Hvidbjørnen class Frigate (1962)

The Hvidbjørnen class were four inspektionsskibe (“inspection ships”) later classified by NATO as Frigates despite being 1700 tonnes, built for the Danish Navy in 1961-1963. They were the first post-WW2 large vessels of the Danish Navy to be ordered. Their tasks ranged widely from sovereignty enforcement to maritime rescue and fisheries inspection, and for this they were the first Danish vessels equipped with a helicopter, flown by pilots from the Danish Navy’s Air Service. They were an interesting design really tailored for the immediate needs of the Danish Navy, more for police roles than combat, built at Aarhus Flydedok, Svendborg Værft and Aalborg Værft with General motors diesel for 19 knots for a long range of 6000 nm and only armed with a 76mm gun and depth charges. They were decommissioned in 1990-92.

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Development

Postwar in 1947, the Danish Navy only had two ex-River class Frigates, Holger Dansk and Niels Ebbesens, and the Flower class HDMS Thetis, ex HMS geranium. Its coastal defence could count on two 1943 torpedo boats, four interwar submarines plus four U-class ex-British subs (Springeren class). This was completed by three minelayers and 12 small minesweepers. However, if the Danish Navy’s domestic coastline was split between the North Sea and Baltic its greatest task was to police the waters of Greenland. For this, three ex-Hunt class escort destroyers were purchased, the Ebern Snare class in 1953. They would remain active until 1966 and the Holger Dansk until 1959 and 1963, 1963 for Thetis.

So already a replacement class, better tailored for the role of Greenland patrol, was worked on in 1958. The design was ready in 1959, voted upon with four ships, which main role would be to police these waters with a gun and depth charges, but also from the start designs to operate an helicopter. The Danish Navy envisioned several models but chose eventually the Aerospatiale Alouette III which could land on water. The fundamentals of the new ships, officially designated “inspection vessels” when ordered in 1960 to three different yards was their rugged flush deck hull and robust superstructure. They were design to deal with ice to some extent and had extra heating facilities on a relatively small package and simple to operate powerplant.
NATO later assimilated them to Frigates. They were built between 1961 and 1963, officially to replace the Hunt and River class.

But the main driving force behind the design was the Hans Hedtoft disaster on 30 January 1959 off Greenland, resulting in the design of these four Hvidbjørnen-class inspection ships. The Hans Hedtoft was designed to link Denmark with Greenland, bringing supplies and passengers. She sailed from Copenhagen on her maiden voyage on 7 January 1959 to Julianehaab, Greenland in record time and she called at Nuuk, Sisimiut and Maniitsoq and back to Julianehaab. On 29 January on her return journey with 40 crew, 55 passengers and frozen fish on board plus 3.25 tons of archives on Greenlandic history. She also hosted Danish parliament member Augo Lynge. But she collided with an iceberg about 35 nautical miles (65 km) south of Cape Farewell and a distress call was given at 13:56, answered by USCGC Campbell, and the West German trawler Johannes Krüss. Within an hour she signalled her machinery was flooded and at 15:12, that she was sinking. A final message was sent at 17:41 requested immediate assistance but there was a storm going on, with Aircraft from Newfoundland grounded by the weather. Johannes Krüss received the last message at 18:06 after which communication was lost. Krüss and the USCG cutter Campbell arrived in the area near and gained her position from the initial distress call but between the rough seas and floating ice, dwindling daylight and they were unable to find any survivors. The weather situation even worsened the next day, making any search and rescue operation impossible.
The search was called off on 7 February and a single piece of wreckage was ever recovered, a lifebuoy washed ashore on Iceland on 7 October 1959. This deeply affected Danish authorities and the airfield at Narsarsuaq in Greenland, closed in November 1958, was reopened. The need for dedicated vessels tailored for these conditions was also clear, and none of the ships of the Hunt and River class were adapted for the role.

Design of the class

Vaederren as completed, Navarret coll.

Hull and general design

The Hvidbjørnen class frigates were small but wide vessels, based on a 1.777 tons tonnage, they measured 73,10 meter long (240 ft) for a beam of 11,60 meter (38 ft) and a draught of 5,10 meter (16 ft 7 in) so a ratio of 1/7 in length. The hull was reinforced forward, with a sloped deck and bulwarked, and ended short of the stern with a lower deck for the depth charge launcher and rhibs for inspection, plus cranes. The helideck was partly installed over this lower aft deck. The bulky bridge extended to the beam so to better protect the aft deck, with a single solid mast for its main navigation and air/surface search radar, an there was a hull-mounted sonar as in wartime, they were designed to hunt down Soviet submarines passing through the GIUK gap and deployed in direction of Greenland. Their helicopter was intended for inspection and rescue, not for ASW warfare at first (see later).

Powerplant

Designed for range and not speed, the Hvidbjørnen class frigate were given a simple and reliable powerplant, with four General Motors diesel engines for an output of 6.400 hp, driving through a gearbox, a single shaft and three-bladed propeller aft. The latter was reinforced to brass through ice as well. The hull itself had an icebreaker chin and was reinforced at the bow, chin and along the waterline. This simple powerplant was easy to maintain and repair, with the guarantee of having always three diesels running when one was in that case. Top speed was limited to 19 knots (35 kph), and range at 10 knots was of 6.000 nm (11,112 km), impressive for these small vessels. However, this was barely enough to survey the entire Greenland coastline, covering 27,000 miles (44,000 kilometers). This coastline is longer than the distance around Earth at the equator due to its rugged contour, with numerous fjords, glaciers and islands.

