Durjoy-class patrol craft

The Durjoy class is a class of large patrol craft of the Bangladesh Navy. A total of four are serving the Bangladesh Navy as of 2021.

History
The Durjoy class is a class of large patrol crafts of the Bangladesh Navy, designed to meet the longer patrolling and surveillance needs in the vast EEZ of Bangladesh in the Bay of Bengal as well as to perform limited offensive roles. The ships of this class are of two variants, anti-surface warfare variant and anti-submarine warfare variant. The primary characteristics of the two variants are same but they differ in armaments and sensor suite.

Initially, a contract was signed in 2009 for two ships to be built at Wuchang Shipyard in China. The ships were of anti-surface warfare variant. The first, BNS Durjoy (P 811), was launched on 26 August 2012, while the second, BNS Nirmul (P 813), was launched on 27 September 2012. Both ships arrived in Bangladesh in February 2013. The ships were commissioned on 29 August 2013.

On 30 June 2014 the Bangladesh Navy signed a contract for the next two Durjoy-class vessels with Khulna Shipyard. These ships were constructed in Bangladesh under ToT from China. Keel laying of the ships was done on 6 September 2015. The first two vessels made at Khulna Shipyard were commissioned on 8 November 2017. These ships were of Anti-submarine warfare variant.

Design
These ships are 64.2 m long, 9 m wide and have a 4 m draught with a displacement of 648 tonnes. The ships have a bulbous bow shape, which suggests they are designed to sustain heavy sea states. The ships have speed and range to support long missions. The large patrol crafts are powered by SEMT Pielstick 12PA6 diesel engines driving three screws for a top speed of 28 kn for anti-surface warfare variant and 25 kn for anti-submarine warfare variant. The range of the ships is 2500 nmi for anti-surface warfare version and 2000 nmi for anti-submarine warfare version with an endurance of 15 days. The anti-surface warfare ships can carry 60 personnel while anti-submarine warfare ships can carry 70 personnel. They can carry one Rigid-hulled inflatable boat and has the support system to launch it.

Electronics
The primary sensor of these ships is a SR47AG surface and air search radar.The ship carries a Chinese TR47C fire control radar for main gun. The ships also have an ESS-3 bow mounted sonar with an effective range of about 8000 m for underwater detection. A JRCSS combat management system (CMS) with at least three multifunction consoles is also fitted in the ships. The primary sensor of these ships is a SR47AG surface and air search radar. They carries a Chinese TR47C fire control radar for main gun. For navigation, the ships use the Japanese JMA 3336 radar. To help the navigational radar, the Vision Master chart radar is used. These ships have an ESS-2B bow mounted sonar with an effective range of about 8000 m for underwater detection.
 * Anti-surface variant
 * Anti-submarine variant

Armament
The large patrol crafts of this variant are armed with a 76.2 mm H/PJ-26 naval gun and four C-704 surface-to-surface missiles (SSM) mounted aft. Besides, these ships have two dual Oerlikon 20 mm cannon mounted amidships which can be used for anti-aircraft role. For ASW role they have two forward-mounted 6-tube EDS-25A 250 mm ASW rocket launchers and decoy launchers.
 * Anti-surface variant

The ships of this variant uses a Chinese origin single 76.2 mm NG 16-1 naval gun as the primary gun. Besides, they have one CS/AN2 30 mm single-barrel naval gun mounted amidships used as the secondary gun. For anti-submarine warfare role, these ships are armed with two triple 324 mm torpedo tubes for ET-52C torpedo. This torpedo has a range of 9.4 km and speed of 42 knots.
 * Anti-submarine variant