IALA A Buoyage revision module 1 of 5

IALA

IALA A vs B Overview

What the buoyage system is, where Region A and Region B differ, and how to avoid mixing the lateral colours.

IALA systemRegion ARegion Bdirection of buoyage

7 guided lessons · 8 practice questions · 8 flashcards

3 outcomes · self-guided revision

Separate the main buoyage families and decide what evidence is still needed before a mark becomes a safe pilotage instruction.
State exactly which parts of the lateral system change between IALA Regions A and B and which recognition rules remain common.
Translate a lateral mark correctly after identifying whether the passage is in Region A or Region B.

A self-guided revision companion that explains essential concepts, then helps you practise and test them. It supports—but does not replace—recognised instruction, practical training, assessment or certification. Access is a one-time payment, not a subscription.

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Lesson routeWhat IALA Buoyage Is Trying To Tell You0/7 read

Lesson 1 of 7

What IALA Buoyage Is Trying To Tell You

What you will learn

Separate the main buoyage families and decide what evidence is still needed before a mark becomes a safe pilotage instruction.

A buoy is one part of a navigation picture. Begin with the mark family, combine its recognition cues, then use the charted situation and current local information to decide what it means for this boat.

IALA's maritime buoyage system groups marks by job. Lateral marks define the sides of a channel in the conventional direction of buoyage. Cardinal marks indicate the named compass side of a danger. Isolated-danger, safe-water, special and emergency-wreck marks each communicate a different relationship or purpose.

Colour alone is not a complete identification. Red and green matter within the lateral system, yellow can identify a special mark or form part of a cardinal pattern, and black can combine with yellow or red. Shape, topmark, light character, sequence and charted position provide the corroboration that a fleeting colour impression cannot.

Even a correctly named mark does not supply the whole route decision. Buoys can be missing, displaced, damaged or temporarily altered, and their charted positions may be approximate. Keep adequate distance, compare the mark with the current chart, depth, surrounding sequence and notices, and retain a safe alternative if the evidence does not agree.

Lateral-system comparison

Keep the side and shape; translate the colour

Conventional direction of buoyage

Region A

New Zealand, United Kingdom and much of Europe

Port-hand

Red · can / cylindrical

Starboard-hand

Green · cone / conical

Region B

Canada and the United States

Port-hand

Green · can / cylindrical

Starboard-hand

Red · cone / conical

Region A/B reverses lateral red and green. Port-hand still means the port side in the conventional direction and uses the can shape; starboard-hand still uses the cone shape.

The lateral colours change between regions; the port and starboard jobs and the can and cone shape language do not.

What IALA Buoyage Is Trying To Tell You
Mark family	Question it answers	Still check
Lateral / preferred channel	Which side or branch is defined in the direction of buoyage?	Region, direction, charted channel and vessel suitability
Cardinal	On which named compass side does safe water lie?	Danger extent, position and a usable route
Isolated danger / safe water	Is there a local danger or navigable water around the mark?	Charted feature, depth and surrounding hazards
Special / emergency wreck	Is a special-purpose area or newly marked wreck being indicated?	Chart symbol, notes, notices and local directions

Turn colours into a checked pilotage picture

Approaching unfamiliar water, the crew reports a red mark, a green mark, a yellow mark and a black-and-yellow mark ahead. The colours alone do not define one safe route.

1. Classify the family
Use shape, topmark, colour pattern and light if visible to distinguish lateral, special and cardinal candidates.
2. Locate the marks
Compare their observed order and relative positions with the current chart and the expected channel or danger.
3. Apply the right rule
Use region and direction only for lateral meaning; use the named safe-water side for a cardinal mark and the charted purpose for a special mark.
4. Retain margin
Choose an action suitable for the boat, depth, traffic and conditions, without passing unnecessarily close to a buoy.

Sense check: If the decision rests on one colour or one remembered phrase, the family and charted context have not yet been established.

Common mistake or limitation

Treating every buoy as a lateral mark that dictates a side of the channel.
Naming a mark from colour alone while ignoring shape, topmark, light and sequence.
Steering close to a buoy as though its position were an exact surveyed boundary.

Recap

Different mark families answer different navigation questions.
A reliable identification uses several agreeing cues, not colour alone.
The safe action still depends on charted context, the vessel and current conditions.

Optional quick check

Section 1 of 7

A yellow buoy is sighted near the planned route. What is the best first response?

Continue

Lesson 2 of 7

What Changes Between Region A And Region B

What you will learn

State exactly which parts of the lateral system change between IALA Regions A and B and which recognition rules remain common.

The A/B distinction changes the red-and-green colour meaning of lateral marks. It does not invert the whole buoyage system or change the port-can and starboard-cone shape convention.

