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Saturday 19 August 2017

Wonsan and Nampo minelayer classes of the Republic of Korea Navy

Written by D-Mitch

RoKS Nampo, one of the most advanced minelayers in the world today
Today, some of the most advanced and most capable modern minelayer classes belong to the Republic of Korea Navy (South Korean Navy). This is the Wonsan class and its evolution, the Nampo class, which will be analyzed thoroughly in this article. The first ship in the Nampo class, RoKS Nampo with the pennant number 570, was launched just recently by the Hyundai Heavy Industries (HHI), on 27th of May of 2017. It is not known yet how many ships in the class will follow exactly but at least three more ships are expected. The designation name of the class is Mine Layer Ship (MLS)-II following the previous sole ship and predecessor of the type, MLS-I type, the Wonsan (560), which was delivered to the Republic of Korea Navy in 1998. Initially, South Korea was planning to build three MLS-I ships but due to budget constraints of that time only one vessel was completed. Big, modern, heavily armed, multi-purpose ships, these are definitely the most well equipped minelayers in the world today proving that the minelayer designs have still future.

The two Korean minelayer classes

MLS-I Wonsan (560)
MLS-II Nampo (570). Source here.
The general characteristics of the Wonsan class are 104m length, about 3,300 tons displacement at full load and a maximum speed of 22 knots and a range of 4,500n.m. with the speed of 15 knots. Its crew is 160. Its successor, the Nampo class, is about 10 meters longer, 1,000tons heavier and can achieve a bit higher speed. Due to increased automation the complement reaches 120 men. The Wonsan is developed based on the hull of Ulsan class Flight-I light frigate design sharing common electronic equipment while the Nampo class on the Incheon class (Hyundai HDF-3000/FFX-I) frigate which share also common electronic equipment though Nampos are about 1,000t heavier and have a more advanced submarine and mine-detecting equipment and countermeasure suite.

Ulsan class Flight-I light frigate
Incheon class (Hyundai HDF-3000/FFX-I) frigate
76mm and forward NOBONG
76mm and forward NOBONG
The Wonsan is equipped with the standard OTO Melara Compatto 3in (76.2mm) fully automatic gun installed forward of the bridge and on the bow deck. The gun has excellent performance in any kind of role, such as air-defence, anti-surface, anti-missile and shore bombardment role. It can hit air and surface targets at a distance of 12 km and 16 km respectively with a rate of fire 85 rounds and weight of shell greater than 6 kg. There are 85 ready rounds on the mount. The anti-aircraft armament completes two NOBONG twin 40mm gun turrets which are Korean derivative OTO Melara Breda twin 40mm gun systems (turrets are produced by Hanwha Defense Systems while cannons by S&T Dynamics). The system is loaded with 768 rounds and achieves a maximum rate of fire of about 300rds/min (per cannon) while it can engage targets effectively at 4km.

The aft NOBONG and the torpedo launchers of Wonsan
The armament completes two triple Korean Mk32 Mod 5 torpedo launchers, a Korean-built Mk32 launcher by Hanwha Defense Systems, for LIG Nex1 K745 Blue Shark anti-submarine torpedoes. Capable of penetrating 1.5 meter-thick steel, Blue Shark tracks the sound of enemy submarines and strikes enemy submarines. Blue Shark has a maximum speed of 45km with a 19km operational range.

