A guide to IALA (A) Buoyage

A guide to IALA (A) Buoyage


Below is a series of photographs taken in the Solent that cover all types of buoy encountered in IALA (A) regions. That is most of the world with the exception of north, central and south America.Japan and the Philippines. It is aimed as a guide for RYA Day Skipper students and any one who is interested in understanding the meaning of buoys. The colours shown below will be the same whether the marks are buoys or posts.

Channel buoys

Starboard Hand Buoy.

Starboard hand buoys marking a channel are almost always green and conical in shape with a conical topmark. At night they may exhibit a green flashing light with varying flashes to aid identification. These would be left to starboard when entering a channel, port or harbour. If channel buoys are numbered starboard hand buoys will have odd numbers with  number 1 being the first one to mark the channel at its outer end. On the chart they are annotated G.




The shape and topmark help identify the buoy when it is a long way off or has the sun behind it. In this picture it is very difficult to see the colour but it is obviously conical with a conical topmark so there is no doubt it is a starboard channel mark.



Port Hand Buoys.

Port Hand buoys are almost always red and are "can" shaped. Normally they would have a "can" shaped topmark as well but in this photograph the topmark is missing. At night they may exhibit a red flashing light with varying flashes to aid identification. These would be left to port when entering a channel, port or harbour. If channel buoys are numbered port hand buoys will have even numbers with  number 2 being the first one to mark the channel at its outer end. On the chart they are annotated R.



This photograph shows how shape will help identify the buoy. With the sun directly behind the buoy it is impossible to tell the colour even though the boat is quite close to the buoy.




Preferred Channel Buoy.

This photograph shows a post which indicates that the preferred channel is to starboard. Preferred channel marks are placed at junctions where two channels join. In this case the preferred channel (going into the harbour) is to starboard but there is a minor channel into a marina going to port of the post. A preferred channel to starboard essentially means that it is marking the port side of the main channel so the predominant colour is red but it also has a green band in the centre. A preferred channel to port will be predominately green with a red band in the centre. If lit these would flash either red or green 2 + 1. This one would flash Fl R (2+1) but a preferred channel to port would be Fl G (2+1). A preferred channel to starboard is marked on the chart as RGR whilst a preferred channel to port is marked as GRG.

Cardinal Marks

Cardinal Buoys are so called because they are placed around an area of danger in accordance of the main points of the compass; north, east, south and west. They are all coloured black and yellow  and have two black conical topmarks. The orientation of the topmarks and arrangement of colour indicate which side of the danger they are placed. If lit all will have a quick or very quick flashing white light with the flashing sequence showing which side of the danger they are placed.

East Cardinal Buoy

An east cardinal buoy is placed to the east of the danger and so should be passed on its eastern side away from the danger. It has its topmarks arranged so that the top one is pointing up and the bottom on is pointing down. As an "aide memoir" just think that the topmarks form the shape of an egg so E for egg and E for east cardinal. The topmarks also indicate where the black will be placed on the buoy. The top cone points up so there will be black at the top of the buoy and the bottom one points down so there will also be black at the bottom of the buoy with a yellow band around the middle. If one thinks that east is at 3 o'clock on the compass rose it will remind one that east cardinals will, if lit, will flash Q (3) or VQ (3). They are marked on the chart as BYB.

South Cardinal Buoy

A south cardinal buoy is placed to the south of the hazard and so should be passed on its south side. A south cardinal buoy has both topmarks pointing downwards (or to the south). With both topmarks pointing downwards it indicates that black will be at the bottom with yellow at the top. With south being at 6 o'clock of the compass rose south cardinals will flash 6 times but as it is difficult to count six. there is always a long flash after the 6. They will always flash Q (6) + L Fl or VQ (6) +L Fl. The colours will be marked on the chart as YB.

West Cardinal Buoy

A west cardinal buoy as expected is placed to the west of the hazard so pass to the west of it. It has the topmarks pointing towards each other and are similar in appearance to a "wasp waist". W for wasp and W for west. As the cones also indicate the position of black on the buoy the buoy will be predominately yellow with a black band in the centre. As west is in the 9 o'clock position on a compass rose this will flash nine times, either Q (9) or VQ (9). On the chart the colours will be marked as YBY.


North Cardinal Buoy

A north cardinal buoy would be placed to the north of a hazard so always pass to the north of it. Both topmarks point up (or to the north). Again the topmarks indicate where the black colour will be on the buoy and in this case it is black at the top and yellow at the bottom. Note on this photograph that there is some weed growing at the base of the buoy.It is not too bad here but if the buoy has not been maintained for a long time the growth may be worse than this and, from a distance, it may appear to be a east cardinal. Simarly deposits from seagulls,although not obvious here, may make the buoy appear as a west cardinalfrom a distance. The topmark will always indicate which cardinal buoy it is. As north is at 12 o'clock on the compass rose it may be expected to flash in groups of twelve. However as it would be impossible to keep count of twelve flashes north cardinals flash continuously, either Q or VQ. The colour is marked on the chart as BY.



Other Marks

Isolated Danger Mark.

Isolated danger buoys or posts are placed over a relatively small danger area, for example a small rock or a wreck. They are coloured red and black in horizontal bands and the topmark is two black balls as shown in the photograph. However, just to confuse the viewer a cormorant has taken a rest on the top ball! Isolated danger buoys have 2 white flashes when lit. Fl (2) The colours on the chart will be marked BRB.



Fairway Buoy or Safe Water Buoy

Safe water buoys or posts are placed in the entrance to a port or harbour and mark the centre of the deep water channel. They are usually white and red stripes with a red or red and white striped spherical topmark. The photograph to the left shows that marks do not always obey the rules. The post to the left is the fairway mark into Langstone Harbour which is a relatively small harbour used by fairly small commercial vessels. As can be seen it is a black post with a spherical red and white striped topmark. This can be seen better in the second photograph.The topmark is, in fact, the identifying feature of this mark. If lit they show a white


light, usually a long flash (L Fl) but may exhibit an occulting light (oc); longerlight periods than dark,  iso phase (Iso); equal amount of light and dark or Morse A (one short flash and one long flash). On the chart these will be marked RW.




Temporary Wreck Buoy.

A temporary wreck buoy is a fairly uncommon sight and for that reason there is no photograph. It is coloured blue and yellow and, if lit, will flash alternate blue and yellow light. They are placed to mark the position of a recent wreck and will subsequently be replaced with either cardinal marks or an isolated danger mark. If placed on the chart they will have the colour described as BY

Special Buoys

These are yellow in colour and, if lit, will flash a yellow light.  There are many differnt types of special mark from weather stations, tidal stream monitoring buoys, marking the position of traffic separation schemes to racing buoys. The colour of these is marked on the chart as Y.