The regional difference belongs to lateral marks. Region A assigns red to port-hand lateral marks and green to starboard-hand lateral marks in the direction of buoyage. Region B assigns green to port-hand marks and red to starboard-hand marks. Preferred-channel marks are also lateral marks, so their predominant red or green colours follow the regional lateral scheme.

The side meaning remains stable: a port-hand mark defines the port side and a starboard-hand mark defines the starboard side when proceeding in the conventional direction. The shapes also remain stable: a port-hand mark is can or cylindrical where shape is used, while a starboard-hand mark is conical. That second cue is especially valuable when colour is difficult to distinguish.

Cardinal, isolated-danger, safe-water, special and emergency-wreck families are not subject to the Region A/B red-green lateral reversal. Their shared IALA patterns still need chart and local context. National implementation, numbering and local direction conventions must be checked in current charts and publications rather than inferred from the region label alone.

What Changes Between Region A And Region B
Feature	Region A	Region B
Port-hand lateral colour	Red	Green
Starboard-hand lateral colour	Green	Red
Port-hand shape	Can / cylindrical	Can / cylindrical
Starboard-hand shape	Cone / conical	Cone / conical
Non-lateral families	Common IALA family logic	Common IALA family logic

Separate the variable from the constant

A skipper used to Region A prepares for a passage in Region B and is tempted to relearn every buoy family from scratch.

1. Isolate the change
Reverse the red-and-green lateral colour assignments, including the predominant colour of preferred-channel marks.
2. Keep the stable cues
Retain port-can and starboard-cone shape meaning and the established patterns of non-lateral families.
3. Verify locally
Use the current chart and national publications for the direction, numbering, alterations and local application.

Sense check: If the plan reverses cardinal colours or swaps can and cone shapes, it has extended the regional difference too far.

Common mistake or limitation

Saying that every buoy colour and family reverses between the two regions.
Forgetting that a preferred-channel mark is part of the lateral system.
Swapping the can and cone shapes as well as the red and green colours.

Recap

Region changes colour assignment, not the port and starboard jobs.
Use shape as an independent cue: port can, starboard cone.
Current national charts and publications still control the local application.

Optional quick check

Section 2 of 7

Which feature remains the same when moving from Region A to Region B?

Previous Continue

Lesson 3 of 7

Region A And Region B

What you will learn

Translate a lateral mark correctly after identifying whether the passage is in Region A or Region B.

Region is the first lateral-system context check. The United Kingdom uses Region A; Canada and the United States use Region B. The same side names are expressed with opposite red and green colours.

Trinity House states that the buoys it deploys around England, Wales and the Channel Islands conform to IALA System A. In the conventional direction of buoyage, a Region A port-hand lateral mark is red and a starboard-hand lateral mark is green.

The Canadian Coast Guard describes Canada as Region B: starboard-hand lateral marks are red and port-hand lateral marks are green in the upstream direction of buoyage. This is the opposite colour assignment, not an opposite definition of port and starboard.

Use a full spoken translation instead of a free-floating colour mnemonic: region, conventional direction, side, colour, then safe action. A slogan such as ‘red right returning’ describes a Region B convention and is unsafe if imported into Region A without first identifying the region and direction.

Region A And Region B
Region example	Port-hand lateral	Starboard-hand lateral	Translation
A — United Kingdom	Red; can/cylindrical	Green; cone/conical	Region A → direction → port red / starboard green
B — Canada	Green; can/cylindrical	Red; cone/conical	Region B → direction → port green / starboard red

Re-brief the crew before entering unfamiliar waters

A crew trained in the United Kingdom is approaching a Canadian harbour. One person remembers only that red marks were port-hand during UK exercises.

1. Name the region
Confirm from the current chart and national information that the passage uses Region B.
2. Name the direction
Establish the charted conventional direction before assigning a side to any lateral mark.
3. Translate the side
In Region B, port-hand is green and can-shaped; starboard-hand is red and conical where shape is used.
4. Check the scene
Confirm the observed sequence, charted channel, depth and traffic before choosing the route.

Sense check: A colour remembered from another country is not a side instruction until the region and direction have been established.

Common mistake or limitation

Applying a Region B returning mnemonic in Region A waters.
Remembering red or green without first naming the region and direction.
Assuming the opposite colours mean that port and starboard themselves have changed.

Recap

Region A and Region B reverse lateral red and green.
The side names and can/cone shape meanings remain stable.
A safe memory sequence is region → direction → side → colour → action.

Optional quick check

Section 3 of 7

In the conventional direction of buoyage in Canadian Region B, which combination identifies the starboard-hand lateral mark?

