Moray^[a] was the name of a proposed new class of submarines developed by the Rotterdamsche Droogdok Maatschappij (RDM).^[5][6] While a Moray class submarine was never actually built, the detailed design of the submarine class was fully completed.^[7]

A Moray class submarine could be built in several sizes depending on the type of submarine that was needed.^[8] For smaller submarines that would patrol off the coast there was a design that ranged from 1,100 ton to 1,400 tons displacement, whereas oceangoing submarines ranged from 1,800 to potentially 2,000 tons displacement.^[9][10] Besides customization RDM also offered three standard types of Moray class submarines which were called the 1100, 1400 and 1800.^[11] The number stood for roughly the amount of tonnage of the submarine. The three types had a length of 55.7 meters (182 ft 9 in) (1100), 64 m (210 ft 0 in) (1400) and 75.9 m (249 ft 0 in) (1800), while the beam was 6.4 m (21 ft 0 in) and the draft 5.5 m (18 ft 1 in).^{[citation needed]} The smallest submarine, the 1100, had space for a crew of 26.^[12] The 1800 had space for a crew of 41.^[1]

While the Moray class was derived from the Walrus class, it had several differences with that class.^[13][6] The main difference was that the size of a Moray class submarine was significantly smaller than a submarine of the Walrus class, which displaced around 2,800 tons.^[14][15] Another difference was that the hull of the Moray class was, unlike both the Zwaardvis and Walrus class submarines, not in the shape of a tear drop.^[1] The more straight-lined hull of the Moray class made it possible to extend or shorten the submarine.^[2] It also allowed the insertion of a hull section that included a air-independent propulsion (AIP) system.^[2] The insertion of the AIP module would increase the tonnage of the submarine by 200 tons.^[4] A submarine of the Moray class could also dive less deep than a Walrus-class submarine.^[16] The Moray class submarines had a estimated diving depth of more than 300 m (980 ft).^[1][11] The Moray 1800 had the same amount of battery cells as the Walrus class submarines and a endurance of 65 days.^[4] When it comes to armaments the Moray class was equipped with six 533 mm (21 in) torpedo tubes that could launch a variety of weapons, such as Mark 48 torpedoes and Harpoon missiles.^[3]

The price of a Moray class submarine was estimated to cost around 220 million Dutch guilders in 1989.^[1]

In June 2018 a concept of an fully electric submarine based on the Moray 1800 design was presented at the submarine symposium UDT in Glasgow.^[17] In the revealed concept the diesel engines and all related equipment were removed from the Moray 1800 design together with the lead-acid batteries; these components were instead replaced with lithium batteries.^[18][17] The lithium batteries allowed the 1,800-ton submarine to stay at sea for three weeks before needing to return to recharge its batteries.^[18] In addition, there were several advantages and disadvantages to using only lithium batteries to power a submarine.^[17]

• Viking-class submarine

• Darman, Peter, ed. (2004). Twenty-first Century Submarines and Warships. Military Handbooks. Rochester: Grange Books. ISBN 1-84013-678-2.
• Schoonoord, D.C.L. (2012). Pugno pro patria: de Koninklijke Marine tijdens de Koude Oorlog (in Dutch). Franeker: Van Wijnen. ISBN 978-90-5194-455-6.
• van den Pol, E. (1989). "Aspects of submarines - Part I: Some notes on development". Schip en Werf. Vol. 56, no. 10. Rotterdam: Wyt & Zonen. pp. 352–358. ISSN 0036-6099.

• Scale model of a Moray-class submarine at the Rotterdam City Archive (Dutch: Stadsarchief Rotterdam).