HMNZS Otago (F111)

HMNZS Otago (F111) was a Rothesay-class Type 12 frigate, or separately designated, Otago-class frigate acquired from the Royal Navy by the Royal New Zealand Navy (RNZN) before completion. Otago and Taranaki differ from the Royal Navy Rothesays as they were never reconstructed to the Leander standard, with hangar and landing pad for a Wasp a/s helicopter as the main weapon system with a/s torpedoes,depth charges and AS-12 missiles to engage FAC and surfaced submarines. The RNZN frigates were constructed with the long range Type 177 sonar to combine with the only operational MK 20 heavyweight torpedo,(where the RN versions in most cases had an accurate short range Type 174, initially) and provided more comfort for the crew in cafeteria messing and bunk bedding. Otago was launched on 11 December 1958 by Princess Margaret,[1] and was commissioned into the Royal New Zealand Navy on 22 June 1960. The sensors or the Otago were generally updated in line with those of the RN Rothesay,to year 1980 standard, but Otago unlike the RN frigates, was not fitted as a specialised a/s frigates and retained the medium 200km range air and surface warning 277Q, and original 275 and 262 fire control, As ordered the frigate was intended to mount, twin Mk 5 40mm for close in AA but the RNZN decided to rely on Seacat missiles for AA and the Otago and Taranaki carried only a single Mk9 40mm until Seacat was fitted in NZ in 1963-64. During the confrontation with Indonesia in 1964-6, HMNZS Otago, in line with most RN frigates was fitted with a couple of Oerilikons for junk bashing, its sister Taranaki carried older single 40mm initially for the purpose. Later in the decade US Mk 32 tubes were fitted for Mk 44/46 torpedoes in place of the ineffective RN Mk20 torpedoes, in line with the ANZUS alliance, and in the frigates 1974-75 mid life refit, the Limbo mortars were removed as the RNZN anti sub specialists and director of plans viewed Limbo mortars as useless for anything but killing huge numbers of fish in the Hauraki Gulf.

USS Bennington refueling Otago, 1968
New Zealand
Name: HMNZS Otago
Namesake: Otago Province
Builder: John I. Thornycroft & Company, Woolston, Hampshire
Launched: 11 December 1958 [1]
Commissioned: 22 June 1960 [2]
Decommissioned: 7 November 1983
Fate: Sold and broken up, 1987
General characteristics
Class and type: Rothesay-class Type 12 frigate
  • 2,144 tonnes standard
  • 2,577 tonnes full load
Length: 370 ft (113 m)
Beam: 41 ft (12 m)
Draught: 17.4 ft (5 m)
Propulsion: 2-shaft double-reduction geared steam turbines
Speed: 30 knots (56 km/h)
Range: 400 tons oil fuel, 5,200 nautical miles (9,630 km) at 12 knots (22 km/h)
Complement: originally 219, later 240

The ship was named after the province of Otago in New Zealand's South Island, and associated with the city of Dunedin.

