Plan 805 submarine chaser

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DChS Plan 805 1982 2022-11-04.png
DChS-2051 as commissioned, 1982
Class overview
Builders:
  • Hwasŏng Nampo Military Shipyard
  • Insŏng Dongpo Military Boat Yard
Preceded by: Plan 145 submarine chaser
Built: 1980-1990
In commission: 1982-present
Completed: 38
General characteristics
Displacement: 440 tonnes
Length:
  • 49.7 m overall
  • 46.0 m waterline
Beam: 8.84 m
Draught: 2.73 m (keel, full load)
Propulsion:
  • 4 × diesel engine, 4,000 shp each
  • 4 shafts
Speed: 33 knots
Range: 2,000 nmi (3,700 km) at 14 kts)
Complement: 74
Sensors and
processing systems:
  • 1 × HRDJ Type 75 radar
  • 1 × Tosan sonar
Armament:
  • 2 × 2 30mm AK-230 CIWS
  • 2 × 5 210mm ASW rocket tube (HBDJ-21/5)
  • 4 × 1 400mm torpedo tube

The Plan 805 submarine chaser is a type of small patrol ship built in Menghe during the 1980s. In the West, they are most commonly identified as submarine chasers or corvettes; in Menghe, they were first built as small anti-submarine patrol ships, but reclassified as coastal anti-submarine patrol ships in 1995. In the mid-2000s, they were rebuilt as anti-saboteur patrol ships, while retaining the DChY hull designation.

Description

The Plan 805 submarine chasers are built on a steel planing hull to allow increased speed when responding to surface or sub-surface contacts, and are powered by four G506 engines developing 4,000 shp each. Diesels were chosen over turbines out of affordability concerns, as these ships were to be designed and produced entirely within Menghe at three less developed shipbuilding sites. This made them somewhat faster than the Plan 145 submarine chasers, though they were still limited to 34 knots.

The only sonar equipment carried by the Plan 805 submarine chasers as built was a teardrop-shaped hull sonar. This was mounted on a retractable arm which could extend it 1.5 meters away from the hull, separating it from flow noise and turbulence to improve its sensitivity. A small domestic Menghean design, this sonar was not particularly powerful or sensitive under ideal conditions, and at even moderate speeds flow noise was still sufficient to blind it. Anticipating this, the designers fitted these ships with two D-104 datalinks, which allowed an aircraft, surface ship, or coastal datalink station to relay target coordinates to the submarine chaser in real time. An HRDJ Type 75 I-band radar on the main mast provided some additional anti-submarine capability by detecting raised periscopes and sensor masts within a 20-kilometer radius, though this system was vulnerable to jamming and often returned false positive contacts.

Anti-submarine armament consisted of four torpedo tubes on the quarterdeck, fixed in position at an angle of 30 degrees off the bow. These fired 400mm acoustic homing torpedoes, the same type used by the Banjihwa-class corvettes. Two HBDJ-21/5 anti-submarine rocket launchers in fixed, forward-facing positions provided additional short-range engagement capability. Self-defense armament consisted of two AK-230 twin 30mm autocannons controlled by an aft-facing MR-104 radar (refitted to an MR-123 on some ships) and a forward-facing manual gun director.

Operators