North Korean Small Submarines File

Download an Google Earth Placemarks file containing lots of DPRK subs HERE
Reproduced and expanded with permission of another blogger who closed his site.

This is to be a working file for North Korean Navy and exported small submarines. The file will grow slowly so check back regularly if you are interested in the topic. We are always particularly grateful to all those who have provided information that furthers this research.

DPRK export submarines are particularly interesting as they offer rare insight into North Korean types. Iranian IS-120 Ghadir submarines are particularly useful in this regard and are interesting in their own right.

MS-29 Yono (Yeoneo)
Displacement: 115 - 130 tons surfaced
Length: 29m
Width: 2.75m (hull)
Powerplant: Diesel-electric with folding snort mast. Single diesel.

The recent sinking of a South Korean warship Cheonan has brought more details of DPRK's midget submarine fleet into the public domain. Reliable information about the MS-29 Yono ("Yeoneo") class submarine comes from captured Sang-O crewman Lee Kwang Soo, interviewed by South Korean blog Daily-NK ( http://www.dailynk.com/english/read.php?cataId=nk02500&num=6445 ).

Lee describes it as a modified Yugo class. The displacement is significantly greater than the basic Yugo class, and represents an enlarged P-4 class boat with other modifications. The export version is known as IS-120 which has been exported to Iran.

The externally mounted torpedoes are described by the former DPRK submariner. Older variants of Yugo boat with externally mounted torpedoes were already known, so there may be some mix-up in translation. Lee cites quite launch, whereby the torpedo 'swims' away under its own power rather than being forcible ejected from the torpedo tube (which is noisy and may alert the target to the launch) as the motive for this arrangement. This is plausible of course and is not unique among small submarines. The disadvantages of course are performance and weapons maintenance.

It should be noted that the previously captured 'P-4' boat clearly had design adaptions for two internally mounted torpedo tubes, and the IS-120 'Ghadir' class operated by Iran also has internally mounted tubes.
Careful inspection of available images shows slight differences from exported IS-120 submarines in service with Iran. The two submarines are however closely related and the IS-120 can be viewed as an export model of MS-29 and may reflect later model Yonos in DPRK service.

It therefore seems probable that there are two or three sub-versions:
a) with twin internal tubes as per export boats
b) without tubes, equipped with diver lock-out
c) with external tubes. Possibly fitted to infiltration version (b) above


Yugo
Dimensions: L 20m, W 2m, Displacement 90t (submerged)
Speed : 10kts surfaced, 4 kts submerged
Armament: 3 configurations:
a) 2 x533-mm externally-mounted torpedoes in drop gear
b) 2 x middleweight (400mm?) torpedo tubes internally mounted in nose. arranged vertically.
c) None in infiltration variants.

A generic name for early midget submarines based on Yugoslavian plans supplied in 1965.

Original Yugo class boats likely retired but evolved Yono and P-4 classes still likely operable.

Yugo class with externally carried torpedoes

The Yugo boats have room for 4-6 infiltrators and can carry torpedoes or mines for the attack role. They are relatively short ranged though so for infiltration (or attack in wartime) operations in the far south, off Japan or further away, they require transportation and launch from a mother ship.

Yugo class with internally mounted middleweight torpedo tubes

The ships were built at Yukdaeso-ri shipyard on the west coast from the late 1960s through to the early 1980s at which time they were superseded by the generally more capable Sang-O type. Contrary to some sources, the North Korean Yugo submarine was not very similar to Yugoslavian operated midget submarines such as the impressive Velebit type.






41m Boat
In the early 1980s North Korea developed a much larger coastal submarine known, rather imaginatively, as the “41m boat”. No prizes for guessing the length of this submarine. It is not clear exactly what the boat looked like except that its sail is not unlike the Yugo’s in profile and that it was not a “teardrop” hull. The type does not appear to have been successful and only one is reported and it is unlikely to still be operable.


