Boating Navigational Marks

Navigational Marks and What They Mean

Last updated on December 21st, 2018 at 04:02 pm

Before heading into the water, you, like any other boater have the responsibility to familiarise yourself with the navigational marks. Understanding navigational marks are essential to your safety on the water. They function similarly to road signs or traffic lights — but in the water. Keep an eye out for beacons, buoys and, lights to keep everything smooth sailing.


About 30 buoyage systems were used all over the world before the 1970s. It caused a lot of confusion and, even led to fatal accidents in the Dover Straits. This prompted a worldwide effort to have a unified marine buoyage system to prevent future mishaps. The result was the creation of the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) in 1971.

The biggest breakthrough happened in 1980 when the world began using all but two buoyage systems. These are known as Maritime Buoyage IALA A and, IALA B. While this is certainly an improvement in unifying the buoyage systems, there are minor differences that boaters should note. The goal of developing just one system used internationally is still in the works.

IALA – A – The whole of Africa uses this system as well as Europe, some countries in Asia (ex. India, China etc.) and the whole of Australia.

IALA – B – This is used in North, Central and, South America and, Asian countries like Japan, Korea and, the Philippines.

Navigational Marks

Lateral Marks

Lateral marks indicate the sides of a channel so you can know your way into a harbour, river or shoreline. For the IALA – A system, the port marks are red and have a top that can be flat or can-shaped and it has a red light at night. Starboard marks are green and come with a cone that points to the top or a triangle top. It flashes green at night.

When your boat is going in (away from the sea), the port mark will always be on the left side and the starboard mark on the right. Going out (towards the sea) will be the opposite, with the port mark on the right and starboard mark, on the left.

The general idea is to travel in between the lateral marks. In case there is just one lateral mark, then the correct side to travel depends on the direction you’re heading. When going upstream, you can keep the port marks on your boat’s port side (left). If it is downstream, it’s better to keep the port mark on your boat’s starboard side (right).

The IALA – B difference

The port marks still look the same but it has a green colour and flashes green light at night. The starboard mark is red and its light with the same colour.

The only significant difference that IALA – B has from the IALA – A is that the colours are assigned to the opposite sides. All other marks are identical in these systems.

Cardinal Marks

This mark indicates a hazard. It also shows in which direction you should travel using a compass. You will see it has black and yellow bands with two black cones as the top mark and, a single white light. Pay attention to the cones (triangles at the top of the signs) and the frequency in which the light flashes as these will indicate which direction is safe to travel.

  1. North Mark – These have two top cones pointing upwards with a white light that flashes quickly.
  2. South Mark – Two cones at the top point downward and it flashes white light six times quickly and a long flash follows every 10-15 seconds.
  3. East Mark – The top cones have the shape of an egg with a white light that flashes three times every five or 10 seconds.
  4. West Mark – The position of the cones at the top is similar to the shape of a wine glass. Its white light at the top flashes nine times very quickly for 10 – 15 seconds.

Isolated Danger Marks

This mark has black with red bands with a top mark that has two balls above each other. It flashes a single white light by twos at night. You have to be more cautious when you see this mark and avoid passing all sides near it. This is a hazard indicating a wreck or a rock.

Safe Water Marks

These marks have vertical red and white stripes and, a red sphere at the top. It has one long white light flash every 10 seconds. Seeing these marks means it is safe to pass in every direction. You can commonly find these in fairways, mid-channel or approaching land from the open sea (landfall mark).

Special Marks

These marks are used to indicate a location of cables and pipelines or to show where a channel splits into two. It is sometimes used in combination with lateral marks to show larger ships towards wider passages of a channel. You will know it is a special mark if it is yellow and has an X at the top. The flashing light used for these is also yellow and it is active at night. The sequence of flashes varies depending on the place.

Emergency Wreck Marking Buoy

These are also called “new danger marks”. The main purpose of this is to let everyone know there are new dangers or wrecks on the site that aren’t yet indicated in nautical charts. You can identify a new danger mark by its blue and yellow vertical stripes with a pillar or spar shape with a yellow cross as the top mark. Its blue and yellow light flash for one second alternately with a 0.5 second period of darkness.

Need a new boat?

Now that you’re familiar with navigational marks, you’ll be able to navigate your vessel safely. If you’re in the market for a new boat, Aussie Boat Loans can help you with boat finance. They have agents that will make sure you only walk away with a loan you can afford. Call today on 1300 769 999 or fill out the online application form.

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