Zwaardvisch-class submarine

During the Second World War the Royal Netherlands Navy Submarine Service (OZD) re-evaluated in 1941 the state of its submarine fleet. It concluded that new submarines should be acquired to compensate the loss of and and to replace some older submarines that had become obsolete due their age. As a result in September 1941 a request was made to the British Admiralty to purchase three T- class submarines which were being built as part of a British building program that would be completed by 1942. A year later, in 1944, the Dutch government started negotiations to acquire another T-class submarine. After the Second World War had ended the material of the OZD consisted mostly of old and worn-out submarines. While the RNLN made several plans to modernize the submarine fleet, it took many years till these plans resulted in the construction and commissioning of new submarines. In the meanwhile the RNLN tried to loan some of the surplus submarines that allies such as the United Kingdom (UK) and United States had. In 1947 this led to the UK loaning two T-class submarines to the Netherlands for a duration of five years. The two loaned submarines were during their service in the RNLN also considered part of the Zwaardvisch class. ==Design==

All four submarines of the Zwaardvisch class were built in the United Kingdom at the shipyard of Vickers-Armstrongs in Barrow-in-Furness. The boats had a displacement of 1,320 tons on the surface and 1,580 tons submerged. The boats had a diving depth of . They were considered less advanced than the s. Armament The primary armament of the Zwaardvisch-class submarines consisted of eleven torpedo tubes; eight were located at the bow and three at the stern. Of the eight torpedo tubes at the bow six were installed internally and two externally, while all three at the stern were located externally. Furthermore, the boats could carry a total of 19 torpedoes, with eleven torpedoes being placed inside the torpedo tubes and a further eight for reloads. Besides the two diesel engines, the submarines also had two electric motors that each could produce and three banks of 112-cell batteries with a capacity of 5,350 Ah. The Zwaarvisch-class submarines were also fitted with snorkels. ==Service history==

Second World War The only submarine who saw action during the Second World War was HNLMS Zwaardvisch. While HNLMS Tijgerhaai was also commissioned during the war, it saw no action due to entering service a few months before it ended. While the submarines were not involved in the Indonesian War of Independence and were regularly put in conservation, they did make patrols from time to time. The purpose of the trip was to check how the crew and submarine would perform in cold and icy waters. ==Notes==