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Buoyage: red, green and the four cardinals
Buoyage is a set of rules you understand once and then never look up again. The effort pays at night over an unfamiliar harbour entrance, which is exactly when there is no time to look anything up.
IALA A, the base rule
In Europe, Africa, Australia and most of Asia, region A applies: entering, red is to port and green to starboard. In the Americas, Japan and Korea region B applies, and it is the other way round.
Lateral marks
Red is can shaped, green is conical. You can still tell them apart when the colour is lost against the light. At night it is the character of the light that helps, the rhythm, not the colour alone.
Cardinal marks
The four say on which side of a danger the safe water lies, named after the compass point: you pass a north mark to the north of it. The topmarks are the aid, two cones: both points up is north, both down south, points apart east, points together west.
Isolated danger and safe water
Black with a red band and two black balls: isolated danger, safe to pass on all sides. Red and white vertical stripes with a red ball: safe water, often the landfall buoy off an entrance.
Buoyage trainer: which side do you pass?
A buoy rolls in the swell ahead, its light flashing in its real rhythm. Say where you pass it. Entering harbour, the direction of buoyage runs in from seaward.
IALA buoyage system A: direction of buoyage and reading the channel
IALA buoyage system A applies throughout Europe, so it covers every cruising ground around Britain, Germany and Spain. The core idea: coming in from sea into a harbour, estuary or channel, red marks are to port and green marks to starboard. That is called the direction of buoyage.
It gets less obvious along a coast or between two ports, where seaward and landward are not clear. There the authorities define the direction of buoyage, and the chart shows it with a dedicated arrow symbol. A look at that arrow before you leave saves guesswork on the water.
In a channel the marks are often numbered, red ones usually even and green ones odd, counted in the direction of buoyage. Checking the numbers against the chart tells you exactly where you are in the channel.
Lateral marks: shape, colour, topmark and light
Lateral marks show the sides of a channel. Port-hand marks are red, carry a red can topmark and show a red light at night. Starboard-hand marks are green, carry a green cone pointing up and show a green light. The lights may have any rhythm except the one reserved for channel divisions.
Where a channel splits you find preferred channel marks. A red mark with one broad green band means the preferred channel is to starboard, and you treat the mark as a port-hand mark. Green with a red band is the opposite. At night both show a composite group of two plus one flashes in their main colour.
Besides buoys there are spars, poles and fixed beacons in the same colours. In shallow waters and on lakes you may only find withies or posts. Inland waterways follow their own rules, which do not always match IALA A, so check which regulations apply before you set off.
Cardinal marks: colours, topmarks and light characters
Cardinal marks are black and yellow, and where the black sits follows the topmark: the points of the two cones point towards the black part. North is black over yellow, south yellow over black. East is black with a yellow band in the middle, west yellow with a black band.
At night cardinal marks show a white quick or very quick flashing light. The number of flashes is easiest to remember with a clock face: east sits at three o'clock, south at six, west at nine, and north at twelve flashes without a break.
Cardinal marks are also handy for getting your bearings again after a change in the weather or at night. If you know which side of the danger you are on, you can adjust course without any sums. Watch the tidal stream, which can set you sideways towards the hazard.
- North: both cones pointing up, continuous quick (Q) or very quick (VQ) flashes.
- East: points apart, groups of three flashes.
- South: both cones pointing down, groups of six flashes followed by one long flash.
- West: points together, groups of nine flashes.
Isolated danger marks, safe water and special marks
An isolated danger mark sits right on top of a small hazard, such as a rock or a wreck, with navigable water all round. At night it shows a white light with groups of two flashes. Give it a good berth anyway: only the chart tells you how far the danger extends under water.
The safe water mark is red and white with vertical stripes and shows a white light at night, for example isophase, occulting, one long flash or the Morse letter A. It often serves as a landfall buoy and can be passed on either side.
Special marks are yellow with a yellow X-shaped topmark and a yellow light. They do not mark a navigational danger as such but special areas: swimming zones, restricted areas, fish farms, measuring instruments or cable routes. The chart or the pilot book tells you what each one means.
Buoys and sea marks at night, and the emergency wreck mark
New wrecks not yet shown on charts get a dedicated emergency wreck marking buoy. It has blue and yellow vertical stripes, an upright yellow cross as topmark and at night shows alternating blue and yellow lights. It stays in place until the wreck has been promulgated and marked permanently.
At night buoys lose their shape. What remains is colour and rhythm. The character of every light is on the chart and in the list of lights. Count the flashes out loud and time the period with a watch before you match a light to a mark.
Many smaller buoys are unlit and can only be found at night with a searchlight or radar. Plan your first entry into an unfamiliar harbour for daylight where you can, and note the characters of the key lights on a card at the helm beforehand.
Frequently asked questions
Which side are the red buoys on?
In IALA system A, which applies in Europe, red marks are to port when entering from sea. Leaving harbour, it is the other way round.
How do I remember cardinal marks?
The cone points point to the black on the buoy. For the lights, think of a clock: three flashes for east, six plus a long one for south, nine for west, and north flashes continuously.
Which side do I pass a west cardinal?
To the west of it. Every cardinal mark is passed on the side it is named after.
What does a yellow buoy with an X mean?
It is a special mark, for instance a swimming area, a restricted zone or a fish farm. The chart tells you what it marks and whether you may enter.
What is a buoy with blue and yellow stripes?
That is an emergency wreck marking buoy for a new wreck not yet on the charts. Keep well clear.
Does sea buoyage apply on rivers and lakes?
Not always. Inland waterways have their own rules, some with different marks. Check which regulations apply before you go.
What this has to do with insurance
Grounding is one of the most frequent hull claims, and it rarely happens in open water but in entrances and over shoals. After a grounding the boat should be surveyed even if it seems tight: damage to rudder, shaft and keel bolts often shows weeks later, and by then the connection is harder to prove.
