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Since the mid-16th century, the Royal Danish Navy has been responsible for fishery inspection in the North Atlantic (see sidebar next page). The economic growth of recent years has necessitated the development of a new class of ships to enable the Navy’s Fishery Protection Squadron to carry out their inspection of the numerous trawlers that ply Danish waters.
To that end, in 1987, after lengthy staffing and political debates, the Thetis class of ships was authorized. The criteria they meet are: strong enough to operate off the east coast of Greenland, sometimes in 80 centimeters (31.2 inches) of solid ice; large enough to carry a Lynx helicopter, a 24-day supply of fuel, and a four-month supply of rations and water; capable of speeds better than 20 knots; and spacious enough to accommodate a crew of 60.
The four ships in this class were built by Svendborg Shipyard. The first ship, HDMS Thetis, was delivered to the Royal Danish Navy in August 1990 for weapons installation. Each ship has a displacement of 3,500 tons, a length of 112 meters (368 feet), and a maximum speed of 21 knots (using diesel propulsion). The armament
Hearty Danish sailors surely earn themselves a glass of Aquavit after four months of navigating the Arctic Ocean, where they dodge icebergs up to ten feet thick and maneuver their Thetis-class frigates in the frequent storms.
consists of one OTO Melara 76-mm. gun.
The Thetis made a trial trip in December 1990 to the Faroe Islands and Greenland during which all tests were completed satisfactorily. Nevertheless, seismographic equipment was installed before the ship was commissioned for oil prospecting off Greenland. The stem and quarterdeck were modified to allow operation and storage of a three-kilometer (3.18 miles)-long seismic cable.
The Thetis traveled as far as 79° north latitude in the fall of 1991. As part of the preparation for that seismic cruise, she was equipped with a receiver for the sidelooking radar operated by the Gulfstream III aircraft in order to detect ice. Normally, the ships of the Fishery Protection Squadron avoid the ice, which might easily crush a ship, but when towing a floating seismic cable at a constant speed and a steady course, the ice cannot be avoided. The hull shape was well suited for this purpose and superbly protected the single propeller and rudder.
The HDMS Triton, the second Thetis- class vessel to be finished, was commissioned in December 1991, and sailed on her shakedown cruise in January 1992. Her few short trips around the Danish islands, however, did not reveal the problems she would encounter in rough weather in the North Atlantic. The protective cover plates over the fairleads to the closed forecastle were destroyed by the seas and no spares were on board. Consequently, the forecastle quickly filled with water. The ship had to be turned down sea to be repaired with canvas and wire lashings. Heavier plate was installed at a shipyard in Torshavn, the largest city in the Faeroes.
The movements of the ship at sea were quite heavy, but they were compensated for by trimming after a trial-and-error process. Rolling is compensated for by folding fin stabilizers that perform well at speeds over eight knots. At slower speeds an antiroll tank system takes over (which is also used for operations in ice where the fins could be damaged). The tank system has a mode with manual heeling operations that can be used if the ship is trapped in the ice. The Triton maneuvers extremely well. The flap- rudder and bow-thruster make berthing in small harbors in the operational area very easy.
The job of keeping a proper lookout in the cold weather of North Atlantic winters is problematic. The bridge is fully enclosed, with panoramic windows in front that are heated by hot wires or air blowers. The salt from the seaspray quickly forms an opaque white layer on the heated windows, and visibility is lost. The window wipers and antifreeze fluids can operate only a few minutes before the tubes jam and the wipers become coated with ice. A simple working solution has still not been found.
The high-tech equipment worked quite efficiently. For instance, the fire-control system in search-and-rescue operations was excellent. The shoreline can be checked for wreckage at night by an infrared camera, and the C3 (command, control, and communications) system orchestrated the search. All sensors are connected via a data bus, and the results can be displayed in the combined bridge/operations room. At one time 10 trawlers were directed in a combined 24-hour search for a missing fishing boat.
The ships control and supervisory system (SCSS) makes remote control of all machinery, ventilation, and damage-control systems possible from the bridge, thereby eliminating the need for guard duty in the engine rooms. At the end of the cruise, the crew requested more detailed types of displays and controls. Similar control systems introduced in the merchant navy have resulted in reducing their crews to
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Proceedings / March 1993
The element of surprise is used effectively by the Royal Danish Navy’s Fishery Inspection Squadron. A Lynx helicopter lowers an inspector, unannounced, onto a trawler, here fishing off the coast of Greenland, to check on its adherence to regulations and quotas.
patrols were replaced by area inspection. A system of licences and fishing quotas was established, and, it could be argued, the concept of mare clausum was almost revived.
ing program in the 1960s produced five ships of approximately 1,800 tons each, plus five smaller cutters. In 1977, the 200-nautical mile fishery zone was introduced. This enlargement of the area to be surveilled meant that border
The Fishery Protection Squadron (now Squadron No. 1) of the Royal Danish Navy dates back to 1587, when eight frigates were equipped to patrol and enforce the Danish king’s rights to the eastern part of the North Atlantic.
