The 24 cm Schnelladekanone Länge 40, abbreviated as 24 cm SK L/40, was a German naval gun developed in the years before World War I that armed a number of the Imperial German Navy's pre-dreadnought battleships and armored cruisers. Later guns removed from these ships were converted to coastal artillery and were used during World War I and World War II. The actual bore diameter was 23.8 cm (9.4 in), but the classification system for artillery rounded up to the next highest centimeter.

HNLMS Jacob van Heemskerck was a unique coastal defence ship of the Royal Netherlands Navy built by the Rijkswerf in Amsterdam. She was among the ships send to patrol the Venezuelan coast during the Second Castro Crisis. After her active career she was rebuilt into a stationary battery ship and recommissioned. During World War II she was captured by the invading German forces and converted in an anti-aircraft battery. After the war the ship was recovered and given back to the Netherlands, to be converted to an accommodation ship.