Previous Continue

Lesson 4 of 7

Direction Of Buoyage

What you will learn

Establish the conventional direction of buoyage from authoritative navigation information before interpreting a lateral mark.

Port-hand and starboard-hand lateral marks are named in the conventional direction of buoyage. That direction is set for the waterway; it is not automatically the boat's present heading, the tide or compass north.

The competent authority establishes the conventional direction for lateral buoyage and the current chart and publications show how it is applied locally. In many harbour and river approaches the general pattern is from seaward towards the harbour or upstream, but a remembered ‘inbound’ rule cannot resolve every junction, coastwise channel or locally defined waterway.

Direction of buoyage is a reference direction, not an instruction to steer a particular course. Your vessel may be crossing, leaving, turning through a bend or holding clear of traffic while the lateral marks keep the same charted identity. Tide direction, the direction the bow happens to point and compass north do not redefine them.

At a junction, confirm the main direction and identify whether a striped mark is a preferred-channel lateral mark before choosing a branch. The named preferred channel describes the branch relative to the mark in the conventional direction; it does not guarantee sufficient depth, clearance or suitability for your vessel.

Direction Of Buoyage
Candidate cue	Use	Limit
Current chart / authority publication	Primary source for the local conventional direction and alterations	Must be the applicable, current information
Approaching from seaward or proceeding upstream	Common general pattern in harbour and river systems	Not a universal substitute for the chart at every channel or junction
Vessel heading or tidal stream	Describes the boat or water at that moment	Does not define the buoyage direction
Observed buoy sequence	Useful corroboration of the charted arrangement	One mark may be misidentified, displaced or temporarily altered

Resolve a junction before reading the colours

The planned harbour entrance divides into two channels. The boat is turning across the fairway and the tidal stream is setting outward, so neither heading nor tide describes the conventional direction reliably.

1. Read the chart
Find the locally charted direction and the planned branch before assigning port or starboard meaning.
2. Identify the mark
Use predominant colour, contrasting band, shape and light to decide whether it is a preferred-channel lateral mark.
3. Translate the name
Relate the preferred channel to the mark in the established direction of buoyage.
4. Check suitability
Confirm depth, traffic, restrictions and the vessel's planned route; ‘preferred’ is not a universal clearance promise.

Sense check: If changing the boat's heading or the tide would appear to rename the marks, the reference direction has been confused with the boat's movement.

Common mistake or limitation

Assuming ‘towards the harbour’ resolves every local channel and junction without checking the chart.
Using the vessel's current heading, the tidal stream or compass north as the buoyage direction.
Treating a preferred channel as proof that the branch is safe for every vessel and condition.

Recap

Lateral side names are defined in one established conventional direction.
The boat can travel any heading without changing a mark's identity.
At bends and junctions, authoritative local information resolves ambiguity.

Optional quick check

Section 4 of 7

Your heading is west and the stream sets east in an unfamiliar junction. What should establish the direction of buoyage?

Previous Continue

Lesson 5 of 7

Translate Inbound And Outbound Views

What you will learn

Predict how fixed lateral marks appear from the cockpit on reciprocal inbound and outbound tracks without renaming the marks.

The mark identity is fixed by the conventional direction. On a simple straight reciprocal channel, turning the vessel around swaps which side of the cockpit each fixed mark appears on; it does not swap the mark's name.

In a straight Region A entrance followed in the conventional direction, the red port-hand mark bounds the port side and the green starboard-hand mark bounds the starboard side. If the boat later follows the exact reciprocal track outward, the same red port-hand mark is normally seen on the boat's starboard side and the same green starboard-hand mark on its port side.

Region B follows the same viewpoint logic with its regional colours. Inward, green port-hand lies to port and red starboard-hand lies to starboard. On the exact reciprocal outward track, the fixed green port-hand mark appears to starboard and the red starboard-hand mark appears to port.

This is a geometry aid, not an instruction to make every outbound passage a mirror image. Bends, junctions, crossing traffic, one-way directions, preferred channels, off-station aids and the actual safe-water geometry can defeat a cockpit-side mnemonic. Navigate the charted channel and circumstances, not a slogan.

Translate Inbound And Outbound Views
Simple straight case	Boat's port side	Boat's starboard side
Region A, conventional direction	Red port-hand	Green starboard-hand
Region A, exact reciprocal	Green starboard-hand	Red port-hand
Region B, conventional direction	Green port-hand	Red starboard-hand
Region B, exact reciprocal	Red starboard-hand	Green port-hand

Brief an outward transit without renaming the buoys

After entering a straight Region A channel between a red port-hand mark and a green starboard-hand mark, the boat turns and later leaves along the exact reciprocal track.

