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Najin class

Coastal frigate

Najin class

The Najin class frigates are the largest warships in the North Korean navy, but were badly outdated design even before they were laid down

Country of origin North Korea
Entered service 1973
Crew 180 men
Sea endurance ~ 30 days (?)
Dimensions and displacement
Length 100 m
Beam 10 m
Draught 4.7 m
Displacement, standard ?
Displacement, full load 1 500 tons
Propulsion and speed
Speed 25 knots
Range 7 400 km
Propulsion 2 x diesel engines, w/15 000 shp, 2 shafts
Helicopters none
Artillery 2 x 100-mm guns, 2 x AK-630 30-mm CIWS, 2 x twin 57-mm AA guns, 6 x twin 25-mm AA guns
Missiles 3M-24 Uran (SS-N-25 Switchblade) anti-ship missiles
Torpedoes none
Other 2 x RBU-1200 ASW rocket launchers, 2 x depth charge throwers, 2 x depth charge rails, up to 30 mines


   North Korea's indigenously-built Najin class frigates are the largest warships in its navy, and serve as the flagships of its eastern and western fleets, respectively.

   Though it has often been suggested that the Najin class frigates are clones of the Soviet Kola class frigates, their layout is very different (although the Kola class almost certainly influenced the design). Though regardless of their origins, the Najin class were nonetheless completed with similar armament and electronics to those used in the Kola class; this was a major mistake on North Korea's part, as the Kolas were badly obsolete at the time the FF-531 and FF-591 entered service, and were in the process of being retired and broken-up for scrap.

   Two vessels in the class were constructed; the FF-531 and FF-591, which were commissioned in 1973 and 1975, respectively. They were built in Najin, North Korea (exactly which shipyard built them has never been publicized), and are the largest warships ever constructed by that nation. Exactly how many Najin class frigates were constructed (and how many remain in service) remains disputed. The Naval Institute Guide to Combat Fleets of the World believes that 4 were completed (with 2 now retired), but most sources only recognize the existence of FF-531 and FF-591.

   The Najin class frigates have a raked bow, a flush deck, and a transom stern. The superstructure includes a large, bulky, rectangular conning tower (common of fleet warships built in the 1950s). There are two raked funnels with oblong cross-sections and flat caps, with a large lattice-like mast over the front of the forward funnel, and a smaller mast in front lf the aft funnel. Two cubic turrets are mounted on the deck (one fore and one aft), with superfiring anti-aircraft gun mounts inside open-top 360-degree shields. The overall appearance is evocative of European and Russian warships of the mid-1950s.

   As built, the electronics suite of the Najin class included a "Square Tie" air search radar, a "Pot Head" surface search radar, a "Pot Drum" navigation radar, a "Drum Tilt" fire control radar, and a "Stag Horn" sonar. Note that any of these systems may have been replaced with later models during subsequent refits. It is also possible, given North Korea's poor supply situation and international relations, that some of these systems may have even been deactivated or removed without replacement.

   The main battery of the Najin class consists of two single-gun turrets for the B-34 pattern 1940 100-mm/L56 gun, one mounted forward, the other aft. This weapon elevates through -8 to +85 degrees at up to 10 degrees/second, and traverses 352 degrees at up to 20 degrees/second. It fires a 15.6 kg projectile at a rate of fire of up to 10 rounds/minute to a maximum range of 22.2 km, and an anti-aircraft ceiling of 10 km. Because of its poor rates of fire and traversal, the B-34 was never adequate as a dual-purpose gun even in World War 2, and for the same reasons it would not be effective against small and fast watercraft today. As it also lacks the capabilities needed to compete with contemporary dual-purpose guns (its turret is fully-manned with little automation, and isn't even fully-enclosed), the only foreseeable role in which the B-34 would still be effective is for shore bombardment.

   The anti-aircraft battery of the Najin class is exceptionally heavy, but just as dated as its main battery. The primary anti-aircraft gun is the ZIF-31 57-mm automatic cannon, fitted to the Najin class fore and aft in shielded (but still open-topped) twin-gun mounts, superfiring over the fore and aft B-35 main guns. This weapon traverses to +/-200 degrees at 27 degrees/second, and elevates from -10 through +85 degrees at 22 degrees/second. It fires a 6.4 kg projectile out to a maximum range of 8.4 km, at up to 50 rounds/minute/barrel. While the ZIF-31 is accurate and exceptionally powerful, its slow traversal, small magazine capacity, and outdated fire control system do not lend well to being effective against modern warplanes (or even fast-moving surface targets), and it is doubtful that the ZIF-31 could defeat small and fast-moving anti-ship missiles, like the MM.38 Exocet or the RGM-84 Harpoon.

