Port and starboard marks
- Port hand
- Starboard hand
Heading in the direction of buoyage, keep red port-hand marks on your port side and green starboard-hand marks on your starboard side.
| Port hand | Starboard hand | |
|---|---|---|
| Colour | Red | Green |
| Shape | Can (or pillar or spar) | Cone (or pillar or spar) |
| Topmark, if any | Single red can | Single green cone, point up |
| Light, if any | Red, any rhythm except Fl(2+1) | Green, any rhythm except Fl(2+1) |
Shape matters as much as colour: at dusk or against the sun, a can or a cone is often easier to make out than red or green.
The direction of buoyage
Lateral marks are laid for a vessel approaching a harbour, river or estuary from seaward. Along a coast or in open water, the direction is shown on the chart by a magenta arrow, and generally runs clockwise round large land masses. Leaving harbour, everything reverses: red marks go on your starboard side.
Preferred channel marks
Where a channel divides, a modified lateral mark shows which branch is the main, preferred channel.
- Preferred channel to starboard: red with one broad green band, red can topmark, red Fl(2+1) light. Treat it as a port-hand mark to stay in the main channel.
- Preferred channel to port: green with one broad red band, green cone topmark, green Fl(2+1) light. Treat it as a starboard-hand mark to stay in the main channel.
Region B
In IALA Region B, used in North, Central and South America, Japan, Korea and the Philippines, the colours are reversed: red marks are kept to starboard heading into harbour (“red right returning”). The shapes and cardinal marks are the same in both regions.
The other marks
Cardinal, isolated danger, safe water, special and emergency wreck marks are the same everywhere. See cardinal marks explained for all of them.