The Battenberg Course Indicator was designed to aid speed and distance calculations, in particular tracking the position of a ship relative to others, and was of particular use when moving in large convoys.

The main body of the instrument, which is made of a light alloy, has a degree scale marked on its outer edge. The guide's bar, with the large pointer, is set to the compass course of the guide ship. The bar pivoted at the centre of the small circle has a scale for speed and the other two bars have scales for distance. The instrument is contained in a painted wooden box, which also holds a metal guide bar for the instrument.

Station, speed and distance indicators were first developed following the introduction of fast steam ships, when it became more important to be able to calculate the course and speed of other vessels within sight. The Battenberg course indicator was invented in 1892 by Prince Louis of Battenburg (1854-1921), who later became First Sea Lord.