1. Keep the identities
The red mark remains the charted port-hand mark and the green mark remains the charted starboard-hand mark.
2. Reverse the viewpoint
On the simple reciprocal outward track, expect the red port-hand mark to appear to starboard and the green starboard-hand mark to port.
3. Check the real route
Use the chart, observed sequence, depth and traffic to confirm that the geometry really is the simple reciprocal case.

Sense check: If the briefing calls the red mark ‘starboard-hand’ merely because it appears on the boat's starboard side outbound, fixed mark identity and cockpit viewpoint have been confused.

Common mistake or limitation

Renaming a fixed port-hand mark when it appears on the boat's starboard side outbound.
Applying the simple reciprocal pattern through a bend or junction without checking the chart.
Using cockpit side alone when traffic, depth or a displaced aid contradicts the expected picture.

Recap

Outbound travel changes where marks appear from the helm, not what the marks are called.
Both regions share this viewpoint principle despite different lateral colours.
Abandon the mirror-image shortcut when the actual channel or conditions do not match it.

Optional quick check

Section 5 of 7

On the exact reciprocal outbound track in a straight Region A channel, where would the charted red port-hand mark normally appear relative to the boat?

Previous Continue

Lesson 6 of 7

A Safe Recognition Routine

What you will learn

Use a repeatable family-to-action routine that resists weak colour impressions and memory shortcuts.

Reliable recognition is an evidence chain: family, multiple cues, charted context and a vessel-specific action. Each stage can expose a mismatch before it becomes a steering error.

Begin with family rather than a memorised action. Ask whether the pattern is lateral, cardinal, isolated danger, safe water, special or emergency wreck. Only a lateral candidate triggers the region-and-direction translation. A cardinal candidate instead uses its black-and-yellow pattern, paired cone topmarks and white-light rhythm to name a compass side of safe water.

Then corroborate the identity. Daylight shape and topmark can remain readable when paint is faded, while a distinctive light character can support the identification at night. The expected charted position and the order of neighbouring marks test whether those observed cues form the scene you planned for.

Finish with the action, not just the name. A north cardinal indicates safe water to the north of the mark, but the navigator must still check the charted danger, position, depth, traffic and whether the northern route is usable for this vessel. Recognition informs pilotage; it does not replace it.

A Safe Recognition Routine
Stage	Question	Example evidence
1. Family	What kind of navigation problem does this mark address?	Colour pattern, shape and topmark arrangement
2. Rule	Which family-specific rule applies?	Region and direction for lateral; compass side for cardinal
3. Corroborate	Do independent cues and the chart agree?	Light rhythm, position, depth and neighbouring sequence
4. Act	What safe action suits this vessel now?	Route, clearance, traffic, speed, sea room and alternative

Recognise a faded mark without guessing

In flat evening light, a buoy's paint looks dull and its colour is uncertain. A can-like outline, topmark and charted sequence remain visible.

1. Hold a safe state
Maintain adequate distance and speed while the identification is uncertain.
2. Build the family case
Compare shape, topmark and any light character with the candidate families rather than forcing a colour guess.
3. Match the scene
Check charted position, neighbouring aids, depth trend and the expected direction or danger.
4. Act on agreement
Use the mark only when the evidence is coherent; otherwise retain sea room and move to the safe alternative.

Sense check: If one weak colour impression overrules shape, sequence, chart and depth, the evidence chain is upside down.

Common mistake or limitation

Choosing an action from colour before identifying the family.
Treating two dependent observations—such as two displays using one position source—as independent confirmation.
Stopping at the correct mark name without checking whether the indicated route is usable.

Recap

The routine is family → rule → corroborate → act.
Multiple agreeing cues are stronger than a single vivid detail.
The charted situation and vessel constraints complete the decision.

Optional quick check

Section 6 of 7

A black-over-yellow mark with both cone topmarks pointing up is charted beside a danger. What completes the recognition?

Previous Continue

Lesson 7 of 7

When The Mark Does Not Fit

What you will learn

Respond conservatively when an aid is missing, displaced, damaged or inconsistent with the charted navigation picture.

An aid to navigation supports a position and route decision; it is not guaranteed to be exactly on station or operating correctly. Protect the vessel first, then diagnose the mismatch from independent evidence.

The Canadian Coast Guard warns that aids may fail, be out of position or altered without immediate notice, and that charted buoy positions are approximate. The operational lesson applies more widely: never make a close-quarters route depend on one floating aid being exactly where or how you expect.

When the observed mark does not fit the planned picture, reduce the rate at which risk is developing. Slow, stop, hold, turn away or move to known safe water as the vessel and traffic allow. Preserve lookout and control before spending attention on a chart, display or publication search.