   The anti-aircraft battery also includes 6 2M-3 twin-gun turrets armed with 25-mm automatic cannons, for a total of 12 guns. These weapons traverse through 360 degrees at up to 40 degrees/second, and elevate from -10 through +85 degrees at up to 70 degrees/second. It fires a 0.281 kg projectile at up to 450 rounds/minute/barrel out to a maximum range of 3 000 m, with an anti-aircraft ceiling of 2 800 m. While this weapon is still fairly capable against modern aircraft, its fire control system is badly outdated, and its range is very short.

   The Najin class were also recently fitted with what appears to be two AK-630 30-mm CIWS turrets. These would finally provide it with both modern anti-aircraft capabilities and a weapon effective against missiles, but it still doesn't have a long-range anti-aircraft weapon.

   Originally completed with a battery of 533-mm torpedo tubes, these were deleted in later years and replaced by two single-cell launchers for the P-15 Termit (SS-N-2 Styx) anti-ship missiles, which were scavenged from retired missile boats. The Termit system proved unsatisfactory in the long run, allowing the Najins to carry only two missiles each, and in 2014 these weapons were replaced as well, with launchers for the 3M-24 Uran (SS-N-25 Switchblade) anti-ship missiles. The Uran is a 520 kg sea-skimming missile with a 145 kg HE-FRAG warhead, a high subsonic top speed, and an effective range of 130 km. It is unknown how many Uran missiles the Najin class can carry.

   The design of the Najin class has been noted as inherently dangerous, due to the location of the launchers for the missile launchers; missiles are launched directly forward from behind the conning tower with very little clearance from it, well aft on the ship, and should the missile drift (such as in a crosswind) or suffer an engine or booster malfunction, it is likely to collide head-on with the conning tower or the forecastle.

   The anti-submarine battery of the Najin class includes two RBU-1200 mortars. These launch a 73 kg rockets with a 30 kg warhead out to a range between 400 m and 1 200 m, which are effective at depths of up to 350 m. This system is also badly outdated, as it has to be reloaded manually, and there is no elevation or depression; the entire ship must be steered onto the target in order to hit it. While the RBU-1200 is capable of bombarding land targets as well, its short range and inability to train onto the target makes it less than ideal for this purpose. The Najin class frigates also employ both depth charge projectors, and depth charge rails. Thus, as with their other weapons, the viability of these ships in the ASW role is questionable at best. There also are provisions in place to carry 30 sea mines.

   Observation of the Najin class frigates has also proven to be an insight into the condition of the rest of the North Korean Navy, though not in a way that anyone probably expected. The Najin was photographed from the air in 1993 with a peculiar addition amidships, between the funnels; a vegetable garden. As this was during an infamous famine in North Korea (some sources suggest this famine has never fully subsided), it has been suggested the garden was created to compensate for a food shortage in the North Korean navy. It wasn't long before that image made its rounds in South Korea, leading to widespread ridicule of the FF-531 as being "organic" and "self-sufficient".

   The current status of the Najin class is uncertain, as FF-531 and FF-591 are seldom operational and are known to be in an advanced state of decay, due to poor construction standards and negligent maintenance practices. Thus, the recent modernization of FF-531 and FF-591 may well be more of a bluff than an increase in fighting power, as the North Korean government is infamous worldwide for such spectacles. Perhaps the status of the Najin class is not so much a question of how long they will be serviceable, as much as how long until they finally founder and sink while still in "active" service (which has actually happened to warships built to higher quality control standards than the Najin class, even after shorter service lives; the Argentinean D-2 Santisima Trinidad was a particularly grim example).

   Both vessels are still afloat, are occasionally seen underway, and are believed still be in service.


Name Laid down Launched Commissioned Status
FF-531 ? ? 1973


FF-591 ? ? 1975




   Article by BLACKTAIL

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Najin class

Najin class

Najin class

Najin class

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