 Wainwright reported her first scrape with a German submarine on 11 May . She sighted an abandoned lifeboat at about 08 : 00 . After investigating the drifting boat for occupants and finding none , she sank the boat with gunfire . At about 08 : 15 , a lookout reported that a torpedo had missed the destroyer some 150 yards ( 140 m ) astern . Wainwright then fired several rounds from her 4 @-@ inch ( 102 mm ) guns at what was thought to be a periscope . The supposed submarine disappeared soon thereafter ; and , despite a thorough investigation of the area , the destroyer could turn up no more evidence of the presence of a U @-@ boat . 
