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Updated March 13, 2024
Navy TAGOS-25 Ocean Surveillance Shipbuilding Program:
Background and Issues for Congress
Introduction
features (including very good stability in high seas) that are
The Navy in FY2022 procured the first of a planned class
useful for SURTASS operations.
of seven new TAGOS-25 class ocean surveillance ships at a
cost of $434.4 million. The Navy’s FY2024 budget
Figure 1. USNS Impeccable (TAGOS-23)
submission showed that the ship’s estimated procurement
cost had subsequently grown to $789.6 million—an
increase of $355.2 million, or 81.8%. The Navy’s proposed
FY2024 budget requested $355.2 million in additional cost-
to-complete procurement funding to pay for this cost
growth. Under the Navy’s FY2024 budget submission, the
Navy wanted to procure the second TAGOS-25 class ship
in FY2025.
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 procurement
funding for the TAGOS-25 program.
Meaning of TAGOS Designation
In the designation TAGOS (also written as T-AGOS), the T
Source: U.S. Navy photograph accompanying “Ocean Surveil ance
means the ships are operated by the Military Sealift
Ships,” Military Sealift Command, accessed May 25, 2021.
Command (MSC); the A means they are auxiliary (i.e.,
support) ships; the G means they have a general or
Figure 2. USNS Effective (TAGOS-21) in Dry Dock
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.
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 FY2023, 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. Under the
like hulls (Figure 2). The struts have a narrow cross section
Navy’s FY2025 budget submission, the Navy wants to
at the waterline (i.e., they have a small waterplane area).
procure the second through fifth ships in the class in
The SWATH design has certain limitations, but it has
FY2026-FY2029 at a rate of one ship per year. The Navy’s
notional design for the TAGOS-25 class (Figure 4)
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Navy TAGOS-25 Ocean Surveillance Shipbuilding Program: Background and Issues for Congress
employs a SWATH design that would be larger and faster
Procurement Cost
than the in-service TAGOS ships (see Table 1).
The Navy estimates in its FY2024 and FY2025 budget
submissions that the first ship in the class will cost $789.6
Figure 3. TAGOS Ship with SURTASS Arrays
million 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
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
Source: Detail from slide 13, entitled “TAGOS(X) Concept of
work. Exercising the options would bring the cumulative
Operations (CONOPS),” in Industry Day briefing for TAGOS(X)
value of the contract to about $3,195.4 million (i.e., about
program, June 26, 2019, accessed May 26, 2021, at GovTribe.com.
$3.2 billion). The Navy stated that it received two offers
Figure 4. Notional Navy Design for TAGOS-25
(i.e., Austal’s offer and one other offer).
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, 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
Source: Artist’s rendering accompanying press released entitled
growth and resulting estimated $789.6 million procurement
“Halter Marine Secures Contract for Industrial Studies for T-AGOS
cost of the first ship in the class.
Program,” Halter Marine, July 20, 2020.
Procurement Funding
Table 1. TAGOS Ship Designs
The Navy’s proposed FY2024 budget requested $355.2
TAGOS-
TAGOS-
TAGOS-25
million in the cost-to-complete funding for the first
19
23
(notional)
TAGOS-25 ship. The Navy’s proposed FY2025
shipbuilding budget requests no procurement funding for
Length
235 feet
282 feet
356 feet
the TAGOS-25 program. The Senate Appropriations
Committee, in its report on the FY2024 DOD
Maximum speed
10 knots
13 knots
20 knots
Appropriations Act (S. 2587), recommended transferring
Displacement
3,384 tons
5,370 tons
8,500 tons
the $355.2 million from the cost-to-complete line to the
TAGOS-25 procurement line in the Navy’s shipbuilding
Accommodations
~48
54
68
account. The report also recommended a rescission of
Sources: “Ocean Surveil ance Ships - T-AGOS,” U.S. Navy, and (for
$158.3 million in FY2022 TAGOS-25 procurement funding
TAGOS-25) slide 22, entitled “T-AGOS Class Comparison,” from
(see Section 8045 of S. 2587 and page 275 of the
Industry Day briefing for TAGOS(X) program, June 26, 2019,
committee’s report) and realigning the $158.3 million to the
accessed May 26, 2021, at GovTribe.com.
FY2024 TAGOS procurement funding line, making for a
total recommended funding level of $513.5 million in the
The Navy’s desire to replace the five in-service TAGOS
FY2024 TAGOS-25 procurement funding line. The report
ships with seven larger and faster TAGOS-25s can be
discusses the TAGOS-25 program on page 136. Section
viewed as a response by the Navy to the submarine
8094 of H.R. 4365 and Section 8096 of S. 2587 continue
modernization efforts of countries such as China and
U.S. content requirements for TAGOS-25 auxiliary
Russia. For more on China’s submarine modernization
equipment, including pumps and propulsion shafts.
effort, see CRS Report RL33153, China Naval
Modernization: Implications for U.S. Navy Capabilities—
Ronald O'Rourke, Specialist in Naval Affairs
Background and Issues for Congress, by Ronald O'Rourke.
IF11838
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Navy TAGOS-25 Ocean Surveillance Shipbuilding Program: Background and Issues for Congress
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