8 533mm (21 inch torpedo tubes) 4 bow, 4 stern, 16-22 torpedoes, fitted for minelaying via torpedo tubes
The Dolfijn class submarines of the Royal Netherlands Navy are a class of four submarines, the Dolfijn, Zeehond, Potvis and Tonijn, Which were built in the late 1950s and the early 1960s. They were the first indigenous submarines built for the Netherlands Navy after World War II.
The Dolfijn class is a special Dutch design and has three separate pressure hulls arranged in a triangle and enclosed in external steel casing. The upper hull for the living/working part of the crew and the lower two hulls were for the engines, batteries and storage rooms. This allows the submarine to dive much deeper than other submarines from the late 1950s, with a test depth of 200 m. The designer was F Gunning.
The order for second group of boats, also known as the Potvis class was postponed in the late 1950s while the possibility of building a nuclear powered submarine was considered and rejected. The order for two boats was re-instated in 1962. These boats had their diesels replaced and electronics updated in 1978-79.
The Zeehond was converted into a trials ship by RDM shipyard in Rotterdam in 1990 and used as a technology demonstrator for a closed cycle diesel air-independent propulsion system until 1994.