HMNZS Manuka was one of three composite New Zealand-built Castle-class trawlers commissioned by the Royal New Zealand Navy during World War II.

The vessel was ordered after the New Zealand government, facing a requirement for more minesweepers to operate in home waters, chose the Castle-class design because it was simple enough to be built with the country's limited ship construction facilities at the time.

[1] Manuka was laid down on 21 October 1940 and was of a composite design, using Kauri wood due to a shortage of steel at the time.

In 1946, Manuka was leased to the Chatham Island Fishing Company, under the condition that she would only be used in New Zealand waters, and that she would be given back to the navy in case of an emergency.

[7] In 1950, Manuka was moored in Port Hutt, acting as a floating freezer, with local trawlers storing their catches onboard.