2 min read · Updated 25 June 2026
Buoyage is the system of buoys and beacons that guides vessels safely — showing where the safe water is and warning of dangers. Reading it correctly is essential seamanship, and the good news is that the marks follow a standard system of shapes, colours, topmarks and lights. The two most important families are lateral marks and cardinal marks.
Lateral marks — the sides of a channel
Lateral marks show the sides of a channel — which side to leave them as you pass through. In IALA Region A (which covers most of the world, including Australia):
- Red, can-shaped marks are port-hand marks.
- Green, cone-shaped marks are starboard-hand marks.
When entering a harbour or proceeding in the "buoyage direction" (generally in from seaward), you keep the red port-hand marks to port (your left) and the green starboard-hand marks to starboard (your right). One important warning: the Americas use Region B, where the colours are effectively reversed ("red right returning") — so always know which region you are in.
Cardinal marks — where the safe water is
Cardinal marks point to where the safe water lies relative to a danger, using the compass:
- A North cardinal means the safe water is to the north — pass to the north of it.
- An East, South or West cardinal means pass to the east, south or west respectively.
They are yellow and black with distinctive double-cone topmarks, and the arrangement of the colour bands and the topmark cones encodes which compass direction they refer to. A handy memory aid: the topmark cones "point" towards the black band. When in doubt, the exact pattern for each is shown on the chart and in almanacs.
Other marks
A few more marks complete the system:
- Isolated danger marks — placed on or near a small danger with navigable water all around; black with red bands and two black balls as a topmark.
- Safe water marks — indicating navigable water all around (such as a channel entrance); red and white vertical stripes.
- Special marks — yellow, marking areas or features that are not primarily navigational, such as spoil grounds, cables or racing marks.
Reading it together
Buoyage works hand in hand with the chart: the chart shows where the marks are and what they mean, and the marks confirm your position and the safe water on the ground. Together with the rules of the road, they are how vessels move safely through busy and hazardous waters. For the rest of the vocabulary, see the sailing terms glossary.
Frequently asked questions
- What is buoyage?
- Buoyage is the system of buoys and beacons — collectively called navigation marks — that guides vessels through safe water and warns them of dangers. The marks come in standard types with agreed shapes, colours, topmarks and light patterns, so that a sailor can read them at a glance. The main types are lateral marks, cardinal marks, and a few special-purpose marks.
- What are lateral marks?
- Lateral marks show the sides of a channel — which side to leave them as you pass. In most of the world (IALA Region A, which includes Australia), red can-shaped marks are port-hand marks and green cone-shaped marks are starboard-hand marks. When entering a harbour or proceeding in the buoyage direction, you keep the red port-hand marks to port and the green starboard-hand marks to starboard.
- What are cardinal marks?
- Cardinal marks indicate where the safe water lies relative to a danger, using the points of the compass. A North cardinal means the safe water is to the north of the mark (pass to the north of it), an East cardinal means pass to the east, and so on. They are yellow and black with distinctive double-cone topmarks, and their colour bands and topmarks encode the compass direction.
- Does Australia use red-right-returning?
- No — that is the Region B rule used in the Americas. Australia, like most of the world, uses IALA Region A, where you keep red port-hand marks to port when entering. It is worth being clear on which region you are in, because the lateral mark colours are effectively reversed between Region A and Region B.
- What other navigation marks are there?
- Besides lateral and cardinal marks, there are isolated danger marks (placed on or near a small danger with safe water all around, black and red with two black balls as a topmark), safe water marks (indicating navigable water all around, red and white stripes), and special marks (yellow, marking areas or features like spoil grounds or racing marks that are not primarily navigational).