There was a pressing need to replace the ageing cruiser Royalist and the RNZN's last two operational Loch-class frigates, which carried outdated sonars and anti-submarine weapons and were slow.

[2] Additionally, Cold War tensions were high in the aftermath of the Cuban Missile Crisis with escalating trouble in South East Asia over Vietnam and Indonesia's infiltration into Malaysia and Borneo, led the government to order a third Type 12.

[citation needed] Laid down in January 1964, Waikato was constructed by Harland and Wolff and was delivered in 1966, commissioning into the RNZN in September that year.

[citation needed] In terms of armament, Waikato was a fully armed Batch 2 Leander, with Mk 6 twin 4.5-inch guns, a Seacat GWS22 point defence missile, Limbo anti-submarine mortar and Wasp helicopter.

She was identical to the Royal Navy Leanders of her group, with 965M LRAW and 177 hull and 199 Variable depth sonars, while her half sister, HMNZS Canterbury was a larger improved Leander, completed in 1971, with a more automated and remote controllable steam plant, a frigate potentially capable of updating with long range bow sonars and Seawolf missiles.

[4] For the first nine years of its RNZN service Waikato operated around New Zealand and with the ANZUK naval squadron based at Singapore, which continued in reduced form in 1971–75 with the Royal Navy sending 5 or 6 frigates and destroyers.

During the forenoon a Russian fishing vessel well to the south of New Zealand called for assistance for a critically injured seaman and Waikato altered course and increased speed to get within flying range.

The vessel was finally located 60 miles from its reported position the following afternoon and with considerable difficulty the sailor was winched off the ship and taken on board, to be flown to hospital at 3.30 am the next morning.

Some crew believed the frigate and its personnel were endangered by landing a large chopper never before tested upon Leanders and the order was officially noted.

[13] Waikato alternated with HMNZS Canterbury on these duties, the frigates visiting Colombo, Karachi, Mauritius, Zanzibar, Port Sudan, Muscat, Oman and Diego Garcia[14] on what was officially known as the Indian Ocean Patrol.