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Displacement, tons: 375 standard; 392 full load Dimensions, feet (meters): 192.8 × 23.6 × 7.2 (58.8 × 7.2 × 2.2)

Initial input from Soviet advisers suggested an improved Kronstadt class (PLAN designation Type 6604) with a lower waterline and a shortened 52-meter Kronstadt-style hull. However, model testing revealed such a craft was not able to reach the required top speed of 28 knots. After a number of tests, a complete redesign produced a narrower and longer 58.8-meter hull with four Type 40II 2200 horsepower diesels was adopted. The new design’s top speed was increased from 24 knots to 28 knots.

Insufficient working space in the engine room was one of the more significant shortcomings in the Kronstadt design. To address this shortcoming, the engine room of the Type 037 was increased by moving the crew quarters forward four meters, thus making engine maintenance a simpler task. Some analysts suggested the Type 037 was an enlarged Soviet OS-1 patrol boat, a charge that Chinese designers rebuffed as China never imported any OS-1 boats.

The Type 037 hull was a very basic all metal construction with two levels. The lowest level contained the ammunition store, crew quarters, and engine room. The upper level housed the command, navigation, radar, and sonar rooms.

Its antisubmarine weapons package included four RBU 1200 5-tube fixed mortars with stabilizer and 2 racks of 9 each BMB-2 depth charges. The original Type VS-1 sonar was replaced by the Type SJD-3 sonar beginning December 19, 1976; however, there was no model designation change for the Type 037 as a result.

During the design phase, the single 85mm turret of Kronstadt was dropped in favor of two twin Type 66 57/70mm cannons. The Type 66 cannon was a navalized Type 59 57mm Anti-Aircraft Artillery (AAA) gun with a much greater rate of fire (270 rounds per minute to 12km) and greater accuracy but with reduced range than the Kronstadt’s tank-gun based 85mm (18 round per minute to 15km). This decision would pay dividends later in the 1974 naval clash with the South Vietnamese Navy, where two Hainan class (281 and 282) with two Kronstadt’s (271 and 274) were able to score direct hits in rapid succession against the four larger US-made warships at close range. The 127mm main guns of South Vietnamese US-made destroyer escorts were too slow for close range high speed combat in the atolls.

The PLAN called for utilizing the Soviet AK230 Twin 30mm automatic cannon as the secondary armament for the Type 037. However, due to design and production delays with the AK230, the already available Type 61 25mm/60 twin-cannon capable of firing 270 rounds per minute out to 3km was adopted instead.