Cross-check an independently established position, depth and trend, charted hazards, the sequence of other aids, visual or radar cues, and current notices or warnings. If the discrepancy remains unexplained, do not chase the buoy or squeeze past its assumed side. Use the safe alternative and report the defect to the responsible authority once immediate navigation is under control.

When The Mark Does Not Fit
Mismatch	Immediate priority	Useful cross-check
Expected buoy is missing	Keep clear of the charted danger or channel edge	Position, depth, neighbouring sequence and current notices
Buoy appears off station	Do not use it as an exact boundary or steer close to inspect	Independent fix, bearings/ranges, chart and observed water
Colour, topmark or light is damaged	Avoid acting on the uncertain cue alone	Remaining shape, rhythm, sequence and position evidence
Chart, depth and mark disagree	Create time and sea room before diagnosis	Alternative position methods and a known safe route

Handle a missing mark and an early depth change

A planned lateral buoy is not visible and the depth starts reducing earlier than the pilotage notes predicted. Traffic prevents an impulsive turn across the channel.

1. Control the exposure
Use an appropriate safe speed and manoeuvre that preserves traffic separation, sea room and known water.
2. Re-establish the picture
Check position independently, compare depth trend and charted contours, and identify the neighbouring aid sequence.
3. Check currency
Review applicable warnings and notices when workload permits; do not assume a missing buoy proves the charted channel has moved.
4. Use the alternative
If the mismatch is unresolved, hold, divert or return by the pre-briefed safe option rather than continuing into shrinking margin.

Sense check: A response that accelerates towards the expected buoy position to identify it has reduced both time and sea room while the evidence is least reliable.

Common mistake or limitation

Assuming a floating buoy is an exact surveyed boundary and passing unnecessarily close.
Continuing the planned track while trying to explain a growing chart, depth or mark mismatch.
Reporting or troubleshooting before maintaining lookout and placing the vessel in a safe state.

Recap

Treat buoy positions and operation as aids, not guarantees.
Protect the vessel before directing attention to the cause of a mismatch.
Do not chase or pass close to an uncertain mark; report defects after the situation is safe.

Optional quick check

Section 7 of 7

An expected lateral buoy is missing and the depth is reducing earlier than planned. What is the best immediate approach?

Previous Continue to Practise

Lesson previewWhat IALA Buoyage Is Trying To Tell You1 section shown

Preview lesson

What IALA Buoyage Is Trying To Tell You

What you will learn

Separate the main buoyage families and decide what evidence is still needed before a mark becomes a safe pilotage instruction.

Lateral-system comparison

Keep the side and shape; translate the colour

Conventional direction of buoyage

Region A

New Zealand, United Kingdom and much of Europe

Port-hand

Red · can / cylindrical

Starboard-hand

Green · cone / conical

Region B

Canada and the United States

Port-hand

Green · can / cylindrical

Starboard-hand

Red · cone / conical

Region A/B reverses lateral red and green. Port-hand still means the port side in the conventional direction and uses the can shape; starboard-hand still uses the cone shape.

The lateral colours change between regions; the port and starboard jobs and the can and cone shape language do not.

What IALA Buoyage Is Trying To Tell You
Mark family	Question it answers	Still check
Lateral / preferred channel	Which side or branch is defined in the direction of buoyage?	Region, direction, charted channel and vessel suitability
Cardinal	On which named compass side does safe water lie?	Danger extent, position and a usable route
Isolated danger / safe water	Is there a local danger or navigable water around the mark?	Charted feature, depth and surrounding hazards
Special / emergency wreck	Is a special-purpose area or newly marked wreck being indicated?	Chart symbol, notes, notices and local directions

Turn colours into a checked pilotage picture

Approaching unfamiliar water, the crew reports a red mark, a green mark, a yellow mark and a black-and-yellow mark ahead. The colours alone do not define one safe route.

1. Classify the family
Use shape, topmark, colour pattern and light if visible to distinguish lateral, special and cardinal candidates.
2. Locate the marks
Compare their observed order and relative positions with the current chart and the expected channel or danger.
3. Apply the right rule
Use region and direction only for lateral meaning; use the named safe-water side for a cardinal mark and the charted purpose for a special mark.
4. Retain margin
Choose an action suitable for the boat, depth, traffic and conditions, without passing unnecessarily close to a buoy.

Sense check: If the decision rests on one colour or one remembered phrase, the family and charted context have not yet been established.

Common mistake or limitation

Treating every buoy as a lateral mark that dictates a side of the channel.
Naming a mark from colour alone while ignoring shape, topmark, light and sequence.
Steering close to a buoy as though its position were an exact surveyed boundary.

Recap

Different mark families answer different navigation questions.
A reliable identification uses several agreeing cues, not colour alone.
The safe action still depends on charted context, the vessel and current conditions.

