Lesson 5 of 13 · Module 2 — Finding your way

Lateral marks: Region A and Region B

Red to port in the Mediterranean, red to starboard in the Caribbean: the one rule that catches charter skippers out, with shapes, lights and preferred channels.

Day Skipper18 minVideo · Notes · Interactive · Exercises

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0:00 / 4:45Chapter 1 of 10: Signposts at sea

Transcript

Buoys and beacons are the road signs of the sea. They mark the edges of channels, warn of rocks and shallows, and lead you into harbour. Nearly every country lays them to one scheme, the IALA buoyage system. But the world is split into two regions, A and B, and the difference between them catches charter skippers out every summer.
Lateral marks show the two sides of a channel: port on one side, starboard on the other. But your port side becomes your starboard side when you turn round, so the marks need an agreed direction. That is the direction of buoyage: the way you go when you come in from the sea, towards a harbour, a river or a bay. Along open coasts the authorities set it, and the chart shows it with a magenta arrow wherever it is not obvious.
Start with Region A, which covers every Mediterranean charter area, the Seychelles and Thailand. Going in, with the direction of buoyage, the marks on your port side are red. A port-hand mark is usually a can, with a flat top, and if it has a topmark, that is a red can too. The marks on your starboard side are green, usually cone-shaped, with a green cone on top, pointing up. So in Region A, going in, it is red cans to port and green cones to starboard.
Here is the approach to Port Kerran on the practice chart, which is laid out in Region A. Coming in from the sea, you head north up the channel, with the direction of buoyage. The green cones, number one and number three, pass down your starboard side. The red cans, number two and number four, pass down your port side. Keep between them, and do not cut the corners, because the marks show the edge of the channel only where they stand.
At night you see only the lights, and on a lateral mark the colour of the light matches the colour of the mark. So in Region A, a red light is a port-hand mark and a green light is a starboard-hand mark. The rhythm tells you which buoy is which: number one flashes green once every five seconds, and number three flashes green twice. Count the flashes, time the cycle, and match what you see to the chart.
Leaving harbour, you are going against the direction of buoyage, so everything reverses. The red marks now pass down your starboard side, and the green ones down your port side. The marks have not changed, you have turned round. Say it out loud before you slip the lines: going out, red to starboard.
Where a channel divides, a lateral mark with a broad band of the other colour shows the main, or preferred, channel. Read its main colour and its shape, and treat it as that mark. A red can with a green band is a port-hand mark in Region A, so keep it to port, and the preferred channel lies to starboard. At night it shows a light in its main colour, flashing two, then one.
Now cross the Atlantic. The Americas, including the British Virgin Islands and the rest of the Caribbean, use Region B, and so do Japan, South Korea and the Philippines. In Region B the colours swap sides: going in, the red marks are on your starboard side and the green ones on your port side. Americans remember it as red, right, returning: red on your right as you return from the sea. The shapes do not swap, so going in, the cans are still to port and the cones to starboard. In the British Virgin Islands, then, a red cone is a starboard-hand mark and a green can is a port-hand mark.
Before every charter, check which region you will be sailing in. Croatia, Greece, Italy, Spain, Corsica, Montenegro and Turkey are all Region A. So are the Seychelles and Thailand. The British Virgin Islands are Region B, so on a Caribbean charter you keep red to starboard coming in. The rest of the system, the cardinal, danger, safe water and special marks, is the same in both regions.
Into a low sun every buoy looks black, but the shapes still show: a can is port-hand and a cone is starboard-hand, in either region. So find the direction of buoyage, then read the shape, then the colour. In Region A, going in, it is red to port, and in Region B it is red to starboard. Next, the yellow and black cardinal marks, and the rest of the family.

In this lesson you will learn

Say which IALA region each charter area uses, and what changes between Region A and Region B
Find the direction of buoyage, and keep each lateral mark on the right side going in and coming out
Recognise port-hand and starboard-hand marks by shape, colour, topmark and light, in either region
Read a preferred channel mark and say which way the main channel lies

Signposts at sea

Buoys and beacons are the road signs of the sea. A buoy floats, moored to the seabed, so it swings a little with the wind and current. A beacon is fixed: a pole, post or small tower standing on a rock or the seabed. Both are marks. Many carry a topmark, a small shape on top, and many are lit at night.

