In October 2017 the South Korean Navy received the first of at least twelve PKX-B patrol boats. These are a smaller (230 ton) version of the larger (570 ton) PKX-B that first appeared in 2008. This sort of evolutionary development of new ship classes has become common with new South Korean warship designs and the South Koreans often “evolve” their designs that is the case in other nations. It works. The PKX-B is smaller because of technology and a new guided missile specifically designed to deal with North Korean “swarm attacks” of smaller boats armed with missiles or torpedoes. While the PKX-B was a result of the 2010 attacks by North Korea (that sank one South Korean corvette and the shelling of a South Korean island off the west coast) the first PKX-A entered service in 2008 based on the need to replace older 170 ton patrol boats that were worn out and forced to retire because they were no longer safe to use.
In 2011 South Korea has increased its order for PKG-A missile patrol boats from 24 to 34. That was later changed to 18 PKX-A boats and a dozen or more PKX-B boats. All 18 PKX-A boats are now in service. These are 63 meters (207 foot) long, 570 ton vessels with a top speed of 76 kilometers an hour. Each boat is armed with a 76mm gun, a dual barrel 40mm autocannon, shoulder launched anti-aircraft missiles and four anti-ship missiles (range: 150 kilometers). In addition to air and surface radars, there are also electronic countermeasures. There is no sonar or anti-submarine weapons. There is a crew of forty, and each boat costs $39 million.
The PKX-B are 44 meters (144 foot) long, 230 ton vessels with a top speed of 74 kilometers an hour. Each boat is armed with a 76mm gun, two 12.7mm RWS (remote weapons station) machine-guns, shoulder launched anti-aircraft missiles and twelve 130mm anti-ship missiles (range: 3-20 kilometers). The 80 kg (176 pound) missiles are initially guided by GPS/INS to the general area of the attackers by the ships fire control system and make their final attack with a heat-seeker. The fire control system for the 130mm missiles can handle three targets simultaneously followed by another volley of three missiles. In addition to air and surface radars, there are also electronic countermeasures. There is no sonar or anti-submarine weapons. There is a crew of twenty, and each boat costs “somewhat more” than the PKX-A. The first four PKX-B will be in service by 2019 and another four by 2020.
The PKX boats replaced the popular Chamsuri-class patrol boats. These first entered service in the 1970s and over a hundred were built, most for South Korea but fifty ended up being exported. Chamsuri had no missiles, only a 40mm and two 20mm autocannon and two 12.7mm machine-guns. These were adequate for decades but in the 1990s it became clear that anti-ship missiles were needed for the next class of patrol boats. That led to the still evolving PKX class.