USS Whitecap (SP-340) was a United States Navy patrol vessel in commission from 1917 to 1919. Whitecap was built in 1916 as a commercial fishing trawler of the same name by Manitowoc Shipbuilding Company at Manitowoc, Wisconsin. The U.S. Navy acquired Whitecap from the Bay State Fisheries Company of South Boston, Massachusetts, on 28 April 1917 for World War I service as a patrol vessel, and commissioned her as USS Whitecap (SP-340) on 8 May 1917.