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Auxiliary Submarine Rescue Ship (ASR-II)

Daewoo Shipbuilding & Marine Engineering (DSME) was awarded on 07 December 2018 a contract for the construction of a new auxiliary submarine rescue ship (ASR-II) for the Republic of Korea Navy (RoKN). The 5,200-tonne vessel is expected to be delivered to the service by the end of 2022 as part of a deal signed with the country's Defense Acquisition Program Administration (DAPA) worth KRW444 billion (USD397 million). The ASR-II, which is expected to feature a helicopter deck and reach speeds of up to 20 kt, will have a 'center well' (moon pool) through which a deep-sea rescue vessel (DSRV) will be deployed to rescue the crews of distressed submarines at depths of up to 500 m amid waves as tall as 4 m. The 'center well' will also allow for broader submarine support operations in addition to underwater exploration, according to DAPA. The vessel will embark a remotely operated vehicle that will be capable of operating at depths of up to 1,000 m.

The RoKN currently operates a multipurpose submarine rescue ship - the 103 m long, 4,300-ton RoKS Cheonghaejin - which was commissioned in November 1996 and can operate in waves of 2 m or smaller. The ship relies on an A-frame to launch and recover the DSRVs. The service also operates a 107 m, 3,500-ton, helicopter-capable multipurpose salvage ship named RoKS Tongyeong , which is designed to meet the submarine rescue role. Both ships were built by DSME.

Underwater positioning and tracking technology from Sonardyne International Ltd. is to be used to support search and recovery operations undertaken by the Republic of Korea Navy’s (RoKN’s) new auxiliary submarine rescue ship (ASR-II). Through a December 2019 contract with GE’s Power Conversion business, the ASR-II will be fitted with Sonardyne’s Ranger 2 Ultra-Short BaseLine (USBL) system. This will interface onboard the vessel with GE’s class leading Seastream™ Dynamic Position (DP) control system providing accurate and fast position reference updates during critical station keeping activities.

The Ranger 2 onboard the ASR-II will also be used to simultaneously track the position of, and communicate with, Sonardyne instrumentation fitted to the new, untethered Deep Search Rescue Vehicle (DSRV) that is being built to operate from the ship when it comes into service. Ranger 2 is installed on a global fleet of DP vessels operating within defence, offshore energy, ocean research and commercial survey. Its success in meeting the diverse operational requirements of these sectors is built around Sonardyne’s versatile 6G hardware and Wideband 2 signal technology platforms. This combination enables underwater targets to be tracked beyond 11 km, position updates to be acquired every second, and for a vessel to work in any water depth, shallow or deep.

Sonardyne’s order from GE’s Power Conversion business includes everything the ASR-II will need to achieve the best performance from its Ranger 2 USBL during exercises or in the event of a submarine rescue operation. This includes a seabed-deployed 3,000 m-rated Dynamic Positioning Transponder 6 (DPT 6) with recovery floatation collar to provide high accuracy USBL positioning for reliable station keeping, even when operating near sources of potential noise interference such as other naval vessels. The control room software will be fitted with a Ranger 2 Marine Robotics Pack, which unlocks an additional range of features to enable the vessel crew to both track the DSRV and also communicate with it by sending and receiving status messages.

Finally, Sonardyne will also supply a deployment machine and gate valve, through which the Ranger 2 HPT 5000 USBL transceiver will be deployed through the hull of the ASR-II. The HPT 5000 enables underwater targets to be tracked over a wide range of water depths and elevations so is perfect for vessels needing to undertake different tasks on a regular basis.

The ASR-II and its moonpool-deployed DSRV are being built under South Korea’s Defense Acquisition Program Administration as a replacement for the submarine rescue ship RoKS Cheonghaejin. The 5,200-tonne ASR-II is expected to be delivered to the RoKN by the end of 2022.