'Sang-O' type

Dimensions: L 34m, W 3.8m, Displacement: 370t (submerged)
Power: 1 diesel, 1 electric motor, 1 shaftSpeed 7.2kts surfaced, 8.8kts submerged
Range: 1500nmMax Depth: 150 meters Crew: 15
Armament (attack sub): 4 x 533-mm torpedoes with no reloads (Inc Russian 53-65 ASW torpedoes)Armament (recce/infiltration version): None. 5 infiltrators and 6 KWP Reconnaissance Bureau Cadre as passengers

Developed as a much improved follow-on to the Yugo type, the Sang-O is well known because one was captured by the South during a botched infiltration mission in September 1997. The Sang-O is much larger and longer ranged than its predecessor. Some boats have the torpedo tubes replaced by a passenger space and diver swim-out door for infiltration and sabotage missions. The 1500nm range is useful enough to allow the boats to operate without a mother ship in most cases making them much less susceptible to detection. Hypothetically these subs could be modified to carry anti-ship missiles or Shkval rocket-torpedoes but neither capabilities are reported.

'P-4' type

Dimensions: L 29m, Displacement: 190t
Armament: 2 x 533mm (21’’) torpedo tubes (not fitted in infiltration version)

An improved "Yugo" midget submarine design, the P-4 is smaller than the Sang-O but also seemingly more advanced. It features an unusual co-axle twin propeller consisting of a large skewed propeller and a much smaller conventional propeller; this arrangement is believed to be an attempt to reduce the submarine’s noise signature.

An example of this type of submarine was captured during an infiltration mission in 1998 and subsequently put into service with the South Korean Navy emphasizing the build quality of the boat. It was recently taken out of service and put on public display at the war memorial. Interestingly the sensors of the captured boat, including the sonar, were of Japanese origin.

IS-120 'Ghadir'
IS-120 is the export designation of the MS-29 Yono. The only country thought to operate it is Iran, who has at least 4 in service and is locally producing it. As per other DPRK submarine types Yono is a family of submarines with many differences, some slight and some more obvious, between models. Iranian IS-120s are widely photographed and filmed thus giving the best open source insight to date on the Yono class.

In simple terms the Iranian IS-120s are an MS-29 boat with additional sonars and a mast sensor/communications fit very similar to the captured P-4 type.

Source: IRNA

Delfin
Appears to be a variation of the Yugo type, this mystery submarine is in service with Cuba. Very little is known of its operational service, numbers or details. Reports also suggest that it is related to the Sang-O class but this seems improbable given its external appearance and other factors of descriptions. May be constructed in Cuba. Artist's impression based on the Yugo form:

A lead provided by Lee Kwang Soo is that some Cubans have inspected North Korean submarines and may have purchased some in 1990s. This ties with the 'mystery' Cuban midget submarine photographed in Havana and previously included in Fortress Cuba


The sub is quite different from other DPRK submarine designs such as P-4 and Sang-O but may be another unreported type.

Viet P-4 ('Yugo')

2 P-4 type midget subs supplied in 1997 and are operated by submarine unit M96. The deal included 16 torpedoes, 282 batteries and 8 mines. Although the torpedo type is not reported they are known to be of 1960s Soviet type, probably Type 53-56.

It is likely that the exact model is very close to DPRK-service P-4 although they are generally (not widely, their existance is not well known) referred to as "Yugos", a reference to the original Yugos which would have been second-hand at this time - as a rule DPRK exports new submarines. Some observers misidentify them Sang-O in Vietnamese service. The P-4 is substantially smaller than the Sang-O.

Video still of P-4 on Vietnamese TV (via Vietnamese internet community)

Not all of the equipment sold (torpedoes, batteries, mines) was new and Vietnam had to replace it with Russian source units. Google Earth imagery suggests 20-25m design rather than larger but otherwise similar Yono/IS-120 type:

Narco submarines, torpedoes and semi-submersibles

This is likely to be an ongoing project to catalogue and illustrate Latin American narcotics SPSS' (Self-Propelled Semi-Submersibles) so if it appears incomplete when you visit, please consider checking back occasionally for added material. We are looking at these boats from an equipment standpoint - for fuller histories and info on the narcotics trade there are lots of sources out there. These are not military units but relevant to the topic of covert naval equipment in general, and certainly of interest to the authors. Each craft is built to order in jungle factories and unique, but certain themes and techniques hold true. Exact data is hard to obtain.

There are many ways to categorize, divide up and "slice and dice" these craft. From an evolutionary standpoint there have been three phases:

• 1992 - 2004 Experimentation through trial & error.


• 2005 - 2006 Rapid prototyping and increases in capability. Development and use of SPSS.


