The Hecla class formed the backbone of the Royal Navy's ocean survey fleet from the mid-1960s. Three ships, HMS Hecla, HMS Hecate and HMS Hydra, were ordered in the early 1960s to replace the aging survey ships HMS Scott and HMS Shackleton. Hydra was sold to Indonesia in 1986 and renamed Dewa Kembar; Hecate decommissioned in 1990 and was broken up, while Hecla paid off in 1997 and was sold to an Irish private company, to be replaced by HMS Scott. Herald was finally decommissioned in 2001, and was replaced the same year by HMS Echo.