Types of navigation aids
Western Australia uses an internationally recognised uniform coding system of navigation marks known as the IALA buoyage system 'A'. A detailed explanation of each navigation mark is provided below, in addition to information on leads, sectored lights and the coming in / going out rule.
Navigation marks are the equivalent of road signs on highways. It is important to be aware of what is meant by the various marks. Take time to study a chart as well as study the buoyage to familiarise yourself with their meaning.
The coming in going out rule
When entering harbours or travelling upstream in a river, leave port hand marks on your port side and starboard hand marks on your starboard side.
When leaving harbours or travelling downstream, leave port hand marks on your starboard side and starboard hand marks on your port side.
One way to remember this is the saying, “there’s some red, port, left in the bottle” when travelling upstream.
Lateral marks are not always placed in pairs where you simply have to pass between them. When you see just one, you will need to bear in mind the upstream-downstream principle.
Types of marks
Marks are used to show well established channels indicating the port (left) and starboard (right) hand side of channels.
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Port mark
Meaning: when travelling upstream, leave port hand marks on your port side. When travelling downstream, leave port hand marks on your starboard side.
Colour: red.
Top mark: can shape.
Light: a red light may be shown. |
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Starboard mark
Meaning: when travelling upstream, leave starboard hand marks on your starboard side. When >travelling downstream, leave starboard hand marks on your port side.
Colour: red
Top mark: cone shape.
Light: a green light may be shown. |
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Safe water mark
Meaning: the water all around is free from obstruction of shallows.
Colour: red with white vertical stripes.
Top mark: single red sphere.
Light: single white long flash every ten seconds, isophase or occulting. |
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Isolated danger mark
Meaning: indicates isolated danger, a submerged object with water all around, don't pass close.
Colour: black with one or more horizontal red bands.
Top mark: black spheres.
Light: white light showing a group of two flashes. |
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Special mark
Meaning: indicates special area - could be spoil or foul ground marks, cable or pipeline marks, including outfall (sewage) pipes or a wreck.
Colour: yellow, at night yellow light.
Top mark: single yellow cross.
Light: yellow, any rhythm may be used other than those used for the white light of cardinal, isolated danger or safe water marks. |
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Cardinal marks
These are used where lateral marks would be inappropriate or confusing. They indicate the compass direction of the safest water, so having a compass on board is very useful. They indicate the safe side to pass a danger or a feature, such as a bend in channel or end of a shoal.
Safe water
You should pass to the east of an East Cardinal mark, to the south of a South Cardinal, to the west of a West Cardinal and to the north of a North Cardinal.
Colours and top marks
The lights, topmarks and colour schemes have a logic to help you memorise them. The cones on top point in the direction of the black segment of the pillar:
- North – both cones top point up, black at the top of the pillar.
- East – the cones point up and down, black at top and bottom.
- South – both cones point down, black at the bottom.
- West – the cones point inwards, black in the middle.
Lights (white)
The lights patterns almost follow the clock face:
- 3 o’clock = East Cardinal = 3 flashes.
- 6 o’clock = South Cardinal = 6 flashes + 1 long.
- 9 o’clock = West Cardinal = 9 flashes.
- 12 o’clock = North Cardinal = continuous flashing.
The long extra flash for south, and the continuous flash for north are to avoid confusion if you lose track with your counting.
Types of cardinal marks
Leads
Leads are a pair of navigation marks, used to indicate a safe passage for vessels entering a shallow or dangerous channel. Leads are separated in distance and elevation, so that when they are lined up vertically, with one behind the other, they provide a bearing. They are usually used to enter a harbour, anchorage or navigate a channel. They are often used for the approaches to anchorages (there are many at Rottnest) instead of lateral marks.
You steer to keep the rear lead directly above the front lead.
Lights
If lit, they may use any colour. The chart will have the details.
Sectored lights
Sectored lights (Woodman Point is an example) are navigation aids that indicate a safe channel through shallow or dangerous waters.
Generally there are three lights of different colours each identifying a sector of an arc. The white sector will generally be the safe water and the red or green sectors areas to avoid. It is particularly important to check the chart for the light’s meaning, purpose and to determine the extent of the safe passage.
To use the lights in the example below the vessel is on the recommended course as long as it keeps within the white sector of the light. If the light colour shifts to red or green an adjustment of course is required to bring it back into the white and back on track.
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