Almost every country lays its marks to one scheme: the IALA Maritime Buoyage System. It has lateral marks (this lesson), and cardinal, isolated danger, safe water and special marks (Lesson 6). The world is split into two regions, and they differ in one thing only: the colours of the lateral marks.

	Region A	Region B
Where	Europe and the Mediterranean, Africa, most of Asia, Australia and New Zealand	North, Central and South America and the Caribbean, Japan, South Korea and the Philippines
Our charter areas	Croatia, Greece, Italy, Corsica, Mallorca, Montenegro, Turkey, the Seychelles, Thailand	The British Virgin Islands (and all the Caribbean)
Port-hand marks	Red, can-shaped	Green, can-shaped
Starboard-hand marks	Green, conical	Red, conical
Every other mark	The same in both regions	The same in both regions

Region A, going into harbour: red to port. Region B, going into harbour: red to starboard.

The direction of buoyage

Lateral marks (from the Latin for “side”) show the two sides of a channel: port-hand marks on one side, starboard-hand marks on the other. But your port side becomes your starboard side the moment you turn round, so the marks need an agreed direction to refer to: the direction of buoyage.

Near a harbour, river, bay or channel, it is the direction you take coming in from the sea.
Along an open coast the buoyage authorities set it, and the chart shows it with a magenta arrow wherever it might not be obvious.

Every rule about lateral marks is stated for a boat going with the direction of buoyage. Going against it, leaving harbour, everything reverses.

The Port Kerran approach on the practice chart, which uses Region A. The teal arrow (added for this lesson; it is not a chart symbol) shows the direction of buoyage: from seaward, north into the harbour. Green cones (odd numbers) on the starboard side, red cans (even numbers) on the port side.

Region A: port-hand and starboard-hand marks

Every Mediterranean charter area, and the Seychelles and Thailand, use Region A. Going in, with the direction of buoyage:

	Port-hand mark	Starboard-hand mark
Colour	Red	Green
Shape	Can (flat top); or a pillar or spar	Cone (pointed); or a pillar or spar
Topmark (if any)	Single red can	Single green cone, point up
Light (if any)	Red, any rhythm except Fl(2+1)	Green, any rhythm except Fl(2+1)
Going in	Keep it on your port side	Keep it on your starboard side

A can is an upright cylinder with a flat top; a cone comes to a point. Bigger marks are often pillar buoys or spars, whose shape says nothing, so the topmark and colour do the work. In harbour entrances you will also see lateral marks as painted beacons or lights on the ends of the breakwaters: red on the port side going in, green on the starboard side.

Into Port Kerran

The practice chart is laid out in Region A. The approach to Port Kerran is a short buoyed channel running north: first the pair No 1 (a green cone, east side) and No 2 (a red can, west side), 5.4 cables apart, then 6.5 cables on, No 3 and No 4, 4.9 cables apart. Coming in you head north with the direction of buoyage, so the green cones pass down your starboard side and the red cans down your port side. The leading lights, in line on 000°T, take you straight up the middle.

Here, as on many Region A charts, the starboard-hand marks have odd numbers and the port-hand marks even ones, counting up from seaward. It is common practice rather than a rule, so always read the numbers from the chart.

Lights at night

At night you see only the lights. A lateral mark’s light is the same colour as the mark, so in Region A red is port-hand and green is starboard-hand. To tell one buoy from its neighbour, read the rhythm printed beside it on the chart: Fl is a single flash, Fl(2) flashes in groups of two, Q is quick flashing, and the number with an s is the period, the time the pattern takes to repeat.