Optional quick check

Section 1 of 1

A yellow buoy is sighted near the planned route. What is the best first response?

Continue to Practise

Lesson routeWhat IALA Buoyage Is Trying To Tell You0/7 read

Lesson 1 of 7

What IALA Buoyage Is Trying To Tell You

What you will learn

Separate the main buoyage families and decide what evidence is still needed before a mark becomes a safe pilotage instruction.

Lateral-system comparison

Keep the side and shape; translate the colour

Conventional direction of buoyage

Region A

New Zealand, United Kingdom and much of Europe

Port-hand

Red · can / cylindrical

Starboard-hand

Green · cone / conical

Region B

Canada and the United States

Port-hand

Green · can / cylindrical

Starboard-hand

Red · cone / conical

Region A/B reverses lateral red and green. Port-hand still means the port side in the conventional direction and uses the can shape; starboard-hand still uses the cone shape.

The lateral colours change between regions; the port and starboard jobs and the can and cone shape language do not.

What IALA Buoyage Is Trying To Tell You
Mark family	Question it answers	Still check
Lateral / preferred channel	Which side or branch is defined in the direction of buoyage?	Region, direction, charted channel and vessel suitability
Cardinal	On which named compass side does safe water lie?	Danger extent, position and a usable route
Isolated danger / safe water	Is there a local danger or navigable water around the mark?	Charted feature, depth and surrounding hazards
Special / emergency wreck	Is a special-purpose area or newly marked wreck being indicated?	Chart symbol, notes, notices and local directions

Turn colours into a checked pilotage picture

Approaching unfamiliar water, the crew reports a red mark, a green mark, a yellow mark and a black-and-yellow mark ahead. The colours alone do not define one safe route.

1. Classify the family
Use shape, topmark, colour pattern and light if visible to distinguish lateral, special and cardinal candidates.
2. Locate the marks
Compare their observed order and relative positions with the current chart and the expected channel or danger.
3. Apply the right rule
Use region and direction only for lateral meaning; use the named safe-water side for a cardinal mark and the charted purpose for a special mark.
4. Retain margin
Choose an action suitable for the boat, depth, traffic and conditions, without passing unnecessarily close to a buoy.

Sense check: If the decision rests on one colour or one remembered phrase, the family and charted context have not yet been established.

Common mistake or limitation

Treating every buoy as a lateral mark that dictates a side of the channel.
Naming a mark from colour alone while ignoring shape, topmark, light and sequence.
Steering close to a buoy as though its position were an exact surveyed boundary.

Recap

Different mark families answer different navigation questions.
A reliable identification uses several agreeing cues, not colour alone.
The safe action still depends on charted context, the vessel and current conditions.

Optional quick check

Section 1 of 7

A yellow buoy is sighted near the planned route. What is the best first response?

Continue

Lesson 2 of 7

What Changes Between Region A And Region B

What you will learn

State exactly which parts of the lateral system change between IALA Regions A and B and which recognition rules remain common.

The A/B distinction changes the red-and-green colour meaning of lateral marks. It does not invert the whole buoyage system or change the port-can and starboard-cone shape convention.

What Changes Between Region A And Region B
Feature	Region A	Region B
Port-hand lateral colour	Red	Green
Starboard-hand lateral colour	Green	Red
Port-hand shape	Can / cylindrical	Can / cylindrical
Starboard-hand shape	Cone / conical	Cone / conical
Non-lateral families	Common IALA family logic	Common IALA family logic

Separate the variable from the constant

A skipper used to Region A prepares for a passage in Region B and is tempted to relearn every buoy family from scratch.

1. Isolate the change
Reverse the red-and-green lateral colour assignments, including the predominant colour of preferred-channel marks.
2. Keep the stable cues
Retain port-can and starboard-cone shape meaning and the established patterns of non-lateral families.
3. Verify locally
Use the current chart and national publications for the direction, numbering, alterations and local application.

Sense check: If the plan reverses cardinal colours or swaps can and cone shapes, it has extended the regional difference too far.

Common mistake or limitation

Saying that every buoy colour and family reverses between the two regions.
Forgetting that a preferred-channel mark is part of the lateral system.
Swapping the can and cone shapes as well as the red and green colours.

Recap

Region changes colour assignment, not the port and starboard jobs.
Use shape as an independent cue: port can, starboard cone.
Current national charts and publications still control the local application.

Optional quick check

Section 2 of 7

Which feature remains the same when moving from Region A to Region B?

Previous Continue

Lesson 3 of 7

Region A And Region B

What you will learn

Translate a lateral mark correctly after identifying whether the passage is in Region A or Region B.

