The summer of 1917 provided few opportunities for "Wainwright" to test her sub-killing techniques. On 4 July, a member of the destroyer's crew spotted a purported periscope and soon thereafter others claimed that a torpedo was reported to have passed the ship, astern. "Wainwright" depth-charged the last indicated position of the undersea raider but to no avail. On the morning of 20 August, after brought up some oil with one of her depth charges, "Wainwright" dropped a couple of depth charges as she passed through the faint slick. A few minutes later, she joined other ships in some sporadic gunfire but failed to prove that a submarine was in the area.