Buoys, beacons and marks

Isolated danger marks

Isolated danger marks are placed on, or moored above, an isolated danger of minimal area below the water around the mark. The water around the mark is safe to navigate. The colours are red and black horizontal stripes and the mark is, when practicable, also fitted with a black top mark of two vertically aligned spheres.

Isolated danger marks

Isolated danger marks are not always positioned centrally over a danger so to be safe do not pass too close to the mark.

If the mark is lit, the light will be white showing a group of two flashes. Two white flashes of light is the equivalent of two spheres.

Safe water marks

Safe water marks show that there is navigable water all around the mark and can be used as a centre line, mid-channel or landfall buoy.

The shape of the buoy is spherical, pillar or spar (a round pole shape) and is coloured with red and white vertical strips. The top mark that's fitted when practicable to pillar and spar buoys, is spherical and red.

If lit, it shows an isophase occulting or single long flashing white light. An isophase is a special class of light which alternates eclipses and flashes of exactly equal duration. The buoy shape is optional but should not be in conflict with the buoy used for a lateral or special mark.

safe water marks

Operators of vessels are cautioned that large commercial vessels may pass close by these marks.

Channel markers

Channel markers indicate the port and starboard limits of a narrow channel that has been dredged in a river or the approaches to a harbour to allow safe passage of large vessels.

The waters outside the channel may be shallow or conceal rocks and other hazards to navigation. Navigating outside the marked channel could result in a vessel running aground and sustaining serious damage.

Entrances to harbours or breakwaters may utilise different distinguishing characteristics, for example, white flashing lights. Please seek advice from the local marine authority.

Types of markers

Two types of marker are used to indicate the port and starboard limits and these may be either fixed or floating.

channel marks

The positioning of the two types of marker is determined by the general direction taken by a vessel when entering a harbour or proceeding upstream.

Under this convention a vessel entering, for example, the Port Adelaide River would keep the port (red) markers on her port side and the starboard (green) markers on her starboard side.

When leaving the harbour or proceeding downstream the situation is reversed, meaning that the port markers should now be passed on the vessel's starboard side and vice-versa.

Day marks

Day marks are shown by day in all weathers on boats to denote certain situations that may limit the vessel's ability to respond to other vessels, including when visibility is restricted, and must be recognised by vessel operators.

Vessel is restricted in its ability to manoeuvre

daymark restricted manoeuvring

Black ball, black diamond and black ball.
For example boats engaged in cable laying, replenishment at sea, underwater operation, servicing navigation marks or towing, where towing affects the manoeuvrability.

When at anchor, vessel also shows anchor shape. This signal does not indicate distress or a need for help.

Vessel at anchor

vessel at anchor

One black ball.
Located forward, where best seen.
Not required for boats of less than seven metres. Used when at anchor not in a channel or channel approach, or a usual anchorage.

Vessel under power with sails set

daymark under power with sails

One black cone, point down.
Located forward, where best seen.

Power-driven vessel towing another vessel

daymark powered vessel towing
towing measurement

One black diamond on each vessel where best seen if length of tow exceeds 200 metres.

Vessel aground

daymark vessel aground

Three black balls.
Located where best seen, but not required for boats of less than 12 metres. This signal does not indicate distress or a need for help.

Vessel not under command

daymark vessel not under command

Two black balls.
Located where best seen. Not required for boats of less than 12 metres. Indicates an inability to manoeuvre, but does not signal distress or a need for help.

Boats fishing

daymark fishing vessels

Two black cones.
Indicates trawls, nets or other gear - underway or at anchor, point inwards. If fishing vessel is less than 20 metres, she may instead show a basket.

Vessel constrained by her draught

daymark vessel constrained by draught

One cylinder.
Located where best seen indicates a power-driven vessel restricted to a narrow channel by her draught and therefore unable to deviate from course.

Port closed or channel blocked signal

The port closed or channel blocked signal is used to indicate a thoroughfare to navigation that's blocked. The signal may come from a shore station or from any vessel that's blocking the channel.

Port closed or channel blocked signal

The marks are made up of three black shapes in a vertical line. The highest and lowest of these shapes shall be a ball and the middle on a cone with apex upwards.

Night mark - Port closed or channel blocked signal

Three all round lights in a line where they can be best seen. The highest and lowest of these lights shall be red and middle light shall be green.

Channel blocked signals are increasingly likely to be seen in the River Murray and lakes as the ongoing effects of low water levels cause restrictions to some areas of water.

Cardinal marks

A cardinal mark indicates where the safest water may be found and is best used together with a compass. It shows where the mariner can safe pass safely and may:

  • indicate the deepest water in an area
  • show the safest side to pass a danger
  • draw attention to a feature in a channel such as a bend, junction or an end of a shoal.

cardinal marks

Think of a clock face when remembering the lights on cardinal marks. Three flashes for east, six flashes for south and nine flashes for west.

By day the colour scheme can be remembered by noting that the black segment is positioned where the cones point.

  • North - the top mark points up and black segment is at the top
  • East - the top marks point outward and there are black segments top and bottom
  • South - the top mark points downward and the black segment is at the bottom
  • West - the top marks point inward and the black segment is in the middle.

Top marks

Black double cones, clearly separated.

Colours - black and yellow horizontal bands with the position of the black band or bands relative to the respective cardinal points.

top mark north North Top mark points up, black band above yellow band.
top mark east East Top mark points outward, black bands above and below yellow band
top mark south South Top mark points down, black band below yellow band
top mark west West Top mark points inward, black band between yellow bands

Special marks

Special marks are used to point out a special area or feature on the water. The nature of the area or feature may be found by consulting a chart or sailing directions of the area.

Special marks are always yellow and the top mark, if fitted, is a single yellow X. If a light is fitted it will be yellow and may have any rhythm not used for white lights, for example diagram: FlY, Fl (4) Y.special marks

In South Australian waters special marks are commonly used to indicate no boating zones or speed restricted areas.

Lateral marks

Lateral marks are usually positioned to define well-established channels and indicate port and starboard sides of the navigation route into a port.navigating lateral marks

Port mark is coloured red and the basic shape is a can.lateral marks port

Starboard mark is coloured green and the basic shape is conical.lateral mark starboard

By night a port buoy shows a red light and a starboard buoy shows a green light.

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Page last updated 18 August 2020

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