Constrained by draught; 50 metres or more; port side.

Not under command; making way; astern or aground less than 50 metres.

LATERAL MARKS REGION B

This diagram is schematic and in the case of pillar buoys in particular, their features will vary with the individual design of the buoys in use.

Cardinal marks. Cardinal marks are used in conjunction 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 and West) bounded by inter-cardinal bearings, from the point marked.

Tug & tow; less than 50 metres; astern > 200 m in length; port side.

Tug & tow; less than 50 metres; astern < 200 m in length; starboard side.

LATERAL MARKS REGION A

This diagram is schematic and in the case of pillar buoys in particular, their features will vary with the individual design of the buoys in use.

Special marks. 

Definition of Special Marks

Marks used to indicate a special area or feature whose nature may be apparent from reference to a chart or other nautical publication. They are not generally intended to mark channels or obstructions where other marks are more suitable.

Vessel engaged in dredging or underwater operations; 50 metres or more; restricted in her ability to manoeuvre; port side; port side on which may pass.

Tug & tow; less than 50 metres; astern < 200 m in length; port side.

Isolated Danger marks. Isolated Danger marks are erected on, or moored on or above, isolated dangers of limited extent which have navigable water all round them. The extent of the surrounding navigable water is immaterial: such a mark can, for example, indicate either a shoal which is well offshore, or an islet separated by a narrow channel from the coast.

Marking new dangers. Definition of New Dangers 

The term “New Danger” is used to describe newly discovered hazards not yet shown in nautical documents. ‘New Dangers’ include naturally occurring obstructions such as sandbanks or rocks or man-made dangers such as wrecks.

Vessel engaged in dredging or underwater operations; less than 50 metres; restricted in her ability to manoeuvre; stopped and making no way; green lights side may pass.

Restricted in her ability to manoeuvre; 50 metres or more; starboard.

Prior to 1976. There was once more than thirty different buoyage systems in use world-wide, many of these systems having rules in complete conflict with one another.

LIGHT FLASH CHARACTERS.  All lighted aids to navigation, with the exception of those aids equipped with fixed (continuous) lighting, follow an established light flash character pattern. Such characters describe the periodic rhythm of a navigation light, thus enabling it to be identified on charts or while in visual contact.

Tug & tow; 50 metres or more; astern < 200 m in length; port side.

Vessel engaged in dredging or underwater operations; 50 metres or more; restricted in her ability to manoeuvre; ahead; may pass on port side.

Safe Water Marks. Safe Water marks serve to indicate that there is navigable water all round the mark. These include centre line marks and mid-channel marks. Such a mark may also be used to indicate channel entrance, port or estuary approach, or landfall. The light rhythm may also be used to indicate best point of passage under bridges.

Sector Lights

Definition of Sector Lights

A sector light is a fixed aid to navigation that displays a light of different colours and/or rhythms over designated arcs. The colour of the light provides directional information to the mariner.