HJ Heavy Industries Geomdoksuri-B Batch-II

History

The HJ Heavy Industries Geomdoksuri-B Batch-II is a South Korean fast patrol craft developed for the Republic of Korea Navy. It is also designated Patrol Killer Medium Rocket and forms part of the broader Patrol Killer Experimental program.

The craft is intended for coastal surveillance, defense, and rapid response against surface threats. Its expected operating areas include the contested littoral waters near the Northern Limit Line in the Yellow Sea.

The Geomdoksuri-B program was created to replace aging Chamsuri-class patrol boats that had served for more than 20 years. The first production phase, Batch-I, ran from 2017 to 2022 and supplied the navy with rocket-armed patrol craft optimized for littoral operations.

South Korea's Defense Acquisition Program Administration launched the Batch-II program in 2022. The first Batch-II vessels were launched in 2025, establishing that year as the first confirmed physical milestone for the variant. The first craft subsequently completed sea trials.

On 14 August 2026, the first Batch-II craft was transferred to the Republic of Korea Navy at HJ Heavy Industries' Yeongdo shipyard in Busan. The delivery was reported by Janes and K Defense News.

Design

The Geomdoksuri-B Batch-II retains broadly the same equipment arrangement as Batch-I. Its principal changes concern combat-system integration, operator interfaces, resistance to electronic jamming, and the performance of major equipment.

The compact vessel uses waterjet propulsion and can reach approximately 40 knots. Its speed and armament are intended to support rapid reactions to small surface threats in congested coastal waters.

Combat systems

Batch-II integrates the control and launch functions of the 130 mm guided-rocket system and the 12.7 mm remote-controlled weapon system with the combat management system. This arrangement is intended to shorten the sequence between detecting a target and engaging it.

The equipment fit includes search radar, surveillance radar, an electro-optical tracking system, electronic-warfare equipment, and a maritime operational satellite communications system. Improved anti-jamming capability is intended to increase the vessel's resilience in an electronic-warfare environment.

Armament

The principal gun is a 76 mm Hyundai WIA naval weapon. A 12-cell launcher carries 130 mm Biryong guided rockets for engagements against small and fast-moving surface targets. Remotely operated 12.7 mm weapon stations provide additional close-range firepower.

Program status

Following its August 2026 delivery, the first Batch-II craft was scheduled to complete the Republic of Korea Navy's operational introduction process before deployment to frontline waters. DAPA planned to deliver three additional Batch-II vessels before the end of 2026.

Variants

• Geomdoksuri-B Batch-I: Initial production configuration delivered under a program conducted from 2017 to 2022.
• Geomdoksuri-B Batch-II: Follow-on configuration with improved combat-system integration, operator usability, equipment performance, and anti-jamming capability.

Operators

• Republic of Korea Navy: Received the first Batch-II craft on 14 August 2026. Three additional vessels were planned for delivery before the end of that year.

Specifications (Geomdoksuri-B Batch-II)

General characteristics

• Type: Fast patrol craft
• Displacement: Approximately 230 tonnes
• Length: 44 m
• Beam: 7 m
• Crew: 20–23 personnel
• Propulsion: Waterjets

Performance

• Maximum speed: Approximately 40 knots

Armament

• Naval gun: One 76 mm Hyundai WIA gun
• Guided rockets: One 12-cell launcher for 130 mm Biryong guided rockets
• Remote weapons: Remotely operated 12.7 mm weapon stations

Sensors and systems

• Radar: Search radar and surveillance radar
• Electro-optical equipment: Electro-optical tracking system
• Electronic warfare: Electronic-warfare equipment with improved anti-jamming capability
• Command and control: Integrated combat management system
• Communications: Maritime operational satellite communications system

Related equipment

The Geomdoksuri-B is the smaller patrol-craft branch of South Korea's wider PKX family. The broader program also produced the larger Geomdoksuri-A missile craft. An overview of the earlier PKX family is available from Naval Technology.

The Chamsuri class is the direct predecessor that the Geomdoksuri-B program was designed to replace.