The Wave-class tankers are Royal Fleet Auxiliary "Fast Fleet Tankers" tasked with providing fuel, food, fresh water, ammunition and other supplies to Royal Navy vessels around the world. There are two ships in the class, RFA Wave Knight and RFA Wave Ruler. The ships were ordered to replace the ageing Ol-class tankers RFA Olna and RFA Olwen. The two vessels have seen service in a number of locations, including anti-drug and hurricane relief operations in the Caribbean, anti-piracy activities around the Horn of Africa and deterrent patrols in the South Atlantic.