Admiralty List of Lights and Fog Signals

Light Characteristics

• The characteristics of a light are also known as its character or characteristic.
• The principal characteristics of a light include the sequence of light and darkness, and in some cases, the colour of the light.

Classes of Lights

• Lights can be divided into three classes: fixed, rhythmic, and alternating.
• Fixed Lights: show continuously and steadily, without interruption.

Rhythmic Lights

• Rhythmic Lights: show a sequence of light and dark, with the whole sequence repeated at regular intervals.
• Period of a Rhythmic Light: the time taken to complete one sequence.
• Phase of a Rhythmic Light: one element of a sequence, such as a flash or an eclipse.

Sources of Light Information

• Admiralty List of Lights and Fog Signals (NP 74 to 84): provides additional information not found on charts.
• Admiralty Sailing Directions (NP 1 to 72): provides only the height and a description of the light structure.