grown to $789.6 million—an increase of
$355.2 million, or 81.8%. The Navy’s proposed FY2024
budget requests $355.2 million in additional cost-to-
complete procurement funding to pay for this cost growth.
The Navy wants to procure the second TAGOS-25 class
ship in FY2025.
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
Source: U.S. Navy photograph accompanying “Ocean Surveil ance
ocean surveillance. The TAGOS-25 program was
Ships,” Military Sealift Command, accessed May 25, 2021.
previously known as the TAGOS(X) program, with the (X)
meaning that the precise design for the ship had not yet
Figure 2. USNS Effective (TAGOS-21) in Dry Dock
been determined. Some Navy budget documents may
continue to refer to the program that way.
TAGOS Ships in the Navy
TAGOS ships (Figure 1 and Figure 2) support Navy
antisubmarine warfare (ASW) operations. As stated in the
Navy’s FY2024 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.

Current TAGOS Ships
Source: U.S. Navy photograph 070913-N-2638R-004 posted at
The Navy’s five aging TAGOS ships include four
Wikimedia Commons, accessed May 25, 2021.
Victorious (TAGOS-19) class ships (TAGOS 19 through
22) that entered service in 1991-1993, and one Impeccable
TAGOS-25 Program
(TAGOS-23) class ship that entered service in 2000. As of
the end of FY2021, all five were homeported at Yokohama,
Quantity, Schedule, and Design
Japan. The ships use a Small Waterplane Area Twin Hull
The Navy wants to procure seven TAGOS-25 class ships as
(SWATH) design, in which the ship’s upper part sits on two
replacements for its five in-service TAGOS ships. The first
struts that extend down to a pair of submerged, submarine-
TAGOS-25 class ship was procured in FY2022. The Navy
like hulls (Figure 2). The struts have a narrow cross section
wants to procure the second through fifth ships in the class
at the waterline (i.e., they have a small waterplane area).
in FY2025-FY2028 at a rate of one ship per year. The
The SWATH design has certain limitations, but it has
Navy’s notional design for the TAGOS-25 class (Figure 4)
features (including very good stability in high seas) that are
employs a SWATH design that would be larger and faster
useful for SURTASS operations.
than the in-service TAGOS ships (see Table 1).

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Navy TAGOS-25 (Previously TAGOS[X]) Ocean Surveillance Shipbuilding Program: Background and Issues for Congress
Figure 3. TAGOS Ship with SURTASS Arrays
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 budget submission that
the first ship in the class will cost $789.6 million to procure
and that subsequent ships in the class will cost about $430
million each in then-year dollars to procure. As mentioned
earlier, the estimated procurement cost of the first ship has
grown by $355.2 million, or 81.8%. The Navy’s FY2024
budget submission states that this cost growth is “due to
Source: Detail from slide 13, entitled “TAGOS(X) Concept of
several factors affecting shipbuilding prices including direct
Operations (CONOPS),” in Industry Day briefing for TAGOS(X)
material inflation, supply chain challenges, and increased
program, June 26, 2019, accessed May 26, 2021, at GovTribe.com.
non-recurring engineering costs.”
Figure 4. Notional Navy Design for TAGOS-25
Acquisition Strategy and Contract Award
The Navy wants to use a single shipbuilder to build all
seven TAGOS-25s. The Navy posted the request for
proposals (RFP) for a detailed design and construction
(DD&C) contract for the program on November 19, 2021,
and amended it on December 21, 2021. Responses to the
RFP were due by April 19, 2022.
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
Source: Artist’s rendering accompanying press released entitled
construction of up to seven TAGOS 25s plus associated
“Halter Marine Secures Contract for Industrial Studies for T-AGOS
work. Exercising the options would bring the cumulative
Program,” Halter Marine, July 20, 2020.
value of the contract to about $3,195.4 million (i.e., about
$3.2 billion). The Navy stated that it received two offers
Table 1. TAGOS Ship Designs
(i.e., Austal’s offer one other offer).
TAGOS-
TAGOS-
TAGOS-25
Issues for Congress

19
23
(notional)
Potential issues for Congress for the TAGOS-25 program
Length
235 feet
282 feet
356 feet
include the reasons for the 81.8% cost growth on the first
ship in the class and the risk of further cost growth on the
Maximum speed
10 knots
13 knots
20 knots
first ship.
Displacement
3,384 tons
5,370 tons
8,500 tons
FY2024 Procurement Funding
Accommodations
~48
54
68
The Navy’s proposed FY2024 budget requests $355.2
Sources: “Ocean Surveil ance Ships - T-AGOS,” U.S. Navy, and (for
million in cost-to-complete procurement funding for the
TAGOS-25) slide 22, entitled “T-AGOS Class Comparison,” from
first ship in the class.
Industry Day briefing for TAGOS(X) program, June 26, 2019,
accessed May 26, 2021, at GovTribe.com.
Ronald O'Rourke, Specialist in Naval Affairs
The Navy’s desire to replace the five in
IF11838
-service TAGOS
ships with seven larger and faster TAGOS-25s can be


https://crsreports.congress.gov

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Navy TAGOS-25 (Previously TAGOS[X]) Ocean Surveillance Shipbuilding Program: Background and Issues for Congress


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https://crsreports.congress.gov | IF11838 · VERSION 20 · UPDATED

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