Plan 1828 ocean surveillance ship

Plan 1828 ocean surveillance ship

3-view image of Girin in 2009, before refit
Class overview
Name:	Plan 1828 (Girin) class
Builders:	Samsan Shipyard, Haeju
Operators:	Menghe
Preceded by:	none
Succeeded by:	Plan 1850 ocean surveillance ship
Built:	2001-2007
In service:	2003-present
Planned:	3
Completed:	3
General characteristics
Type:	Ocean surveillance ship
Displacement:	1500 tons
Length:	65.2 m (overall)
Beam:	25.3 m (overall)
Draft:	7.6 m
Propulsion:	2-shaft integrated electric propulsion 4 diesel generators 2 electric motors (750 kW each)
Speed:	10 knots
Range:	3,000 nautical miles (5,500 km) at 8 knots
Complement:	12 officers 36 enlisted

Plan 1828 is the design designation for a type of ocean surveillance ship built in Menghe in the early 2000s. They are also sometimes called the Girin class after the first ship to be commissioned. They carry an experimental low frequency active sonar array and towed array sonar, and have greatly improved submarine detection capabilities compared to a conventional warship. Only three were built, with the class functioning mainly as a stepping stone to the larger Plan 1850 design which followed.

Design

The Plan 1828 design is the first Menghean military vessel to use a small-waterplane-area twin hull configuration. While structurally weaker than a conventional-hulled catamaran, the SWATH design offers greater stability in rough seas and a reduced acoustic signature. To further improve quieting, the class uses an integrated electric propulsion system, with four diesel generators in the above-water section powering electric motors in the submerged hulls.

The core feature of the Plan 1828 ships is the "Ilgi-gab" sonar suite. This consists of the Ŭ-808 low frequency active sonar and the Ŭ-515 passive towed array sonar. The Ŭ-808 consists of 20 sonar projectors spread out along a cable which is suspended between the twin hulls of the ship. It can scan in 360 degrees around the centerpoint, and the beam can be steered in angle to vary the depth. The entire array can also be lowered beyond its nominal depth, allowing the ship to search below the thermocline. It transmits in the 100-500 Hz frequency range. The Ŭ-515 listening array then receives echoes from this system and transmits them to the combat information center for processing. The Ŭ-515 array can also be used in a passive-only mode, to detect noise emitted by submarines.

Like ocean surveillance ships in other navies, the Plan 1828 (or Girin class) carries no meaningful armament. During the Innominadan Crisis, TŬG Bulsajo was spotted with 12.7mm machine guns on pintle mounts on the superstructure, but this appeared to be an improvised solution rather than a planned refit. Later, in 2016-2018, all ships in the class were refitted with Manhwagyŏng torpedo countermeasure launchers on either side of the superstructure. They remain highly vulnerable to attack.

Ships in the class

No standard nomenclature for experimental undersea surveillance ships (TŬG in Menghean nomenclature) existed when the Plan 1828s were ordered. On an ad-hoc basis, the Navy named the three vessels for mythological animals. The twelve ships of the Plan 1850 design would be named for animals of the Menghean zodiac.

Name	Meaning	Builder	Laid down	Launched	Commissioned	Status
Girin	Qilin	Haeju (Samsan)	2001 Sep 12	2002 Aug 24	2003 Nov 17	In service
Bulsajo	Phoenix	Haeju (Samsan)	2003 May 20	2004 Apr 08	2005 Feb 26	In service
Ryongma	Longma	Haeju (Samsan)	2005 Oct 03	2006 Sep 11	2007 Jul 30	In service