These northern seas were considered the king’s possessions—a mare clausum—and the captains of the Fishery Protection Squadron were instructed to forbid and prevent other nations from trading and fishing there, by use of force, if necessary. Even transiting the seas was considered illegal.
At its zenith the Danish kingdom included Norway, Iceland, the Faeroes, and Greenland. Over the centuries the legal position of the seas surrounding these countries has changed, and the principle of freedom of the seas has eventually been applied. Because it was impossible to monopolize the seas, it became the Danish Navy’s job, rather, to protect the country’s trade. To those earlier tasks of protection and surveillance have been added search and rescue, meteorological and ice- formation observations, surveying (maps and charts), towing, medical assistance, and transportation.
Denmark and Norway separated in 1814. Denmark established a three-nautical mile territorial limit in 1882 that applied to Iceland, Greenland, and the Faroe Islands. Most of the activities of the Fishery Protection Squadron then became closer to the coast and consisted of surveillance and charting. The fishery gradually expanded farther out, but with Iceland’s declared independence in 1944, a large area was eliminated from the operational waters of the Royal Danish Navy.
After World War II the Fishery Protection Squadron had to be completely rebuilt. Materiel was procured from other countries—at first, surplus British ships—and a new build
a bare minimum. A large freighter, for example, might operate with a crew of only eight or nine persons.
A lot of consideration has been given to the size of the crew in the Thetis-class Patrol frigates. For routine cruising and fishery inspection, 60 men are actually too many, but during extensive helicopter operations and assistance to the trawlers, especially in rough weather, the size of ihe crew is requisite. Having been outfitted with semi-automatic weapons, sen- tors, and modern firefighting equipment, toe Triton is capable of actual fighting and damage control, at least for a short Period of time, with the present crew size.
Operations with the sonar equipment Were challenging and posed a number of new problems, such as how to select a good strategy for a search, how to se- toct towing depth and speed, and how to avoid mutual interference.
Helicopter operations with the Lynx Were performed extensively in order to establish the maximum safe envelope of relative wind speed and direction under takeoffs and landings. It was possible to extend the boundaries of these SHOL (Ship Helicopter Operational Limitations)
Proceedings / March 1993 beyond the range of previous Danish naval vessels. The correct positioning of anemometers to give accurate wind data for gunnery, meteorological observations, and helicopter operations was a laborious process because the measurements were subject to interference from the superstructure, funnel exhaust, and the masts. A series of wind-tunnel tests had to be performed before a satisfactory solution was achieved. We established that the existing deck-handling equipment needed refining. Guide rails are now being installed that will make deck operations possible even in a relative wind speed of 50 knots.
Whenever possible, exercises are arranged with other NATO units that pass or operate close by. This gives a welcome break from ship’s routine and a chance to learn even simple procedural tasks like establishing communication or joining. A closer look at the Allies’ capabilities and technologies in more difficult exercises is of great value.
The Triton's last task during her maiden voyage was to cross the Atlantic to take part in the ComDef 92 naval exhibition in Norfolk, Virginia, in March 1992. Later that month she celebrated Transfer Day in the U.S. Virgin Islands to commemorate the 75th anniversary of the U.S. purchase of the Danish West Indies in 1917. The Triton called at Fred- eriksted, St. Croix, and Charlotte Amalie, St. Thomas, demonstrating the ship’s ability to operate in subtropical waters.
The Royal Danish Navy’s Thetis-class oceangoing patrol frigates will operate in the North Atlantic: one on the west coast and one on the east coast of Greenland, plus one in Faroe Islands waters. (The fourth frigate rotates in and out whenever one of the other three needs routine maintenance or repairs.) They will perform a number of peacetime, nonmilitary tasks, which means that they are on station year-round. These patrol frigates have good endurance and a lot of flexibility and growth potential. They will form the backbone of the Royal Danish Navy in the years to come.
Commander Hornhaver graduated from the Royal Danish Naval Academy in 1967. He has served in the Fast Patrol Boat Squadron, 1968-73, Naval Materiel Command, 1978-85, and as Commanding Officer of the HDMS Ingolf (1987-88), Hvidbjomen (1989-90), and Triton (1991-).
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