Maritime & BoatingExamRoo practice revision sheet
Navigation Marks (IALA System A) Decoder
Colour, topmark and light guide to lateral, cardinal and other marks, as described in the NSW Boating Handbook
Based on: Transport for NSW (NSW Boating Handbook)•3 min read (Printable)•Sources checked 14 October 2026
Lateral Marks (Port and Starboard)
Lateral marks define the sides of a channel. When port and starboard marks are in a pair, travel between them.
| Mark | Colour and shape | Light (if lit) | Single mark, travelling upstream | Single mark, travelling downstream |
|---|---|---|---|---|
| Port mark | Red, can-shaped topmark or buoy | Flashing red | Keep it on your port (left) side | Keep it on your starboard (right) side |
| Starboard mark | Green, cone (triangle) topmark or buoy | Flashing green | Keep it on your starboard (right) side | Keep it on your port (left) side |
Note: Upstream means travelling away from the sea. Memory aid from the handbook: green to green when going upstream, green to red when seas are ahead.
Cardinal Marks (Safe Side of a Hazard)
A cardinal mark shows the safe water is on its named side. For example, pass a north cardinal mark on its northern side.
| Mark | Topmark cones | Black and yellow bands | White light (if lit) |
|---|---|---|---|
| North cardinal | Both point up | Black above yellow | Continuous quick or very quick flashing |
| East cardinal | Point away from each other (looks like an egg) | Black top and bottom, yellow in the centre | Groups of 3 quick or very quick flashes |
| South cardinal | Both point down | Yellow above black | Groups of 6 quick or very quick flashes, then a long flash |
| West cardinal | Point towards each other (looks like a wine glass) | Yellow top and bottom, black in the centre | Groups of 9 quick or very quick flashes |
Note: Clock-face memory aid for the lights: north continuous, east 3 flashes, south 6 flashes plus 1 long flash, west 9 flashes.
Other Marks
| Mark | Appearance | Light (if lit) | Meaning |
|---|---|---|---|
| Isolated danger | Black with a red band, 2 round black topmarks | White, groups of 2 flashes | A specific danger (such as a wreck) surrounded by generally safe water. Pass on any side, but not too close. |
| Safe water | Red and white vertical stripes, may have a red round topmark | White flashing | Navigable water all around. If it marks a channel centre line or turning point, keep it on your port side. |
| Special mark | Yellow, may have a yellow X topmark | Yellow, any pattern | Special features or areas, such as tide poles, spoil grounds or underwater pipes. |