A guide to the navigation aids we really need to know and what their chart symbols look like on the water
All navigational lights and buoys around the world come under the jurisdiction of the International Association of Lighthouse Authorities (IALA). It was only as recently as 1980 that the IALA agreed to reduce the number of systems of buoyage around the world from nearly 30 to two. Some would say even two is one too many, but that’s what we’ve got.
The system we use in the waters of the British Isles is IALA System A, with port shown by the colour red and starboard by green. It covers Europe, Africa, the Middle East, Asia, Australia and New Zealand. IALA System B, with port shown by the colour green and starboard by red, covers North America, Central America, South America, the Philippines, Japan and Korea.
Regardless of which system you use, there are six types of navigational marks – cardinal, isolated danger, emergency wreck, safe water, lateral and special. People refer to marks as beacons, but the definition of a beacon is “a lighted or unlighted fixed aid to navigation, attached to the earth’s surface”. If a mark stands on a post stuck in the seabed, it is shown standing vertically on a chart.
If floating, it is a buoy, and will be shown leaning just to the right. Here we’ll look at all of them, with some useful memory joggers to help us remember what means what. I hope any new boatowners will find the following useful; while after a winter ashore, there’s never any harm in a quick recap for the rest of us.
Safe water marks
When we come off passage, the first mark we come across is the safe water mark, also known as a fairway buoy. This tells us where “safe” water is, for instance a dredged channel, and announces the start of lateral buoyage. We can pass this on either side, although by convention we keep it to port. That way we’ll always be travelling down the right hand side of the channel.
Safe water marks:
- Can be spherical, a pillar or a spar
- Will always be candy-striped red and white
- If fitted with a topmark, will have a red ball
- Can also have either a bell or a whistle and a light.
At dusk or after dark, a safe water mark light can have a long flash every 10 seconds (LFL.10s), it can be occulting (it’s on more than it’s off ), or it can be isophase (equal phases of on and off ), or it can signal Morse A (dit dah, or one short then one long flash).
Buoys indicate the “preferred” option when a channel splits in two. The port hand mark pictured below has a green strip around its middle, telling us we can go to port of it (which would see us travelling left to right past the far side of pontoon B1), but the preferred channel is to starboard.
By going to port of this mark, you’ll end up in Hamble Point marina, near Southampton. If you want to go up the Hamble river, you need to go to starboard of this mark.
At night these lights flash twice and then once, or two plus one, written as FL(2+1)R.
Port and starboard buoys mark the sides of a channel and are arranged for entry into port. If there might be any doubt, for instance somewhere like the Solent, with two entrances, the general direction of buoyage is shown on the chart by a large magenta arrow with two circles.
Port hand markers can be anything from an upturned red bucket to the more sophisticated East Lepe in the Solent, which has a light and a bell. If navigating after dark or if you’re still out as dusk falls, you’ll see, if the buoy has lights, its flashing rhythm. This is shown on the chart, and in a run of buoys of the same type, each will have a different rhythm so you can tell them apart.
Your chart or almanac will explain what these denote, but it could be:
- Traffic separation scheme
- Spoil ground
- Military exercise zone
- Cables, pipeline
- Outfall pipe
- Recreation zone, such as waterski area
- Racing mark
- Ocean Data Acquisition Systems (ODAS), gathering information such as wind speed, pressure, salinity or temperature
- They are always yellow and sometimes marked with an X. If lit, the light will be yellow and usually a rhythm of FL.Y (flashing yellow) or FL.Y4s (flashing yellow once every 4s)
There are three types of danger marks – cardinal marks, isolated danger marks and emergency wreck marking buoys. It is easy to recognise them and remember what they mean when looking at photos in a classroom, but once afloat, even in good conditions, the reality is often less clear.
Being able to spot a danger mark, by day or night, and knowing which side to pass should be second nature to all motorboaters.
Named after the four cardinal points of the compass, cardinal marks tell you where safe water is. It’s important to be able to identify a cardinal either by its topmark or by its colour, but bear in mind top marks can go missing and often cardinals become faded or indistinct in colour. By day, often the top mark is the only thing that tells us what we’re looking at.
Cardinals have two cones as a topmark and their alignment defines the mark. Cardinals are coloured with black and yellow horizontal bands. The position of the black band or bands relates to the points of the black topmarks as follows:
How to remember your cardinals
Remembering north and south cardinal topmarks and their colours is not generally a problem, but sometimes we need a reminder about east and west.
The shape the cones make when facing away from each other reminds us of an egg, a word that starts with an E, as does ‘east’. As to colour, the yoke in the middle of the egg is yellow, similar to the colour of the cardinal – yellow in the middle with black above and below.
Some people like to remember the colours by thinking of the point of each cone pointing to black, with the fatter part of the cone yellow. Consequently, you have the yellow band in the middle, with black above and below.
The points of the cones face inwards, forming a rough W on its side – W for west. Some people like to look at it straight on and see a ‘waist’ between the cones, another reminder of the W and of the word west.
For the colours, sometimes sailors think of a black belt around the middle, signifying the black band with yellow above and below. As before, if the cones always point to black, then the cones on a west cardinal pointing inwards correspond to the black band in the middle of the two yellows.
Emergency wreck marking buoys
The authorities use these to warn shipping of a recent wreck. Later, if the wreck is not cleared away, it will either be allocated cardinal marks or an isolated danger mark. A wreck marking buoy carries blue and yellow stripes, with a cross for the top mark. At night it will have a blue and yellow alternating light, written on the chart as Al.BuW.
Isolated danger mark
This warns us of any danger, such as a rock or a wreck, around which there is navigable water. It will be erected on the danger, or moored above or very near to it. It has a top mark of two black balls, while the post is coloured black with one or more horizontal red bands.
These marks are shown on the chart with the two balls for the top mark and underneath BRB for the colour of the post
If an isolated danger mark has a light, it will flash twice during its sequence. This might be shown on a chart as FL.(2)5s. The light will be white. Generally, a light is always white unless the chart tells you otherwise. So if there is no information given about the colour of a light, it will be white. Red lights will be marked R, green lights G, yellow lights Y and blue lights Bu.
We should be able to identify a cardinal by its topmark or colour. The post of this cardinal is so covered in guano that we have no idea of its colour, while below, the cardinal’s top mark is missing.
Originally published in Motor Boats Monthly, June 2014, p48-51.
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