Service history

Otago took part in various SEATO (Southeast Asia Treaty Organization) deployments, and took part, with HMAS Supply in support and succeeded by HMNZS Canterbury, in a protest against French nuclear tests at Mururoa Atoll in 1973. She observed the 'Euterpe' test carried out on 28 July 1973,[3] part of the 1971-74 nuclear test series. In the weeks preceding the bomb test, on the account of the operations officer Lt Cdr Gerry Wright and two journalist aboard, HMNZS Otago was constantly monitored and tested by French Navy flying early 1960s model, Neptune 2PV5 maritime patrol aircraft, the predecessor of the Orion used by USN, Japanese, RAN and Argentine Navy (1947-1982) designed for submarine surveillance, the first two Neptune detections, with the Neptune using its USN ANAP-20 USN surface skimming, radar on 6-7-73 at 60nm and 20nm low with passive IFF and radar tracking, and the 'enemy contact report' was canned by HMNZS Otago Captain, Cdr Tyrrell [4] with only fax of close Neptune passes being transmitted to Irirangi and Wellington on account of the secret, sealed envelope instructions by the NZ MOD, CNS and Kirk Government to the Captain and XO [5] that the frigate project authority, but not engage if seriously challenged by French frigates ( similar ambiguous and impractical instructions were given to HMNZS Royalist, by the NZ Govt, MOD and CDS for its Singapore to Townsville passage in 1964). The Neptune's flew various patterns at 140/180 knots, at 1.5nm to 60-80nm range and 70-500 metre height fully testing the Otago's radar, electronic warfare and IFF passive and active capabilities. A couple of Soviet research ships were out of sight 25nm distant and two large USN naval auxiliary and spy ships, USS Corpus Christi Bay and USS Wheeling (T-AGM 8) similar to the USS Liberty attacked in the Mediterranean in 1967 and the Royal Navy had deployed a RFA Tanker and amphibious landing ship, to allow for evacuating the Pitcairns if the French conducted a much larger mega bomb test, which the RNZN anticipated, but didn't happen. The presence of only three small French frigates each with only 3/100mm guns the standard post war French frigate armament, disturbed the Otago's Wardroom, and HMNZS Otago under its Captains command had manoeuvred tactically when approached and shadowed by a medium French Minesweeper with only a Bofors gun.[6] The officers were uninformed of the Captain's limited engagement rules from the CDS to, never fire first,[7] if facing aimed fire, to break contact and return fire, only if necessary, for that end. If at all possible, approval from the CNS before firing was required, as presumably for response to other means of hostile attack, attempted ramming, boarding, light MG fire at frigates or protest craft. The objective was to lead a NZ government, and world protest against nuclear weapon, 'illegal' atmospheric testing, demonstrate ability for 'innocent passage' in international waters, outside the French territorial 12 mile zone and while avoiding confrontation maintain the right to self defence, the RNZN officers fearing a 3 on 1 manoeuvre against them by the French frigates, like the 1939 RN cruisers outflanking Graff Spee. The small French frigate force, probably indicated only a small nuclear trigger test, of 5.4 kiltons (0.66 of the Nagasaki and Hiroshima explosions) was likely, as observed by HMNZS Otago at a range of 21.5 miles at 8am on 21-7-73, and the crew was held in the enclosed citadel for only 20 seconds, and then allowed on the upper deck to observe the nuclear cloud.[8] Cdr Tyrrell who had witnessed the 1957 Christmas Islands hydrogen bomb test saw the explosion as puny in comparison, and well within safe limits for the crew at the distance.

The NZBC journalist, Shaun Brown and David Barber NZPA, from HMNZS Otago, saw it as an 'angry... red fireball' and rising white mushroom cloud.[9] The support of the RAN tanker was essential given the relatively short range of the Type 12 frigates[10] which was just sufficient for a one way trip from Auckland to Mururora, or operate for 36 hours at 25–30 knots (46–56 km/h; 29–35 mph) in all out anti-submarine operations in the Greenland-Iceland UK Gap. The Rothesays were designed for such sweeps and as aircraft carrier escorts with fleet tankers in the group [11] sprinting and searching. The original Whitby T12 were built with extra cruising turbines for fuel economy, but even that variant in the form of HMS Blackpool were spluttering near empty by the time it made the Californian port, covering the 2500 miles from Pearl Harbour to San Diego at 15k.[12] With the need to maintain a 50% fuel reserve at all times, due to need to allow for emergency requirements, weather and barnacle build up on hull, effective range of Otago without refueling is about 3,000 nautical miles (5,600 km; 3,500 mi).[13] Great difficulties were had with all the type 12 variants in sucking the last 20 percent of the fuel from their tanks, and while various solutions were applied, an effective answer began when the RNZN redesign of the Leander in 1968-69 with HMNZS Canterbury, without limbo mortars and enlarged flight deck giving much more below deck internal space. The RN adopting this in the Leander reconstructions from 1971.

