When the Admiralty asked New Zealand to expand its training facilities on 9 September 1940, a new training establishment became imperative. There was no longer sufficient land at the Devonport Naval Base for both the Naval Base and a training establishment. On 11 December the Navy received Cabinet approval to occupy the old quarantine station at Motuihe Island in the Hauraki Gulf. The station was commissioned as HMS TAMAKI on 14 January 1941.
Training began almost immediately, with 178 men under training and a ship's company of 42. A building programme designed to give TAMAKI a training capacity of 600 'hostilities only' men a year and 120 'continuous service' ratings was initiated, and completed within 18 months. By the end of 1943, over 1,000 men were being trained annually. Of the 10,000 men who served in the RNZN and RNZNVR 6,000 passed through TAMAKI.