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Lesson 10 Buoyage System

In Europe we have on the sea the IALA-A system. There are lateral buoys (on the sides of channels) and cardinal buoys (indicating a wreck, sandbank or other obstacle). Buoys are floating. Beacons are fixed in or on the ground. There are buoys with and without a light and/or top mark. Spar buoys are narrow, so they are less affected by wind, tidal current or ice. In the shallow waters of Holland branches are used to mark waterways. When the branches are tied together it means it is a conical shape (green in Europe). If the branches are not tied together, it is a cylindrical shape (red in Europe).


Shape = (Round, conical, cylindrical, pillar)
Licht characteristic and color
Top mark
Color (green, red, black, yellow, white)
Radar reflector
Name: often the name of the water

Light characteristics

In general we can say that the quicker the flashes, the more dangerous it is.
The different light characteristics are:

Q = Quick Flash (VQ = Very Quick en UQ = Ultra Quick)
Fl = Flash (Lfl=Longflash)
ISO = Isophase (ISO 2s = 1 seconde aan en 1 seconde uit)
Oc = Occulting (group occulting means the light will be occulting multiple time in one period)
Mo = Morse code
F = Fixed



The buoyage direction in het IALA-A systeem (European seas) in the direction of the port. We often first see a safe water mark, marking the beginning of the channel. If we sail into a port we will have the green buoys at our starboard side and the red buoys at our port side. The green buoys are conical and odd numbered. The red buoys are cylindrical and even numbered. We always enter a port with the green board light (starboard) on the green buoys and with our red board light (port) on the red buoys.

GROS: Green Right On Starboard (entering a harbour.)


Sailing into a harbour at portside we see a red white horizontal striped beacon and at our starboard side a green white horizontally striped beacon.
havenhoofdhavenhoofd sb

Recommended yacht track

Recommended yacht tracks are like a bike-lane next to a channel with big ships. The yacht tracks are marked with small lateral buoys.
aanvullende markering

Leading lights

When we look at the port, we can use the leading lights to see if we are sailing in the middle of the channel, by looking at the leading lights. These are for example 2 lighthouses of which the first one is lower than the second. If we see the 2 lights perpendicular above each other, we are in the center of the channel on the light line.

If objects other than lights are used, we call it a leading marks, as shown in the picture below, a white patch on the coast in line with the white hotel on the hill behind it. Sometimes the channel is indicated with a sector light. This is a light that shines a different color over the different sectors. We can see in the nautical chart when we are for example in the channel, we see white light. When we are sailing on the right of the channel, we see a green light and when we are sailing to the left, we see a red light.

Cardinal buoyage

Cardinal buoyage marks obstakels. A North Cardinal for example means: safe at the North side and an obstacle at the South side of te buoy.

The top marks point to the black color on the buoy, that is always black and yellow. The light characteristics are like the hours on a watch.

The Long Flashing distinguishes the South Cardinal from the West Cardinal, as in high waves the difference between 6 or 9 flashes could be difficult to see.
kardinale markering

noord kardinaal


If a channel divides into two in the IALA-A system there will be a:

  1. Laterale Bifurcation buoy
  2. Cardinale Bifurcation buoy

Example 1: Red Laterale Bifurcation buoy with the preferred channel on the right / east side


Example 2: Green Laterale Bifurcation buoy with the preferred channel on the left / west side


Example 3: Cardinal Bifurcation buoy.


Cautionary buoys

These mark a special area, for anchoring, military, fishing, speedboats, regattas, etc. The color is yellow and the top mark is a cross.
bijzondere markering

Isolated danger buoy

An isolated danger is marked by a black buoy with a red belt. The top mark exists of two balls. The light is white group flashing.
afzonderlijk gevaar

Mid channel buoy

These marks are in the middle of the channel. They are red white vertically striped. The light is a ISO 8s or LFL. In case the buoy marks the beginning of a channel it is called a landfall buoy or sea buoy.
veilig vaarwater

Emergency wreck marking buoy

These marks are yellow and blue vertically striped. The light is an alternating blue yellow flashing B1.0s+0.5s+Y1.0s+0.5s= 3.0s

nieuw gevaar



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Questions & explanations

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Question 1: In case you see the highest of the leading lights more to the right you need to go...


a: to starboard

b: to port

c: keep course

Question 2: An isophase light is a light that shines .... compared to darkness. 


a: longer

b: shorter

c: just as long

Question 3: Sailing in the shipping lane of the English Channel heading for Holland you will see these marks at your starboard side:


a: red cylindrical marks

b: green conical marks

c: green cylindrical

Question 4: What does a yellow buoy with a cross mean? 


a: isolated danger

b: channel

c: special area

Question 5: At which side you need to pass a buoy that is black on top and yellow at the bottom?


a: North

b: East

c: South

Question 6: A buoy: yellow - black - yellow, means that the safe side is on:


a: the East side

b: the West side

c: the South side

Question 7: What is the meaning of a yellow blue vertical striped buoy? 


a: isolated danger

b: prohibited area

c: new danger

Question 8: A red white vertical striped buoy is a:


a: landfall buoy

b: Mid channel buoy

c: both are correct

Question 9: What is at night the light characteristic of a beacon that is yellow on the upper part and black on the lower part?


a: Q

b: Q(6) + LFL 15s

c: Q(9) + LFL 15s

Question 10: What is the meaning of a buoy that is black on the upper part and yellow on the lower part? Safe at ...:


a: East side

b: South side

c: North side

About Elmar Teeuwen

Elmar is a CWO sailing instructor and RYA Yachtmaster® Offshore, Commercial Endorsement with STCW95 and certified coastal navigation teacher.
He has more than a decade of experience with teaching sailors on the North Sea, Atlantic, Med and Caribbean from beginners to instructor level, as well as regatta teams.
In addition to his native language Dutch, Elmar speaks English, German and Italian.
His knowledge and teaching skills could be off great value to anyone who wants to realise his sailing dreams.