In 1960, the Royal Navy had seriously considered the Otago-class design as an alternative to the Rothesay Type 81 general purpose frigates for future development, with a design which would have carried one or two Wessex anti-submarine helicopters.[14] Proposals to fit a hangar and landing pad without the complete reconstruction, as had been done on the Royal Navy Rothesay class which had effectively required the ship to be split in half, were rejected by the Rear Admiral Chief of the Naval Staff on the grounds that nothing should be done that jeopardizes the RNZN case for a new combat ship.[15] The Limbo mortars were finally removed after Exercise RIMPAC '77, after finally being fired on a recruitment cruise off Timaru in mid 1974.[16]

Otago continued as the third combat ship in the three frigate fleet designated by the 1978 Defence Review. In the second half of 1979, the ship had another extensive refit, with its Seacat missile system repaired after breakage, by using stored parts from HMNZS Taranaki's system. In early 1980, the ship deployed to Pearl Harbor and later the West Coast of the United States and Canada for extensive exercises with the United States Navy and Canadian Navy firing hundreds of rounds of 4.5-inch shells, under command of Cmdr Karl Moen, who described Otago as the 'one true fighting ship in the RNZN' with Ltd Cmdr Robert Martin as his second. Martin assumed command during a final six-month refit, leaving the ship on 7 April 1982. Even at the time of the Falklands War, the Captain of Otago and the Minister of Defence, Peter Thompson, declared the ship to still be fully combat capable.[17]

HMNZS Otago became the RNZN training ship in 1983, and paid off into inactive reserve in November 1983. The vessel was sold for scrap in 1987 and broken up at Auckland.


  1. The Times (London), Friday, 12 December 1958, p.10
  2. The Times (London), Thursday, 23 June 1960, p.7
  3. "(1945-1975) French Nuclear Testing at Mururoa". National Museum of the Royal New Zealand Navy. 2015-10-08. Retrieved 2019-10-19.
  4. G.Wright. Muroroa Protest . The Story of the Voyage of HMNZS Otago and Canterbury to Protest French Atmospheric Bomb test at Muroroa Atol 1973. Auckland. 2008,pp 102-105
  5. G. Wright. Otago and Canterbury voyage to Protest atmospheric tests. Lt Cdr Wright (ret)Auckland.2008, p104,
  6. G. Wright. Muroroa Protest. Lt Cdr Wright(ret)(self). Zenith Print NP,NZ (2008)pp 112-14 & 228-31
  7. . Wright. Muroroa, p 231-2
  8. G. Wright.The Muroroa Protest. The Story of the Voyage of HMNZS Otago and Canterbury to Protest against Atmospheric bomb tests at Muroroa. Lt Cdr G. Wright.Auckland (2008)p 157-161
  9. Wright,(2008), p 158-162
  10. D.Grant. The Mighty Totara. The life and times of Norman Kirk. Random House,(2014). Auckland, p.309 & NZ Herald 23 January 1973.
  11. A.Preston. Warships of the World. Janes Publishing,(1980). London, p 152-3 & 164-5.
  12. G.Wright. The Story of HMNZS Blacpool
  13. Interview Captain Ian Bradley (ret) 1983, who approved release, of fuel reserve req, and other info not included in defence articles in NBR and Timaru Herald in 1983.
  14. R. Gardiner. All the Worlds Warships. Pt1. Western Powers. Conway Maritime Press,(1982).London, p164.
  15. Interview Captain Ian Bradley, Auckland 1983
  16. Participants in TBHS school visit to HMNZS Otago 1974 and Officers and Men of HMNZS Otago, 1974 and background interviews, with Capt Ian Bradley 82-84 for TH articles and NBR 83-7
  17. NZPD Debates 1982.

Further reading

  • Wright, Gerry (2015). Operation Pilaster: The story of the voyages by the frigates HMNZ ships Otago and Canterbury, supported by the Australian naval tanker, HMAS Supply, to protest against the French atmospheric nuclear tests at Mururoa Atoll in 1973. Auckland: Gerry Wright. ISBN 9780473327712.
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