M115 Maeklong ii Frigate

A fictional Thai frigate class named after "แม่น้ำ" (River in Thai).

Background:

• The Royal Thai Maritime Defence Forces (กองกำลังป้องกันทางทะเลแห่งราชอาณาจักรไทย) have initiated a next-generation GP frigate programme aimed at replacing the ageing Chao Phraya-class frigates during the 2030s. The programme was expected to modernise the surface combatant fleet.

• Following a competitive tender process involving multiple international shipbuilders, including DSME, CSSC, Uraga Dock Company, and Babcock, the selection was narrowed to Uraga Dock and Babcock in the final evaluation phase. This shortlisting indicated RTMDF’s preference for designs that balanced capability growth with industrial cooperation and long-term affordability, rather than pursuing high-end, capital-intensive platforms.

• The eventual selection of Uraga Dock Company highlighted a strategic shift towards deeper integration with domestic shipbuilding and support industries. Despite initial concerns raised by the Budget Bureau regarding design maturity and potential cost overruns, RTMDF assessed that Uraga Dock’s proposal offered greater flexibility in tailoring the platform to national operational requirements. Logistics, sustainment, and long-term industrial benefits were identified as decisive factors.

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Design:

• The M115 Maeklong-class frigate is a co-development effort between Uraga Dock and Thailand’s Marsun Shipyard. While its external form bears resemblance to the Japan Maritime Self-Defence Force’s Mogami-class frigates, the underlying design philosophy differs significantly. Rather than focusing on high-end naval warfare, the Maeklong-class emphasises general-purpose versatility, maritime security operations, and wartime patrol duties within medium-threat environments.

• The vessel has a displacement of approximately 4,100 tonnes, with an overall length of 115 metres and a beam of 14.9 metres. It is designed as a compact frigate, taking into account the physical limitations of domestic shipyards, many of which are only able to handle vessels of around 4,000 gross tonnes or less. In addition, constraints related to state-owned coastal land have influenced the overall size and layout of the design.

• This compact size also reflects an operational requirement of the Royal Thai Maritime Defence Forces (RTMDF) for a frigate that can berth at a wide range of ports. At present, Laem Tien Naval Base remains the primary military harbour capable of supporting larger warships. The Maeklong II-class is therefore expected to improve operational flexibility, logistical support, and access to additional ports across the country.

• Operationally, the class is optimised for the protection of Thailand’s Exclusive Economic Zone (EEZ), which exceeds 300,000 square kilometres. This mission profile reflects RTMDF’s assessment that persistent presence, endurance, and availability are more critical than peak combat capability in most anticipated scenarios. As such, the design places considerable emphasis on cost-efficient operation and reduced crewing requirements.

• In response to manpower shortages following the abolition of conscription, the Maeklong-class incorporates a high degree of automation and integrated management systems. These measures allow effective operation with smaller crews, aligning platform design with RTMDF’s reduced personnel strength of fewer than 30,000 active members.

• The class adopts a “Fitted For But Not With” (FFBNW) design approach, providing flexibility for future capability upgrades as threat environments evolve or budgets permit. The hull is designed to support the later installation of two 1,380 kW MTU generators, as well as the integration of the MONG(KUT) integrated mast (Multi-Operational Navigation & Governing – Kept Under Tower), which remains under development.

read it all, you say? so proud of you

Deployment:

Ships in class:

• FF-401 / T.D.S Maeklong (เรือหลวงแม่กลอง)
• FF-402 / T.D.S Thachin (เรือหลวงท่าจีน)
• FF-403 / T.D.S Pasak (เรือหลวงป่าสัก)
• FF-404 / T.D.S Tapi (เรือหลวงตาปี)
  

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Specification:

Type: Coastal Defense Frigate
Builder: Uraga-Sumitomo Dock Company / Marsun
Cost: $650 Million per unit include ToT
Length: 115m
Beam: 14.9m
Draft: 4.25m
Displacement: 3,500 tons standard loaded / 4,130 tons maximum loaded
Speed: >30 knots
Range: up to 5,800 nmi
Complement: 68
Endurance: 28 days

Installed power:

2 × MTU 12V 4000 M53 Generator Set

Propulsion: (CODLOG)

1 × General Electric LM2500 Gas Turbines
2 × MTU 16v 1163 M94 Diesel Engine
2 × Electric Engine
2 × Shaft

Combat system & Sensors: (TACTICOS CMS)

1 × TRS-4D Multi-Functional Radar
1 × Atlas ASO DSQS-24 Hull Mounted Sonar
1 × Atlas ELEKTRONIK ACTAS Towed Array Sonar
1 × SCANTER 2000 X-band Navigation radar
2 × Cobra 1M X/Ka Band Maritime Terminal Phase Transmitter (do 2 ways data-link for ESSM)

Electronics Warfare & Decoys:

1 × Harris ES-3601 Radar-ESM
1 × R&F DDF-255 Communication Electronic Support System
2 x 12 Terma Decoy DL-12T Decoy Launchers
4 × 6 Terma Decoy Mk.137 Decoy Launchers

Intervention system & Cybersecurity: (Azurites XDR/CWA)

Tactical Data Link:

• National Link-T
• Tactical Link-16

Armament:

• 1 × 76/62mm OTO Melara Super Rapid
• 1 × RIM-116 Rolling Airframe Missile
• 2 x 4 Naval Strike Missile Anti-ship Missile
• 2 × 3 Mark 32 Torpedo Launcher
• 1 × 8 cell of Mk.41 Vertical Launching System
  for AAW:
• 32 × CAMM-ER / 16 × CAMM-MR Anti-Air Missile
  for ASW:
• 8 × VL-ASROC Anti-Submarine Missile FFBNW

Boat:

• 2 × USV-10 / 10m RHIB

Aircraft:

• 1 × S-70B-7 Seahawk ASW Helicopter
• 1 × Marcus-B VTOL UAV

Machine operate:

Propulsion

• Throttle below 80% — Diesel Propelled
• Throttle over 80% — Gas turbine Propelled (Sprint speed)
• Brake (Hold) — Reverse
• Yaw (Hold) — Turned

Other functions:

• ActivateGroup1 — Port Light
• ActivateGroup2 — Multi-function Ship-to-ship cargo transfer tower
• ActivateGroup3 — Sided Ramp
• Pitch — Signal lamp (Elevation)
• Roll — Signal lamp (Azimuth)
• FireGuns — Signal lamp

Camera:

• CAM1 Torpedo station (Portside)
• CAM2 Torpedo station (Starboard)
• CAM3 Helicopter deck (The Stern)
• CAM4 Signal lamp (Portside)
• CAM4 Signal lamp (Starboard)
  

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Inspired:

• MMCS / Freedom-class

• Mogami-class frigate

• Maeklong-class frigate

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Ref.

• RTN White paper