FCS, NOBONG and Korean Mk32 Mod 5 torpedo launcher
S&T Dynamics KDagaie Mk2 not fully loaded
The ship is protected by two S&T Dynamics K (Korean) Dagaie Mk2 fully automatic decoy launching systems. Dagaie, originally developed by CSEE, is a short-range decoy system that accepts threat information from a number of sources, including combat management systems incorporating electronic support measures (ESM) modules or suites. The trainable launcher is loaded with cartridges, or suitcases, containing either 33 predirected Electro-Magnetic (EM) chaff rounds or 34 predirected infrared (IR) flares for confusion, distraction, and seduction. The 40 kilogram rockets have a 24 kilogram payload and a flight speed of 250 meters/second on average. Alternative suitcases are available to deploy decoy clouds at different altitudes and ranges. The Dagaie launcher is easily reloadable and fired by mortar automatically on receipt of a threat warning. Firing data are obtained by evaluating the threat relative to the platform situation, taking into account the threat’s bearing, relative wind direction and velocity, as well as the ship’s heading and speed. A solution is automatically proposed to give optimum decoy potential. This includes providing recommended helm orders. Reaction time is on average about five seconds from the observation of the threat to the launch of a countermeasure. The Mk 2 offers easier integration of equipment with a central processing system (NTDS) and centralized operation in conjunction with other EW equipment. Ammunition has been upgraded with the introduction of new LIR and LEM ammo, which require new software for firing. Also, the availability of the new electro-magnetic medium-range ammunition, REM, allows the Dagaie more capability to operate even without a jammer in an EW attack.

Modified photo of Wonsan class minelayer. For a high resolution image click here.
One of the two LCVP of Wonsan
Close-up photo of the LCVP
The flight deck of Wonsan is large enough to accommodate an MH-53 helicopter (variant of CH-53 designed for long range minesweeping missions), the largest and heaviest helicopter in the United States Armed forces which however is not included yet in the South Korean inventory. There is no hangar on board. The ship carries also two LCVP amidships that are used in mine-laying operations, training and other activities.

A bow view of Wonsan minelayer
The huge flight deck of Wonsan

Details of Wonsan's equipment

A US MH-53 aboard Wonsan

The stern doors for laying mines
One of the stern doors opened
The advanced minelaying system of the ship is produced by KHNT (Keumha Naval Technology Co Ltd.) and it is depicted below. Notice that the system covers the whole area under the large flight-deck and comprises three whole decks loaded with various mines including mooring mines, CAPTOR mines, magnetic and sound mines! CAPTOR mine, from the initials of enCAPsulated TORpedo, is an aluminum canister anchored to the ocean floor, fitted with homing torpedo with sensor suite design to attack ship based on sonar signatures it carries (see video). Of similar design is the system that equips the Nampo class.

K701 CAPTOR mine
K701 CAPTOR mine

The components of a CAPTOR mine

Wan Xiang captor mine. Source here.

The components and operational details of the giant Korean mine-laying system of Wonsan
From left to right: EO sensor, SPS-95
radar and Marconi S-1810 radar
The black-painted radar is the DA-05
while at the right corner is the ST-1802
The ship is equipped with a Marconi S-1810 2D air and surface search and target indication I (X)-band radar with a +70km range and 55km for target detection on small aircraft, a Thales DA-05 2D medium-range combined air and surface search and target-indication radar and a KDT SPS-95K search and tracking radar. In addition to those radars, the ship carries one Marconi RS ST-1802 fire control radar system (FCS), an electro-optronic sensor (probably a derivative of LIOD?), an AN/SQS-56 sonar and satellite communications (SATCOM) antennas.

The lead-ship of the new Korean minelayer class, Nampo, during sea trials
RoKS Nampo, world's most advanced minelayer today
As it was mentioned earlier, the Nampo class is the evolution of the Wonsan. This class is not only the most modern minelayer class in the world today but it is also one of the only 2-3 classes built worldwide the last decades that have designed for this exact role, the minelaying! The large majority of navies use either landing ships (such examples are the Polish Lublin class, the Greek Jason class, the Turkish Osman Gazi class etc.) or other kind of secondary surface combatants such as patrol boats or auxiliary vessels which their secondary role is to lay mines in war time. Moreover, unlike most mine countermeasure vessels, which are less than 1,000tons except a very few exceptions which are described briefly in the next paragraph, the MLS-II ships are about four times bigger (!) and have a powerful equipment equivalent in some cases to larger warships such as corvettes and light frigates.

