Admiralty Chart

An Admiralty chart is a nautical chart published by the United Kingdom Hydrographic Office (UKHO), the standard worldwide paper and ENC series used for commercial navigation. Charted depths and drying heights are referenced to chart datum, which the UKHO sets at approximately Lowest Astronomical Tide, so a vessel adds the tidal height of the moment to the charted sounding to get actual depth. Heights of lights, bridges, and overhead clearances reference Mean High Water Springs or Highest Astronomical Tide. The series carries WGS84 positions on modern editions and pairs with the Admiralty Tide Tables for depth planning.