Armament

It was tailored for inspection, so a gun was able to perform warning shots and deal with recalcitrant vessels, but was noted as dual purpose. The depht charge rack or thrower for conways was installed at the poop for ASW work in wartime only. This comprises warning depht charges to deal in peacetime with Soviet submarines in Danish waters.

76mm(3-in)/50 Mk 22 (Maskinkanon M/61 LvSa)

US Pattern gun, shared with USCG cutters, and well known. It went with a shield and wa smanually operated. In AA fire its advantage was the proximity fuze. However there was no fire control radar to guide it to targets so accuracy was limited.
Specs:
1,760 pounds (800 kg), 159.7 inches (4.06 m) and barrel alone 150.3 inches (382 cm) bore (50 calibres).
Elevation +85°, 45–50 rounds per minute with autoloader, MV 2,700 ft/s (820 m/s)
Range 14,600 yd (13,400 m) at 43° elevation and 30,400 ft (9,300 m) AA ceiling.
These frigates also had two stk. 37 mm Salutkanon (saluting guns) usable to send flares as well.

Depth Charges

Type unknown, possibly British by recyling those of the Hunt and River/Flower class vessels.
Some Danish sources points out one Depth charge launcher Mk 1 and two 51 mm Light rocket M/56.

Sensors

These ships had the CWS-1 and NWS-1 radars suite mostly for surveillance.
The Plessey ASW6 luftvarslingsradar (air warning radar) was installed in 1987-88.
The PMS-26 sonar was a British RN hull-mounted, search and attack sonar. The transducer is mounted in a glass-reinforced plastic dome. It was designed to replace the Type 164/174 sonar which were used in combination with a Limbo control set (Type 170). Due to the PMS-26’s shallow tacking capability, Type 170 probably was not replaced in some ships.
In 1987, Hvidbjørnen, Vædderen and in 1988, Ingolf and Fylla so the replacement of their CWS-1, NWS-1 radars by the AWS-6 and Scanter 009 Military radars.

Air Group

One clear advantage of the design was to integrate an helicopter and associated facilities. The Hvidbjørnen class frigate indeed had a hang, starting right aft of the single funnel to house an helicopter, which would otherwise suffer from ice and cold outside. The helideck extended aft almost to the poop. It is not known if there was a trap system to catch the helicopter in rough weather landings. In any cases, the first model adopted was the Sud-Aviation SA316 Alouette III in its naval variants, in which the skids were replaced by inflatable floats. It was used for search and rescue, with a sling and crew of 5. Between 1962 and 1967, a total of 8 Alouette IIIs were delivered to the Royal Danish Navy. They were primarily tasked with SAR and reconnaissance in support of the navy’s Arctic patrol ships. In 1982, they were replaced by British Westland Lynx, of which eight Mk 80 arrived from 1980. They were still used for inspection and SAR, to patrol Greenland and Faroe Islands as well as the Danish mainland.

Career of the Hvidbjørnen class

Hvidbjørnen in Reykjavik, Iceland.
Hvidbjørnen was laid down on 4 june 1961 at Aarhus shipyard, launched on 23 november 1961 and commissioned on 15 september 1962 in a ceremony presided by Viceadmiral S.E. Pontoppidan. She was decommissioned on 30 november 1992. She was the first in her unit, later joined by Vædderen, Ingolf and Fylla, all “inspection ships”.
In 1976, the Danish Navy ordered other four vessels of that type, but modenrized, called the Beskytteren class. Beskytteren was to supplement the four Hvidbjørnen-class inspection ships, as the change in fishing limits from 12 to 200 nautical miles necessitated a much more intensive fisheries inspection. To replace the Beskytteren and Hvidbjørnen classes, four Thetis-class inspection ships were built in the early 1990s. One of these ships was also named Hvidbjørnen, but with hull number F360.

An Alouette III on deck.
Vædderen was laid down on 30. oktober 1961 at Aalborg NyD, launched on 16 april 1962 and commissioned on 19. march 1963.
Hull number was F349 and she joined the same unit with Hvidbjørnen, Ingolf and Fylla. Same remarks as above.
No service logs on line so far.
MoD Poul Hansen assisted her decommissioned ceremony on 31 march 1992.

Ingolf was laid down on 5 december 1961 at Svensborg, launched on 27 july 1962 and commissioned on 27 july 1963.
Ingolf had the hull number F350. She joined her sisters in the same unit and spent her time in patrols along the Greenland coast.
No service logs on line so far.
Her decommissioning ceremony was assited by Kontreadmiral A. Helms on 2 december 1991.

F351 Fylla was laid down at Aalborg on 27 june 1962, launched on 18 december 1962 and commissioned on 10 july 1963.
Fylla received the hull number F351, an inspection ship buut classed as ASW frigate in the NATO book.
No service logs on line so far.
Viceadmiral S.E. Pontoppidan was present for her decommissioning ceremony on 11 july 1991.

Read More/Src

Books

Gardiner, Robert: Conway’s All the World’s Fighting Ships 1947-1995. Conway Maritime Press, 1995.

Links

https://www.navalhistory.dk/Danish/Skibene/Skibsklasser/Hvidbjoernen_klassen(1962).htm
https://da.wikipedia.org/wiki/Hvidbj%C3%B8rnen-klassen
https://www.navypedia.org/ships/denmark/dk_es_hvidbjornen.htm
https://www.retsinformation.dk/eli/lta/1976/597
https://www.facebook.com/100061304031037/posts/velkommen-til-vores-s%C3%B8ndags-opslag-omkring-skibsklasser-i-s%C3%B8v%C3%A6rnet-denne-gang-ha/961403722579753/
https://web.archive.org/web/20100102063046/http://www.vaabenskjolde.dk/
https://www.seaforces.org/marint/Danish-Navy/Frigate/Hvidbjornen-class.htm

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