Region is the first lateral-system context check. The United Kingdom uses Region A; Canada and the United States use Region B. The same side names are expressed with opposite red and green colours.

Region A And Region B
Region example	Port-hand lateral	Starboard-hand lateral	Translation
A — United Kingdom	Red; can/cylindrical	Green; cone/conical	Region A → direction → port red / starboard green
B — Canada	Green; can/cylindrical	Red; cone/conical	Region B → direction → port green / starboard red

Re-brief the crew before entering unfamiliar waters

A crew trained in the United Kingdom is approaching a Canadian harbour. One person remembers only that red marks were port-hand during UK exercises.

1. Name the region
Confirm from the current chart and national information that the passage uses Region B.
2. Name the direction
Establish the charted conventional direction before assigning a side to any lateral mark.
3. Translate the side
In Region B, port-hand is green and can-shaped; starboard-hand is red and conical where shape is used.
4. Check the scene
Confirm the observed sequence, charted channel, depth and traffic before choosing the route.

Sense check: A colour remembered from another country is not a side instruction until the region and direction have been established.

Common mistake or limitation

Applying a Region B returning mnemonic in Region A waters.
Remembering red or green without first naming the region and direction.
Assuming the opposite colours mean that port and starboard themselves have changed.

Recap

Region A and Region B reverse lateral red and green.
The side names and can/cone shape meanings remain stable.
A safe memory sequence is region → direction → side → colour → action.

Optional quick check

Section 3 of 7

In the conventional direction of buoyage in Canadian Region B, which combination identifies the starboard-hand lateral mark?

Previous Continue

Lesson 4 of 7

Direction Of Buoyage

What you will learn

Establish the conventional direction of buoyage from authoritative navigation information before interpreting a lateral mark.

Direction Of Buoyage
Candidate cue	Use	Limit
Current chart / authority publication	Primary source for the local conventional direction and alterations	Must be the applicable, current information
Approaching from seaward or proceeding upstream	Common general pattern in harbour and river systems	Not a universal substitute for the chart at every channel or junction
Vessel heading or tidal stream	Describes the boat or water at that moment	Does not define the buoyage direction
Observed buoy sequence	Useful corroboration of the charted arrangement	One mark may be misidentified, displaced or temporarily altered

Resolve a junction before reading the colours

1. Read the chart
Find the locally charted direction and the planned branch before assigning port or starboard meaning.
2. Identify the mark
Use predominant colour, contrasting band, shape and light to decide whether it is a preferred-channel lateral mark.
3. Translate the name
Relate the preferred channel to the mark in the established direction of buoyage.
4. Check suitability
Confirm depth, traffic, restrictions and the vessel's planned route; ‘preferred’ is not a universal clearance promise.

Sense check: If changing the boat's heading or the tide would appear to rename the marks, the reference direction has been confused with the boat's movement.

Common mistake or limitation

Assuming ‘towards the harbour’ resolves every local channel and junction without checking the chart.
Using the vessel's current heading, the tidal stream or compass north as the buoyage direction.
Treating a preferred channel as proof that the branch is safe for every vessel and condition.

Recap

Lateral side names are defined in one established conventional direction.
The boat can travel any heading without changing a mark's identity.
At bends and junctions, authoritative local information resolves ambiguity.

Optional quick check

Section 4 of 7

Your heading is west and the stream sets east in an unfamiliar junction. What should establish the direction of buoyage?

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Lesson 5 of 7

Translate Inbound And Outbound Views

What you will learn

Predict how fixed lateral marks appear from the cockpit on reciprocal inbound and outbound tracks without renaming the marks.

Translate Inbound And Outbound Views
Simple straight case	Boat's port side	Boat's starboard side
Region A, conventional direction	Red port-hand	Green starboard-hand
Region A, exact reciprocal	Green starboard-hand	Red port-hand
Region B, conventional direction	Green port-hand	Red starboard-hand
Region B, exact reciprocal	Red starboard-hand	Green port-hand

Brief an outward transit without renaming the buoys

After entering a straight Region A channel between a red port-hand mark and a green starboard-hand mark, the boat turns and later leaves along the exact reciprocal track.

1. Keep the identities
The red mark remains the charted port-hand mark and the green mark remains the charted starboard-hand mark.
2. Reverse the viewpoint
On the simple reciprocal outward track, expect the red port-hand mark to appear to starboard and the green starboard-hand mark to port.
3. Check the real route
Use the chart, observed sequence, depth and traffic to confirm that the geometry really is the simple reciprocal case.

Sense check: If the briefing calls the red mark ‘starboard-hand’ merely because it appears on the boat's starboard side outbound, fixed mark identity and cockpit viewpoint have been confused.

