A PT boat is a motor torpedo boat used by the United States Navy in World War II. These vessels were small, fast, and inexpensive to build, and were valued for their maneuverability and speed. However, PT boats were hampered at the beginning of the war by ineffective torpedoes, limited armament, and comparatively fragile construction that limited some of the variants to coastal waters. In the US Navy they were organized in Motor Torpedo Boat Squadrons (MTBRONs).