Buoy	Light	Entering, keep it
No 1 Starboard-hand, green cone	Fl G 5s green: one flash every 5 seconds	To starboard
No 2 Port-hand, red can	Fl R 5s red: one flash every 5 seconds	To port
No 3 Starboard-hand, green cone	Fl(2) G 5s green: groups of two flashes every 5 seconds	To starboard
No 4 Port-hand, red can	Fl(2) R 5s red: groups of two flashes every 5 seconds	To port

Worked example

A light ahead: red, in pairs, every five seconds

1Kerran is in Region A and the light is red, so it is on a port-hand mark.
2Its flashes come in pairs, and the pattern repeats every 5 seconds: Fl(2) R 5s.
3On the chart that is No 4, the inner port-hand mark. No 2, the outer one, shows a single flash: Fl R 5s.
4You are entering, going with the direction of buoyage, so keep it on your port side.

No 4: keep it to port. You are nearly through the channel.

Leaving harbour: everything reverses

Leaving harbour you go against the direction of buoyage, so in Region A the red port-hand marks pass down your starboard side and the green ones down your port side. The marks have not changed; you have turned round. Say it to the crew before you slip the lines: going out, red to starboard.

InteractiveWhich side? In and out, in either region

Take the boat in and out again. For each mark, choose which side of the boat to keep it, then see where your choice takes you. Region A uses Port Kerran on the practice chart; Region B uses an example channel laid out as in the Caribbean. Try it by day, into the sun (only shapes show) and at night (only lights).

Region A · mark 1 of 8 · 0 right first time

Your chart: Port Kerran (practice chart, Region A)

The dashed line is your track so far. Once you answer, the chart shows which buoy it was and where your choice takes you.

From the boat: the next mark

Entering Port Kerran from seaward: heading 000°T, with the direction of buoyage.

Which side of the boat do you keep this mark?

Preferred channel marks

Where a channel divides, a lateral mark with one broad band of the other colour can show which branch is the preferred, or main, channel. Read its main colour and shape and treat it as that mark:

Region A	Looks like	Treat it as	Preferred channel
Preferred channel to starboard	Red with one broad green band; can; Red, Fl(2+1)	Port-hand: keep it to port	To starboard of it
Preferred channel to port	Green with one broad red band; cone; Green, Fl(2+1)	Starboard-hand: keep it to starboard	To port of it

In Region B the colours swap as usual: the preferred-channel-to-starboard mark is a green can with a red band, and the preferred-channel-to-port mark a red cone with a green band. In both regions the light matches the main colour and flashes two, then one: Fl(2+1), a rhythm lateral marks keep for preferred channels.

Region A

Preferred channel to starboard

Preferred channel to port

Region B

Preferred channel to starboard

Preferred channel to port

Preferred channel marks in each region: to starboard (left) and to port (right).

Check your understanding: in Region A, going in, you reach a fork. On the dividing point is a green conical buoy with one broad red band. Which branch is the preferred channel?

Region B: red right returning

The Americas use Region B, and so does the whole Caribbean, including the British Virgin Islands, even though they are British. So do Japan, South Korea and the Philippines. In Region B the colours of the lateral marks swap sides; nothing else changes.

Region A

Port-hand mark

Starboard-hand mark

Region B

Port-hand mark

Starboard-hand mark

Going in, with the direction of buoyage: the port-hand mark (left) and starboard-hand mark (right) in each region. The shapes stay; the colours swap.

Going in, red is on your right: “red, right, returning”, returning from the sea.
The shapes do not swap. Cans are still port-hand and cones starboard-hand. Americans call the cone a nun.
Numbers often swap too: in the Americas, red marks usually carry even numbers and green marks odd numbers, counting up from seaward.
Leaving, everything reverses, exactly as in Region A: going out, red to port.

Worked example

Into Setting Point, Anegada

1Anegada, in the British Virgin Islands, is ringed by reef, and the way in to Setting Point is a marked channel. Many charter companies allow it only in good light, if at all.
2The BVI are Region B. Coming in from the sea you go with the direction of buoyage: red marks on your starboard side, green on your port side.
3Check each mark’s shape as well as its colour: a cone is starboard-hand, a can port-hand, whatever the light is doing to the colours.
4Going out the next morning, it reverses: red to port.

Red right returning. And follow the charter company's briefing for Anegada: the reef has wrecked many boats.

Which region is your charter in?

InteractiveRegion finder

Pick a charter area from our cruising guides to see its buoyage region and what you keep where going in.

Croatia: Region A

Charter base: Kaštela, near Split

Going in: red to port, green to starboard.

