Are we heading upstream or downstream?

Boaters are often uncertain about which side of a channel marker they should pass. This is because they are not sure whether they are travelling upstream or downstream

On the road drivers cannot deviate from the structured roadway system. How a vehicle is to be driven safely is determined using marked roadways, stop signs, traffic lights and speed limits. On the water you are confronted with an expansive waterway where there are no lines to guide your passage. In addition, you’re dealing with wind, tidal changes, heightened sea states and unfamiliar marks and beacons.

It is important for Skippers to know the upstream and downstream rule so that they can identify which side of a particular channel marker to pass safely and not run aground.

Green to Green when travelling upstream. Green to Red when seas ahead.


  • A vessel travelling downstream on the river is navigating from inland towards the sea.
  • A vessel travelling upstream on a river is navigating from sea towards the inland or mountains.
  • Always maintain a good lookout, keeping to the starboard side of the channel.
  • Do not cut corners on a river bend. This is due to current flow which causes sand and silt to be deposited on the uppercurve of the river causing shallow water. The lowercurve of a bend has the deepest water.
  • Be cautious when approaching a blind right-hand bend. Another vessel maybe navigating on the wrong side. Sound one long blast to let other vessels know of your presence.
  • Port and starboard channel markers indicate where to safely navigate within the channel.
  • A port marker is coloured red and the starboard marker is coloured green.
  • When travelling upstream keep a green starboard channel marker on your starboard-side.
  • When travelling downstream keep  the green starboard channel marker on your port-side  and, a red port channel marker on your starboard side.


Driving your vessel on a river you see a channel marker. However, you are unsure which direction you are travelling upstream (in from sea) or downstream (out to sea).

Determine whether you’re travelling upstream or downstream.

  • Ask a fellow boater or locals  which direction is towards the sea?
  • Identify the buoyage direction for the area on your chart.
Look for this symbol on a chart or boating map.
  • Establish high and low tide times from a tide table of the area. This information will help you to identify which direction is up or downstream by determining the direction the current is flowing. Example: If a high tide is earlier and the tidal height is falling, then the current is travelling (downstream) out to sea. If a high is later and the tidal height is rising, then the current is then travelling (upstream) in from sea.
  • Know the characteristics of the lateral channel marks.

You will learn about this boating rule when attending a one day boat licence course. The upstream – downstream rule is simply explained and demonstrated to on the water – where it counts the most!

Starboard channel mark

Port and Starboard Channel Markers

Port and Starboard channel markers are internationally recognised  sea marks (buoys) used in maritime pilotage to indicate the edge of a channel.

Each mark indicates the edge of the safe water in a  channel.

Port Channel Marks

Port Channel Mark
Referred to as lateral marks, Port marks are red and have a can shaped topmark.

Colour: Red Buoy
Shape:  Cylindrical (can), pillar or spar Top Mark:  Single red can.
Numbering: Even numbers

LIGHT Colour: Red Rhythm:  If lit it can display: Q.R – continuous quick flashing red light. FL.R .3s- red single flash.(flashes for 1 sec, darkness 2 secs = 3 secs rhythm sequence) L.FL.R – red long flash FL.(2).R – red group flash.

Starboard channel mark
Starboard marks are green and have a cone shaped topmark.

Colour: Green Buoy
Shape:  Conical, pillar or spar. Top Mark:
Single green cone pointing upwards.
Numbering: Odd numbers

LIGHT Colour: Green Rhythm:  If lit can display:Q.G – continuous quick flashing green light.
FL.G.3s green single flash. (flashes for 1 sec, darkness 2 secs = 3 secs rhythm sequence)
L.FL.G green long flash (flash 2 secs or longer)
FL.(2).G green group flash

IALA Buoyage System

The marks are positioned on Australian waterways according to a conventional direction of buoyage which is stipulated in the International IALA Buoyage System A.

IALA Buoyage System A
IALA Buoyage System A

What it means

When operating on a river, the direction of buoyage will be towards the river’s source, while in contrast when operating on a harbour, the direction of buoyage is into the harbour from the sea. Buoyage direction is labelled on area charts and boating maps. Hence, it is important to understand the direction of buoyage as it determines the side which you should pass the channel mark to stay in deep water within the channel.

Consequently, when you understand the direction of buoyage, the lateral marks and correct side to pass them all make sense.

So, if you are heading in the direction of buoyage, into a harbour, coming in from sea, travelling in an upstream direction towards land, the starboard marks will be on your starboard (right) side. If you are heading against the direction of buoyage, in a downstream direction, going out towards sea the port lateral marks will be on your starboard (right) side.

Lastly, remember:
A vessel heading upstream into a harbour, from from sea, wanting to keep in the main channel must: Keep port marks to its port (left) side and pass starboard marks to its starboard (right) side. A vessel heading downstream, towards sea wanting to keep in the main channel must: Pass port marks to its starboard (right) side port and keep starboard marks to its port (left) side.

Ulmarra Vehicular Ferry

Vehicular Ferries

Ulmarra Vehicular Ferry
Ulmarra vehicular ferry, Clarence River, NSW.

Vehicular ferries are significantly restricted in their ability to manoeuvre. Give way to them.

Vehicular ferries drag themselves across channels using wire cables. These cables are below the water and the danger of striking a ferry wire may not be seen. As the the ferry is being hauled across the river it causes the front cable to become taut and rise up towards the surface.  The best option is to wait until ferry is on the bank and loading/unloading when the cables are slack.

What to do when approaching a vehicle ferry

  • Slow down to 4 knots within 100 metres and sound a signal if you crossing and the ferry has not departed.
  • Do not pass ahead of vehicular ferry whilst it is travelling across the river. Stop, give way and wait until it has  reached the ramp.
  • A vehicular ferry underway will display a orange all-round flashing light by day and night.

At night the vehicular ferries display an all-round red light at both ends with an all-round green light over the red light to indicate the direction of travel.

Navigation Lights Vehicular Ferry

Keep to the starboard side or the river,  slow down and keep well clear.