Minesweepers of the Royal New Zealand Navy

Naval trawlers were trawlers purpose built to Admiralty specification to operate as minesweepers and/or anti-submarine boats.

Thirteen Castle-class naval trawlers were commissioned. Apart from James Cosgrove and Wakakura, all were built in New Zealand by government directive, circa 1942. They were 135 feet (41.1 m) long, displaced 540 tons standard or 612 tons loaded, and were designed for a complement of 27. The three-cylinder engine of 480 indicated horsepower (358 kW) from A & G Price of Thames gave a speed of 10 knots (19 km/h). The coal-fired boiler was of the Scotch marine type. The boiler size governed the size of ship that could be manufactured, and as boiler plate of the required size was not available, two completed boilers and some partly completed boilers were supplied from Britain.[1]

In addition two further Castle trawlers, Tawhai and Waikato, were completed in 1946 but were not commissioned.

The Bird-class naval trawlers were 168 feet (51.2 m) long, displaced 923 tons full load, and could manage 13 knots (24 km/h). They had a complement of 33–35 and were armed with one 4-inch (102 mm) gun, two Hotchkiss guns in single mounts, twin Lewis guns and 40 depth charges. They were equipped with asdic.

The Isles-class naval trawlers were 164 feet (50.0 m) long, displaced 740 tons full load, and could manage 12 knots (22 km/h). They had a complement of 40 and were armed with one 12-pounder gun, three 20 mm Oerlikons in single mounts and depth charges.

These vessels were usually armed with a quick-firing 4-inch (102mm) or 3-inch (76mm) gun on a raised bow platform, some machine guns, and depth charges. Vessels used for minesweeping were also fitted with minesweeping and mine handling equipment.

These ships were usually armed with a quick-firing 4-inch gun, machine guns and autocannon. Vessels used for minesweeping were also equipped with the appropriate equipment.

Wiliam Halsey sworn in as ComSoPac in November 1942

COMSOPAC is an acronym for Commander South Pacific. During World War II, one of the major United States theatre commands was the command of the South Pacific Area. This command was usually referred to as COMSOPAC (COMmander SOuth PACific)

It was formed in April 1942 as a subordinate command of Pacific Ocean Areas, commanded by Robert L. Ghormley through October 1942, William Halsey, Jr. to June 1944, John H. Newton to March 1945, and William L. Calhoun to the end of the war.

In June 1942 New Zealand passed the operational control of most of its South Pacific naval forces to COMSOPAC. This continued until COMSOPAC released control in June 1945.

The headquarters for COMSOPAC were initially located in Auckland, New Zealand. In July 1942 they were transferred to Nouméa, New Caledonia,

In the early months of World War II the New Zealand minesweepers had no formal grouping as a flotilla Then Niagra was sunk in June 1940. On 18 July 1940 the Naval Board designated the First Group for coastal minesweeping, and allocated Port minesweepers to the main ports. They were:[7]

On 14 November 1940, a few weeks after the founding of the Royal New Zealand Navy, they were reorganised as the First Minesweeping Flotilla (NZ)

Then on 23 December 1940 the Port minesweepers were separated, and the remaining minesweepers were organised into the 25th Minesweeping Flotilla. This name aligned with the flotilla names used by the Royal Navy. The makeup of this flotilla changed during the course of the war, as new minesweepers were commissioned, others sunk or withdrawn for repairs or refitting, and requirements changed.

Here is a snapshot of the 25th Minesweeping Flotilla on 27 March 1943:

The Port minesweepers were organised into their own flotillas. Eleven new Castle-class minesweepers joined the Port flotillas on completion, 1943–1944.

The RNZN operated two Ton-class minesweepers on anti-infiltration patrols in Malaysian coastal waters during 1966 and 1967. They are the only commissioned RNZN ships never to have visited NZ.

These Admiralty designed coastal minesweepers were built with composite hulls of wood on aluminium frames and a minimum of magnetic material in the hull. They were intended to meet the threat of seabed mines laid in shallow coastal waters. Their shallow draft gave them some protection against pressure and contact mines, and allowed them to navigate in shallow inshore waters. They were 153 feet (47 m) long, displaced 360 tons standard, could manage 15 knots (28 km/h), and had a complement of 32. They were named after British villages which ended with "ton".

Early in 1965 Indonesia was employing a policy of confrontation against Malaysia. New Zealand agreed to assist Malaysia by deploying two Royal Navy minesweepers then in reserve at Singapore. These were commissioned into the RNZN on 10 April 1965 and joined the Royal Navy's 11th Minesweeping Squadron (also Ton class), taking part in anti-infiltration patrols in Malaysian waters.

In their first year they carried out 200 patrols, with 20 incidents involving intruding Indonesians, often taking as prisoners those aboard intercepting small craft. By the time the Indonesian confrontation policy ended in August 1966 Hickleton and Santon had jointly steamed 130,000 miles (210,000 km).