HMAS Sleuth was a patrol boat operated by the Royal Australian Navy (RAN) during World War I. Built in 1901 by William Alfred Dunn at Berrys Bay, Sydney, as the steam yacht Ena for Thomas Dibbs, Commodore of the Royal Sydney Yacht Squadron. Ena was purchased by the RAN in January 1917 for use as an auxiliary patrol vessel. She was fitted with a QF 3 pounder Hotchkiss gun on her bow and a searchlight. She was commissioned on 13 January 1917 as HMAS Sleuth and served as a patrol vessel along the Queensland coast and as a tender to the Training Ship Tingira.