October 27, 2020

Cardinal marks

Cardinal marks are used together with the compass to indicate where the mariner may find the best navigable water. They are placed in one of the four quadrants (North, south, east or west), boundered by inter-cardinal bearings. The mariner is safe if he passes north of a North cardinal mark, […]
October 27, 2020

Isolated danger marks

Purpose. Isolated danger marks are erected on or moored on or above isolated dangers of limited extent which have navigable water all round them. On Admiralty charts the position of the danger is the centre of the symbol or sounding indicating the danger. Top mark. Black double sphere top marks […]
October 27, 2020

Safe water marks

Purpose. Safe water marks are used to indicate that there is navigable water all round the mark. It could be used as a centre line, mid-channel or land fall buoy, or to indicate the best point of passage under a bridge. Colours. Red with white vertical stripes are used for […]
October 27, 2020

Special marks

Purpose. To indicate to the mariner a special area or feature the nature of which is apparent from reference to a chart, sailing directions or notices to mariners. Special marks may be lettered to indicate their purpose. Uses include the following: ODAS (Ocean Data Acquisition System) buoys. Traffic separation schemes […]