Common mistake or limitation

Renaming a fixed port-hand mark when it appears on the boat's starboard side outbound.
Applying the simple reciprocal pattern through a bend or junction without checking the chart.
Using cockpit side alone when traffic, depth or a displaced aid contradicts the expected picture.

Recap

Outbound travel changes where marks appear from the helm, not what the marks are called.
Both regions share this viewpoint principle despite different lateral colours.
Abandon the mirror-image shortcut when the actual channel or conditions do not match it.

Optional quick check

Section 5 of 7

On the exact reciprocal outbound track in a straight Region A channel, where would the charted red port-hand mark normally appear relative to the boat?

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Lesson 6 of 7

A Safe Recognition Routine

What you will learn

Use a repeatable family-to-action routine that resists weak colour impressions and memory shortcuts.

Reliable recognition is an evidence chain: family, multiple cues, charted context and a vessel-specific action. Each stage can expose a mismatch before it becomes a steering error.

A Safe Recognition Routine
Stage	Question	Example evidence
1. Family	What kind of navigation problem does this mark address?	Colour pattern, shape and topmark arrangement
2. Rule	Which family-specific rule applies?	Region and direction for lateral; compass side for cardinal
3. Corroborate	Do independent cues and the chart agree?	Light rhythm, position, depth and neighbouring sequence
4. Act	What safe action suits this vessel now?	Route, clearance, traffic, speed, sea room and alternative

Recognise a faded mark without guessing

In flat evening light, a buoy's paint looks dull and its colour is uncertain. A can-like outline, topmark and charted sequence remain visible.

1. Hold a safe state
Maintain adequate distance and speed while the identification is uncertain.
2. Build the family case
Compare shape, topmark and any light character with the candidate families rather than forcing a colour guess.
3. Match the scene
Check charted position, neighbouring aids, depth trend and the expected direction or danger.
4. Act on agreement
Use the mark only when the evidence is coherent; otherwise retain sea room and move to the safe alternative.

Sense check: If one weak colour impression overrules shape, sequence, chart and depth, the evidence chain is upside down.

Common mistake or limitation

Choosing an action from colour before identifying the family.
Treating two dependent observations—such as two displays using one position source—as independent confirmation.
Stopping at the correct mark name without checking whether the indicated route is usable.

Recap

The routine is family → rule → corroborate → act.
Multiple agreeing cues are stronger than a single vivid detail.
The charted situation and vessel constraints complete the decision.

Optional quick check

Section 6 of 7

A black-over-yellow mark with both cone topmarks pointing up is charted beside a danger. What completes the recognition?

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Lesson 7 of 7

When The Mark Does Not Fit

What you will learn

Respond conservatively when an aid is missing, displaced, damaged or inconsistent with the charted navigation picture.

When The Mark Does Not Fit
Mismatch	Immediate priority	Useful cross-check
Expected buoy is missing	Keep clear of the charted danger or channel edge	Position, depth, neighbouring sequence and current notices
Buoy appears off station	Do not use it as an exact boundary or steer close to inspect	Independent fix, bearings/ranges, chart and observed water
Colour, topmark or light is damaged	Avoid acting on the uncertain cue alone	Remaining shape, rhythm, sequence and position evidence
Chart, depth and mark disagree	Create time and sea room before diagnosis	Alternative position methods and a known safe route

Handle a missing mark and an early depth change

A planned lateral buoy is not visible and the depth starts reducing earlier than the pilotage notes predicted. Traffic prevents an impulsive turn across the channel.

1. Control the exposure
Use an appropriate safe speed and manoeuvre that preserves traffic separation, sea room and known water.
2. Re-establish the picture
Check position independently, compare depth trend and charted contours, and identify the neighbouring aid sequence.
3. Check currency
Review applicable warnings and notices when workload permits; do not assume a missing buoy proves the charted channel has moved.
4. Use the alternative
If the mismatch is unresolved, hold, divert or return by the pre-briefed safe option rather than continuing into shrinking margin.

Sense check: A response that accelerates towards the expected buoy position to identify it has reduced both time and sea room while the evidence is least reliable.

Common mistake or limitation

Assuming a floating buoy is an exact surveyed boundary and passing unnecessarily close.
Continuing the planned track while trying to explain a growing chart, depth or mark mismatch.
Reporting or troubleshooting before maintaining lookout and placing the vessel in a safe state.

Recap

Treat buoy positions and operation as aids, not guarantees.
Protect the vessel before directing attention to the cause of a mismatch.
Do not chase or pass close to an uncertain mark; report defects after the situation is safe.

Optional quick check

Section 7 of 7

An expected lateral buoy is missing and the depth is reducing earlier than planned. What is the best immediate approach?

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