The Nasty type patrol boats were a series of fast patrol boats designed and built in Norway during the 1950s and '60s for the Norwegian, and other, navies. The prototype, Nasty, was designed and built in 1957 as a private venture by Westermoen of Mandal, Norway.Following this Westermoen received orders from the Royal Norwegian Navy (for whom they were known as the Tjeld-class), and from the navies of the United States, (who called them the Nasty class), Greece and West Germany. Six vessels were also built in the United States under licence (some parts, such as the keel and stem being imported). A total of 50 vessels were constructed of this type during the 1960s and served in five different navies.