The Hämeenmaa minelayer, flagship of the Finnish Navy today

Umkhonto SAM is launched from a
Finnish Navy Hämeenmaa-class
Stern view of an Uraga class minelayer
In this category of well-armed and modern minelayers, belong very few classes in the world. One such class is the 1,500 ton Hämeenmaa class of the Finnish Navy (Hämeenmaa and Uusimaa) which can lay about 150 mines and are equipped among others with an 8-cell Denel Umkhonto-IR VLS SAM system. The ships of the class though have no flight deck facilities. Another design, comparable to the Nampo class, is the giant 5,700-ton Uraga class of the Japanese Navy (vessels Uraga and Bungo) which can lay about 230 mines depending on the type. The Japanese ships though, till today, carry only one 76mm gun (only the second ship in the class) despite their great potentials for much heavier armament such as two Phalanx CIWS.

The giant Japanese minelayer, Bungo
All those classes together with the Nampo class, except the minelaying role have significant multi-role capabilities (ASW, logistic support, disaster relief operations, etc.) and act as the flagships of their navy’s mine warfare flotillas. From the basic description of the classes in the previous paragraph, it is easy to realize that the new Nampo class has the most powerful minelayers in the world today, at least until the Japanese vessels receive a proper armament.

The lead-ship of the new Korean minelayer class, Nampo, during sea trials

Hyundai WIA 3in (76.2mm) gun
Hyundai WIA 3in (76.2mm) gun
The Nampo is equipped with the standard Hyundai WIA 3in (76.2mm) fully automatic gun installed forward of the bridge. This gun system is a Korean-built OTO Melara 76mm gun of which some of its components are the same as on the OTO Melara naval guns (such as the barrel), most other subsystems are self designed and built such as the reloading system and control station, the hydraulics etc. The carbon composite cupola of the gun has been also improved achieving a radar cross section (RCS) about 80% smaller compared to its OTO Melara counterpart. Moreover, the gun system gun has an improved rate of fire compared to its Italian counterpart, achieving a rate of fire of 100 rounds per minutes (thanks I guess to a retrofit kit). The gun has excellent performance in any kind of role, such as air-defence, anti-surface, anti-missile and shore bombardment role. It can hit air and surface targets at a distance of 12 km and 16 km respectively. There are 80 ready rounds on the mount.

Modified photo of Nampo class minelayer. For a high resolution image click here.

LIG Nex1 K745 Blue Shark LWT torpedo
KMk32 launcher of a KDX-II DDG
Similar to Wonsan, the armament completes two triple Korean Mk32 Mod 5 torpedo launchers, a Korean-built Mk32 launcher by Hanwha Defense Systems, for LIG Nex1 K745 Blue Shark anti-submarine torpedoes. Capable of penetrating 1.5 meter-thick steel, Blue Shark tracks the sound of enemy submarines and strikes enemy submarines. Blue Shark has a maximum speed of 45 knots and carries a directed energy warhead at 19km. There are also two S&T Dynamics K6 12.7mm heavy machine guns (Korean built M2HB) that achieve a rate of fire approximately 600rds/min.

Rheinmetall MASS decoy launcher
Rheinmetall MASS decoy launcher
Image by Rheinmetall Defence
Each ship is protected by two Rheinmetall multi-ammunition softkill systems (MASS) which are installed amidships. The launcher is connected to the ship's sensors and protects ships from attacks by advanced, sensor-guided missiles, by launching decoys, that operate in all relevant wavelengths on the electromagnetic spectrum (ultra violet, electro-optical, laser, infrared and radar). Watch a video of the system in action here and here.

The large flight deck and hangar of Nampo; notice the VLS system at the back

In contrast to Wonsan, the Nampos do not have only the large flight deck for a heavy-sized helicopter equivalent to MH-53E Sea Dragon, but they do have also a large hangar to accommodate medium-sized helicopter. At the back of the helicopter hangar, the Nampos are fitted a with a 4-cell Hanwha Defense Systems K-VLS, a multi-purpose vertical launching system capable of loading and launching various ship-launching guided missiles. The system can deploy the LIG Nex1 Korean Ship based Surface to Air Anti-Missile Systems (K-SAAM) missiles to provide anti-air warfare defense capability to itself and friendly ships from hostile anti-ship missiles and aircraft, as well as the LIG Nex1 Red Shark K-ASROC, an anti-submarine missile.

