Ein hoher Leuchtturm steht zwischen Hafengebäuden am Ufer.

Anzeige

Lighthouses, Sectors and Fog Signals: Visible and Audible Navigation Aids

Lighthouses indicate the type of signal by their light color and pattern. A sector light adds positional information: depending on the direction, it shows a different characteristic or color. A fog signal conveys an audible published pattern recorded for that station. The color, characteristic, and range for each station are described in nautical charts and publications.

Light Characteristics and Sectors

A light characteristic is made up of features such as rhythm, color and— for recurring patterns—the duration of a cycle. A fixed light shines steadily, while a flashing light shows a recurring alternation of light and darkness. For its Region B, the Canadian Coast Guard explains that a sector light can show different appearances, particularly colors, across different arcs of the horizon. In this publication, a white sector marks the recommended course or a safe passage. This is an angular area, not a single, exact course line.

Canadian publications give sector bearings as viewed from seaward and list them clockwise; additional visibility information appears in the remarks. At sector boundaries, the perceived color may be uncertain, so official entries describe the sector rather than an arbitrarily precise line. Sector bearings are part of the description of the navigation aid, while other nautical measurements, such as draft, concern a different aspect of safe passage.

Fog Signals in Restricted Visibility

For a fog signal, the type and timing of the sounds help identify the station in the official list. The Canadian Coast Guard explains that entries for audible aids include important details in addition to the signal type, such as the sequence of sound and silence. The signal type combined with the complete timing sequence forms the audible characteristic.

The Trinity House station at Start Point provides a specific example: its published fog signal consists of one blast every 30 seconds; the station’s page gives its range as one nautical mile. A fixed red subsidiary light marks Skerries Bank Shoal there. A port visit is a separate matter from identifying a navigation aid; the terms call, transit and turnaround are covered in this article on cruise port visits.

For accurate interpretation, always consult the publication applicable to the region and station. Sector boundaries, color, rhythm and the sound sequence are described there together with their range or any additional remarks. The article on ship greetings and nautical sound signals explains the meaning of signals from ships.

Photo: Karin Höll