The Nasty class of fast patrol boats were a set of 20 vessels built for the United States Navy to a Norwegian design and purchased in the 1960s for covert operations during the Vietnam War.Following World War II the US Navy had little use for fast attack craft, and most of her PT boats were disposed of shortly after VJ Day.With the involvement in the Vietnam War the Navy saw a renewed need for small combatant craft for "brown water" operations, and they approached the Norwegian Westermoen company, which had built a prototype fast attack boat, the Nasty, and was currently building a set of 12 vessels (the Tjeld-class patrol boats) for the Royal Norwegian Navy.With the end of the conflict the need for these boats evaporated, and the high maintenance costs of such vessels militated against retaining them.Most were disposed of in the 1970s and all were gone by 1981, except for PTF 17, which is on display at the Buffalo and Erie County Naval & Military Park.