Flags flies over PT boat. In sea warfare since Pearl Harbor, the Navy tinset PT boats have frequently proved to be a deadly match for warships, submarines and merchant men. Their hulls are thin and their sides are small but their offensive and defensive armament is varied and effective. It consists of fifty caliber anti-aircraft machine guns, torpedoes and depth charges. These training pictures were taken at the United States Navy Motor torpedoed boat training center, Melville, Rhode Island. In their training, the tiny PT boat is learning to be constantly on the alert. In the background a crew member sighted the 50-caliber anti-aircraft machine gun while the officer in the foreground scans the sky for planes