Region A, like the rest of the Adriatic. Marked channels are short; most marks you meet guard rocks and shoals off headlands and islands.

InteractiveLateral mark identifier

Explore the lateral marks in either region by day, into the sun and at night. Then press Test yourself to identify marks from a picture or a light; each one tells you which region you are in.

Port-hand mark, Region A

Colour: Red
Shape: Can (flat-topped), pillar or spar
Topmark: Single red can
Light: Red, any rhythm except Fl(2+1)

Marks the port side of the channel. Going with the direction of buoyage, keep it on your port side; leaving harbour, it passes down your starboard side.

When colours let you down

Looking into a low sun every buoy is a black outline, and at dusk or in haze red and green are hard to tell apart. That is why lateral marks differ in shape as well as colour: can for port, cone for starboard, with topmarks to match, in both regions.

Into a low sun the colours vanish, but the shapes do not: a can with a can topmark (left) is a port-hand mark, and a cone with a cone topmark (right) is a starboard-hand mark, in both regions.

Find the direction of buoyage first. Then read the shape, then the colour. Region A going in: red to port. Region B going in: red to starboard.

Next: cardinal marks, which tell you where the safe water lies around a danger using the compass instead of port and starboard.

Key terms

IALA Maritime Buoyage System: The international scheme of buoys and beacons, used worldwide in two regions, A and B.
Region A: Europe and the Mediterranean, Africa, most of Asia, Australia: going in, red marks to port. All our Med charter areas, the Seychelles and Thailand.
Region B: The Americas and the Caribbean (including the BVI), Japan, South Korea, the Philippines: going in, red marks to starboard.
Red right returning: The Region B memory aid: red marks on your right as you return from the sea.
Lateral mark: A mark showing the port or starboard side of a channel.
Direction of buoyage: The direction lateral marks refer to: in from the sea; along open coasts set by the authorities and shown by a magenta arrow on the chart.
Port-hand mark: A can-shaped mark kept to port going in: red in Region A, green in Region B.
Starboard-hand mark: A cone-shaped mark kept to starboard going in: green in Region A, red in Region B.
Preferred channel mark: A lateral mark with a broad band of the other colour, where a channel divides; light Fl(2+1). Treat it by its main colour and shape.
Period: The time a light's pattern takes to repeat, such as 5 seconds (5s).

Exercises

Check your understanding. You get a second try at each question, then the worked answer. Score 70% or more to complete the lesson; your progress is saved in this browser.

You are entering a harbour in Croatia (Region A), going with the direction of buoyage. A red can-shaped buoy lies ahead. How do you pass it?

In Greece (Region A), which of these is a starboard-hand mark?

On a charter in the British Virgin Islands (Region B), you are entering a bay by its marked channel. A red cone-shaped buoy lies ahead. Which side do you keep it?

Leaving Road Town on Tortola (Region B) for the open sea, you pass a green can buoy. Which side do you keep it?

In Region A, going with the direction of buoyage, you reach a fork in the channel. On the dividing point is a red can buoy with one broad green band, light Fl(2+1) R 10s. What does it tell you?

Which of these charter areas uses IALA Region B, where you keep red marks to starboard coming in?

You are entering Port Kerran on the practice chart (Region A) from seaward. Tap the buoy at the inner, harbour end of the channel that you keep on your port side.

Entering Port Kerran at night, you see this light ahead: Fl(2) R 5s. Which buoy is it, and which side do you keep it?

red, group flashing, 2 flashes every 5 seconds0.0 s of 5 s

No 3 buoy shows Fl(2) G 5s: groups of two green flashes, repeated every 5 seconds. How many flashes does it show in one minute?

Heading into a low evening sun, you cannot make out any colour, but this buoy's outline is clear. You are going with the direction of buoyage. What is it, and which side do you keep it?

You are leaving Port Kerran for the open sea. Tap the last buoy you keep on your port side before you clear the channel.

0 of 11 answered · 0 correct

Which side, which region?

Five fresh questions each time: marks in both regions by day and into the sun, lights at night in Port Kerran, a buoy to find on the chart, and the region of a charter area.