Empire Ace was a 275-ton tug which was built in 1942 for the Ministry of War Transport (MoWT).

Empire Ace was built by Cochrane & Sons Ltd, Selby as yard number 1255.

In 1961, Diligence was transferred to the Ministry of Defence and reverted to Empire Ace.

Empire Ace was refloated in June 1969 but declared a constructive total loss.

Empire Ace had the UK official number 1690781 and call sign MFLY.