The Walrus class was a class of two submarines that served between 1953 and 1971 in the Royal Netherlands Navy.[3][4] They were former Balao class submarines that were loaned to the Netherlands by the United States under the Mutual Defense Assistance Program (MDAP).[5]
After the Second World War the Royal Netherlands Navy (RNN) was left with several old and obsolete submarines.[6][7] While the RNN made several plans to modernize the submarine fleet, it took many years till these plans resulted in the construction and commissioning of new submarines.[8] In the meanwhile the RNN tried to loan some of the surplus submarines that allies such as the United Kingdom and United States (US) had.[9][10] In the early 1950s this led to the US loaning two submarines to the Netherlands under the Mutual Defense Assistance Program (MDAP), which together would later form the Walrus class.[11][3] Initially the US agreed to loan the two submarines for a duration of five years, however, this was extended twice with five years.[8]
The two submarines of the Walrus class were built in the US by the Manitowoc Shipbuilding Company.[1] They were originally Balao class submarines that had served in the United States Navy (USN).[12] Before both submarines were transferred from the USN to the RNN they had undergone an extensive modernization known as Greater Underwater Propulsion Power Program (GUPPY).[8][9]
Both Walrus class submarines were equipped with four 16 cylinder two-stroke GMC diesel engines that were capable of delivering around 6500 hp when surfaced and 2700 hp when submerged.[13][1][2] This allowed the two submarines to reach a speed of 19 kn when surfaced and 12 kn when submerged.[13] Furthermore, they each had two propellers and two 126 cells batteries.[2] The batteries had a capacity of 10.500 Ah and allowed the Walrus class submarines to operate solely on electric power for 5 hours.[13]
When it came to armaments both submarines were equipped with a total of ten 53.3 cm torpedo tubes of which six were located at the front and four at the rear.[1] In addition, there was enough room to store 24 torpedoes inside the submarines.[13]
In the early 1960s the Walrus class submarines patrolled the waters in Dutch New Guinea and were stationed at Manokwari and Biak.[14][15][16]