Hanwha Defense Systems K-VLS

Red Shark K-ASROC components
The LIG Nex1 Red Shark torpedo, also called the K-ASROC for Korean Anti-Submarine ROCket, is a vertically launched long-range submarine torpedo that can strike enemy submarines that are outside the range of lightweight torpedoes. The Red Shark missile has a range of 12 miles (19 km) and carries a K745 Blue Shark torpedo which was mentioned earlier, that is deployed by parachute near the intended target. After release, the Blue Shark independently searches for the target. Red Shark, a ship-mounted long-range Korean anti-submarine missile, was successively developed and tested by South Korea's University of Science and Technology and the Korea Agency for Defense Development (ADD), to overcome the short range of conventional lightweight torpedoes and to attack enemy submarines from a distance. When attacking a target, a rocket containing Blue Shark, a lightweight torpedo, is fired vertically from the surface ship and Blue Shark is separated from the rocket above the water where the target is located and then it enters the water to seek out the target.  

Red Shark operation concept. By

Except the Red Shark that can be loaded on K-VLS (1 per cell), the  launcher can be loaded with 4 LIG Nex1 K-SAAM in each cell and thus to provide all weather medium-range anti-air multi-target defense with 16 SAAM. K-SAAM, also called Sea Bow, is intended to protect the RoKN's surface fleet from anti-ship cruise missiles and aircraft, thus acting as a Close-in Weapons System (CIWS) will replace the short-range Raytheon Rolling Airframe Missile (RAM) in providing close-in ship defence. The external appearance of K-SAAM looks almost identical to MBDA MICA and resembles also the Raytheon ESSM Block II in its operational characteristics. The missile, similarly to ESSM, has the ability to be "quad-packed and also employs inertial mid-course guidance and a dual microwave and imaging infrared seeker for terminal guidance. The system is capable of engaging multiple targets simultaneously while ti has also anti-surface mode. Based on its external appearance and dimensions, we should expect a maximum range of about 20km and a speed of Mach 3, similarly to MICA.

Details of K-SAAM. Via Ambassador at
LIG Nex1 K721 captor mine
LIG Nex1 K701 captor mine
As it was mentioned earlier for Wonsan class minelayer, the Nampo class is equipped with a very expensive and highly-sophisticated minelaying system giving the capability to the ship of laying precisely, at the target coordinates and depth, more than 500 mines (depending of the type) in a very short period of time. Below it is dipictured the system's components.

The advanced KHNT minelaying system's components
The decoys of TACM
TACM launching decoys
The Nampo class is also equipped with two LIG Nex1 SLQ-261K Torpedo Acoustic Counter Measure (TACM) systems designed to cope with active and/or passive torpedoes, wire or non wire-guided, launched alone or in salvo mode. TACM early detects and alerts against torpedo and redirects torpedo by way of high-powered acoustic jamming. The system is highly effective against both straight-running torpedo and homing guidance torpedo.

TACM operation concept. By

The SONATA EW suite. First row:
DFU, jammer (not included), CCU
LIG Nex1 SPS-550K multi-beam radar
The main radar of the ships is a LIG Nex1 SPS-550K medium to long-range air and surface surveillance multibeam 3D radar (maximum detection range up to 250km, 120km for aircraft and 50km for missiles; total 500 targets) that employs Digital Multi-Beam forming,
Pulse Doppler and Medium PRF Techniques to extract low RCS targets and to suppress the multipath effects from complex clutter. the vessels of the class are also equipped with one KDT SPG-540K fire control radar, a LIG Nex1 SAQ-540K Electro-Optical Targeting System (EOTS), a KDT SPS-300K 2D X-band navigation radar, an AN/UPX-27K identification device (IFF),a SQS-240 hull mounted-sonar, Towed Array Sonar System (TASS) capable of mine warfare and the LIG Nex1 SLQ-200(V)K SONATA ship-borne electronic warfare system without the jammers.

I believe, that after the commissioning of more units of the MLS-II type, we should expect Wonsan to be downgraded to training role if not at least be upgraded with new radars and equipment. 


  1. Great article on a ship class I was completely unaware of. Thanks!