• 2007 + Mature designs with greater standardization

Additionally these craft can be divided by type:

Type 1: Fully Submersible
- Type 1A: Submarine with self propulsion etc. The most advanced and consequently expensive to create type. These are very rare although a handful have been captured. There doesn't seem to be any evidence of successful operation of this type but analysis of circumstantial evidence suggests that these are increasingly employed.
- Type 1B: Towed 'Torpedo' - covert transportation canister towed by disguised vessel.

Type 2: Semi-submersibles capable of ballasting down to lower their surface profile, and controlling their running depth, but not fully submerging. These are also very rare with only a few ever captured.

Type 3: Low-profile vessels (LPV), which are often misdescribed as "semi-submersible" and constitute the vast majority of these vessels to date. Simply a boat designed to run awash to minimize radar cross-section.

A brief chronology of major discoveries
Not exhaustive.
1992 - Colombian Navy begins to detect modified speedboats and semi-submersibles. Typically built out of fiberglass with 1 to 1.5 tons capacity.
1994 - More elaborate submersible design with radar, a depth meter and an internal oxygen supply captured in Tayrona Park, Columbia. Capacity still around 1 ton.
1994 - Half built submersible captured in Turbo, Columbia.
1995 - Incomplete submarine captured in Cartagena, Columbia. Much more capable design.
2000 - half-built very advanced submarine captured at Facatativa, Columbia.
From 2001 to 2004 there was a significant gap in captures. It is likely that there was very little SSPS activity in this time.
March 2005 - Low profile boat captured in Tumaco, Columbia. Very little press coverage outside Columbia - only craft captured that year.
March 2006 - Large low-profile boat captured on River Timbo near Pital, outside Buenaventura, Columbia by Marine Riverine Infantry Brigade Nr.2.
November 2006 - US forces capture a low-profile boat, dubbed Bigfoot-1.
August 2006 - Spanish police capture a fully-submersible narco sub off Galicia, Spain. The craft was locally built in Spain and in design terms unrelated to Colombian examples.
August 2007 - Large low profile boat captured in Guajira on Columbia's Caribbean coast
November 2007 - Low profile boat captured near Buenaventura in Columbia. Close resemblance to Guajira boat but single engine/screw.
2007 - 'Narco-Torpedo' type craft start to be captured
2008 - US forces capture a second low-profile boat similar to earlier 2005 Tumaco boat. Dubbed Bigfoot-2.
May 2010 - Low-profile boat captured in Ecuador
June/July 2010 - Large (30m) Submarine captured in Ecuador

Example Fully Submersible craft...

1994 Tayrona Submarine
L <10m

A small boat, made of wood and fibreglass captured in Tayrona, Columbia in 1995. Found to be unstable when tested by authorities. Fit for shallow submergence only with depth controlled by lead weights externally mounted on lower hull. Had advanced communication and navigation equipment.

1995 Cartagena submarine
L 11.7m, W 2m
Capacity 1.5 tons

As the name suggests, this craft was captured in 1995 at the northern coast port of Cartagena in Columbia. This submarine is relatively advanced in some respects with a cylindrical steel hull suggesting the intention to operate it at deep depths relative to the fibreglass boats. Although unfinished, it is not clear how depth was to be controlled - the lack of ballast tanks or the water inlets/outlets associated with them suggests maybe lead weights were to be used as per the 1994 Tayrona boat.

Facatativa Submarine‏
Discovered by Colombian police in Cartagenita/Facatativa in September 2000.
Type 1A Submarine
L 30m, W 3.5m
Capacity - 15-20 tons

Upper sketch shows the craft as discovered, lower sketch shows approximate finished configuration.

By far the most advanced design captured to date, this appears to be the work of Russian advisers and has many features similar to real military diesel-electric submarines. The boat was to be 'double hulled' with a single shrouded screw. Crew is thought to be up to 12 persons. Construction cost is estimated at 10 million USD.

If completed this sub would have been capable of extremely long ranged missions and would have operated similarly to a military submarine.

At 30m long the Facatativa boat is about the same size as an MG-110 or IS-120 military midget submarine. The Facatativa boat has a greater internal volume that either of these boats with a larger diameter pressure hull. The pressure hull also appears to extend almost the full length of the boat, maximizing storage space. The narco sub would likely have depth sonar, satellite comms, GPS and a navigation radar - advanced stuff but not comparable to the military boats. Additionally as a cargo carrier the Facatativa boat does not have torpedo tubes or it seems diver lock-out facilities.

