Joined HMS Sirius 23 Mar 1787 at Portsmouth, age 28 years, crew number 183, with previous service per Ganges. Cavanough is said to be the first person to set foot ashore at Port Jackson as he secured the long boat, on the morning of 26 Jan 1788. It is not known if he was a member of the party that visited and camped at Port Jackson and Sydney Cove between 20 and 22 Jan 1788.

Cavanough was stranded on Norfolk Island in Mar 1790 after the shipwreck of HMS Sirius. In Feb 1791, returning to Port Jackson per HMAT Supply, officially dismissed from HMS Sirius books on 7 Mar 1791 and returned to Norfolk Island as a seaman settler per HMAT Supply 19 Mar 1791.

More Details on Owen Cavanough and his family with Margaret Darnell/Darling, convict Prince of Wales 1788 are in:

• Marriages November 1791 Norfolk Island: Romance among the Pine Trees
• Settlers and Landholders Norfolk Island 1793
• Turtle Bay Burial Ground Norfolk Island