of completed boats in warmer climates proved that the original Soviet refrigeration and air conditioning system designed for subarctic and arctic area was woefully inadequate for subtropical and tropical regions, so redesigns were needed to improve refrigeration and air conditioning systems, and all boats to be stationed in tropical and subtropical regions went through such a refit. In September 1969 construction of new Type 033s, with improved air conditioning and refrigeration capability, began at Huangpu Shipyard in Guangzhou, eventually, 13 units were completed. ES5A: Upgraded Type 033, with improvements mainly involving the replacement of equipment of Soviet origin with domestic Chinese systems, which includes: QZHA―10 (Type 779) attack periscope and QDYA―10 (Type 778) general purpose periscope. Addition of H/SQG-2 ranging sonar, Type 063 communication systems, and countermeasure systems. Domestic Chinese Type 801 sonar replaced the original Soviet MARS-24 sonar. The only difference between the Type 801 sonar and the MARS-24 sonar is that there are 24 transducer elements for the Type 801 as opposed to 12 in the original MARS 24, so the Chinese sonar had better accuracy. Domestic Chinese H/SQZ-D reconnaissance sonar (with Type 105 transducers) replaced the original Soviet system, the performance of the SQZ-D is almost identical to the original Soviet sonar it was developed from, except for the sector of scan, which is increased by 15 degrees. Additional noise reduction measures were also adopted. This is the type China originally sold to Egypt in the 1980s. Type 033G: Development of the ES5A, with the incorporation of the capability to launch acoustic homing torpedoes; analog computers installed to achieve automation of, and speeding up of, torpedo fire control calculations that were previously manually calculated. All Chinese Romeos were converted to this standard. The NATO reporting name for this type is rumored to be the Wuhan class. Type 033G1: A single Type 033G was modified to carry 6 YJ-1 (CSS-N-4) anti-ship missiles, this variant is called Type 033G1, with the rumored NATO reporting name of Wuhan A. The missile had to be fired while the boat was surfaced, with a total exposure time on the surface of less than 7 minutes. The most significant improvement, however, is the reduction of noise level by 12 dB. ES5B: Development of the Type 033G, primarily intended for export. This is an upgrade package for Romeo submarine users. The primary improvement of this class is the ability to launch wire guided torpedoes