Size progression, approximate scale:

2006 Vigo

L - 11m, W - 3m

Load: 1 ton

Captured by Spanish Police on the Atlantic coast, this submarine is thought to be locally produced and not closely related to the Colombian subs in design terms. The boat is made from steel with ballast tanks on the flanks. An interesting design feature is the use of separate props for the diesel (main) and electric drive. The craft was likely intended for short transits between the cargo ship and shore.

2010 Ecuador 30m Sub

L - 30m, W - 3m

A large fibreglass submarine, with diesel-electric drive and twin screws. The construction limits it to shallow submergence, but it is clearly designed for underwater operation. The lower hull on the attached sketches is speculative. The pilot windows in the base of the sail are very similar to the cockpits of recent low-profile boats. The boat was painted in multi-tone camouflage.

Nacro-torpedo
Designed to be even harder to detect than low-profile boats, but cheaper than proper crewed submarines, the 'torpedo' is towed behind a boat (disguised as a fishing, commercial or leisure craft) at a depth of about 30m. The torpedo is released if the authorities approach, and discharges beacons after a set period of time to allow recovery by a back-up boat after the authorities have left the area.

Example semi-submersible boats....

1993 San Andres semi-sub
L (approx) 7m
Capacity 1 - 2 tons
Crew 2

The only true semi-submersible captured to date, this early type was constructed largely of wood and fibreglass.

Steel LPVs
L - 18m, W - 3.1m

Example captured in Feb 2008. At least one very similar craft (almost certainly a 'sister-ship') scuttled during capture since. Distinct from other low-profile boats in capability to trim running depth via hydroplanes at rear. Possibly equipped with internally water ballast to further assist. Much lower profile than most low-profile boats with nose completely submerged even in calm seas. Metal construction implies re-use, relative to the one-way M.O. of most fibreglass craft. The faceted hull form does not offer deep-diving capability as would a cylindrical pressure-hull found on a true submarine.

This second example has slightly different piping, but is otherwise similar.


Example low-profile boats....
Earliest craft
The first low profile boats amounted to a sealed 'go-faster' boat which rode lower in the water. Typical arrangement had cabin at rear and cargo hold amidships.

Between 2001 and 2005 there seems to have been a sharp drop in activity, then in late 2005 low profile craft started to be captured again. Over time the above configuration has given way to a more specialised hull form with generally pointed bow and stern, with tiny cabin amidships with engine compartment rear and cargo in every available space. Features like sloping sides to the cabin suggest radar stealth, but other features contradict this design consideration - stealthiness is primarily provided by simply being low in the water and being largely fibreglass.

2006 Pital capture
L - 18m, W - 3.8m
Load: 4 tons

This craft is unusual for its twin engine, twin prop arrangement, but otherwise is a generic low-profile design. The craft was captured in March 2006 near Pital on the River Timbo outside Buenaventura, Columbia.

'Bigfoot-1'
So-called because "narco-subs" were widely reported but within the US military no-one had actually caught one. That changed with the capture of a low-profile "sub" in November 2006. US forces had seen the earlier craft captured by the Colombians so the design was not that unexpected. Bigfoot-1 is quite different in shape to the more common hull design (typified by Bigfoot-2), having a rounded hull, but it is not unique in this characteristic either.

2007 Guajira low-profile boat
L - 20m, W - 3m
Load: 10 tons

Although narrower than the Bigfoot-2 type and only slightly longer, the rounded cross-section of this craft gives it a much larger internal volume and load capability than most other low-profile boats. The design is twin engine with twin props. Although unconfirmed, some believe this boat may have been built for longer distance trips from Columbia to Europe or Canary Islands from where the load could be transferred to vessels waiting offshore.

A remarkably similar boat was captured a couple of months later, suggesting the same designer:

'Bigfoot-2'
Captured by US forces 2008. Often described as "Semi-Submersible" but fitting our Type-3 Low Profile classification system in actual capability.
L - 18m, W - 3.66m

Load: 6.4 tons

Other recent low-profile boats

Nacro-Sub very similar to Bigfoot-1, captured in July 2007 off Columbia's Pacific coast.

Nacro sub generally similar to Bigfoot-2