Why signs and signals matter

CEVNI (the European code for inland waterways) uses a standard set of signs, buoys and lights so that skippers from any country can navigate the same rules. For the ICC test you need to recognise the shapes, colours and what each one means for your boat.

Shapes and colours

Waterway signs use simple geometric shapes to give an instant meaning:

• A red ring or red disc on a panel means prohibition (a 'no' sign) - for example a red disc with a horizontal white bar bans overtaking.
• A red diagonal cross on white means a total stop or a channel closed to navigation.
• A blue disc or square means a mandatory instruction, such as 'keep to this side' or 'sound your horn'.
• Blue and white together giving recommendations, not orders.
• A black shape on white (arrow, diamond, cross) usually gives information, such as which side to pass a bridge pier or where the channel narrows.

Key sign categories

• Prohibition signs: no entry, no overtaking, no mooring, no anchoring, no wash, no waiting.
• Mandatory signs: minimum speed, direction to follow, sound signal required, radio watch required.
• Restrictive signs: reduced clearance height or width ahead.
• Recommendation signs: preferred side of channel, recommended speed.
• Other signs: end of a restriction, general warning, information panels (harbour, fuel, mooring).

Buoyage - lateral marks

Inland lateral buoyage differs from IALA sea buoyage in one big way: it follows the direction of the main current (usually downstream), not a fixed compass rule.

• Red conical or pointed-top buoys mark the right-hand edge of the channel going downstream.
• Green cylindrical or flat-top buoys mark the left-hand edge going downstream.
• When heading upstream you simply keep the marks on the opposite sides to what they show downstream.

Lights at night

• Green light = leave to starboard (going downstream), matching the green buoy convention.
• Red light = leave to port.
• Yellow/amber lights are often used on ferries and for special warnings.
• Isolated danger and channel-narrowing marks may show quick-flashing or occulting lights - learn to tell flashing rate apart from steady lights.

Sound signals

One long blast means 'attention' or warning of a manoeuvre; a series of short blasts can mean danger or request to pass. Bridges and locks often require a specific signal (for example, three short blasts asking a lock to open) - always check local sign panels as they can override the general rule.

Common mistakes

• Mixing up sea IALA buoyage with inland CEVNI buoyage - colours can mean different sides.
• Forgetting that inland lateral marks follow the current direction, not north/south.
• Ignoring blue 'recommended' signs as if they were optional decoration - they carry real safety meaning.
• Not checking for a supplementary panel under a main sign (it changes or limits the main sign's meaning, e.g. distance or time it applies).

Why sound and light signals matter

CEVNI signals let vessels communicate intentions and warn of danger when radio or eye contact isn't enough. You must know the exact blast patterns, light colours and their meanings cold - the exam tests precise recall, not general sense.

Sound signal basics

• A short blast lasts about 1 second; a long (prolonged) blast lasts about 4 seconds.
• One short blast = 'I am altering course to starboard'.
• Two short blasts = 'I am altering course to port'.
• Three short blasts = 'My engines are going astern' (operating astern propulsion).
• Four short blasts = 'I am unable to manoeuvre' (used at bends or when leaving a berth, warning others).
• One long blast = a general warning, e.g. approaching a blind bend, junction, or leaving a mooring where visibility is restricted.
• Series of very short blasts (at least 6, each about 1 second) = danger signal, meaning 'I am in doubt that you are taking sufficient action to avoid collision' or general alarm.
• Sound signals must be repeated if the manoeuvre continues or if there's no response.

Light signals

• Light signals mirror sound signals so they can be used together or when sound could be missed (e.g. noisy engine rooms, night-time).
• One flash of white light = altering course to starboard (mirrors one short blast).
• Two flashes = altering course to port.
• Three flashes = engines going astern.
• A single long flash (about 4 seconds) = the general warning light, same use as one long blast.
• Flashing light signals are especially important at night and on radar-only stretches where sound may not carry over engine noise or wind.

Blue board and blue flashing light

• Large vessels navigating 'on the wrong side' (starboard-to-starboard passing, common on bends) show a rectangular blue board or blue flashing light to signal this intention - not a general danger signal.
• This is different from the amber/yellow flashing light used by vessels underway that must not be overtaken, or that have priority.

Common mistakes to avoid

• Confusing short (1 sec) and long/prolonged (4 sec) blasts - the duration carries the meaning, not just the count.
• Mixing up port and starboard blast counts (remember: one blast = starboard, like 'one' sounds sharper/shorter direction first alphabetically is NOT the trick - just learn 1=starboard, 2=port).
• Forgetting that four short blasts signals inability to manoeuvre, not danger - the danger signal is the longer series of very short blasts.
• Assuming light signals are optional extras - at night or in poor visibility they are the primary signal, not a backup.
• Forgetting the blue board/blue light is a passing intention signal, unrelated to the general warning signals.

Rules between vessels & overtaking

CEVNI (the Code Europeen des Voies de Navigation Interieure, mirrored in the RYA's ICC inland rules) sets out who gives way when inland waterway traffic meets. Unlike sea rules, these are shaped by current, channel width and commercial traffic, so the priorities are different from COLREGs.

The core hierarchy

• Small craft (including most pleasure boats) must always keep out of the way of large vessels, convoys and passenger vessels.
• Vessels proceeding downstream (with the current) generally have priority over vessels going upstream, because downstream vessels have less manoeuvrability and a longer stopping distance.
• The upstream vessel normally takes early, positive action to keep clear.
• In narrow channels or fairways, a vessel must not hamper the passage of a vessel that can only navigate safely within that channel.

Overtaking

• The overtaking vessel is always the give-way vessel and is responsible for keeping clear until fully past and clear.
• Sound signals matter: two long plus one short blast means 'I intend to overtake on your port side'; two long plus two short means 'I intend to overtake on your starboard side'.
• The vessel being overtaken should hold course and speed, but if overtaking is not possible (too narrow, or dangerous) it should signal one long, one short, one long, one short blasts to indicate it cannot allow overtaking.
• Overtaking must never take place in a lock, at a lock approach, under a bridge, in a bend with restricted visibility, or in a narrow channel where safe clearance can't be guaranteed.
• Large vessels and convoys should not be overtaken unless there is clearly enough room.

Meeting head-on

• On most rivers vessels keep to the starboard (right-hand) side of the channel and pass port-to-port, but always check local signage as some stretches reverse this or mark a preferred channel with blue boards and blue flashing lights (the 'blue board' system), which means pass starboard-to-starboard instead.
• When a vessel shows a blue board/light, an oncoming vessel must not overtake or pass on that side.

Common mistakes

• Assuming COLREGs sea rules (stand-on/give-way by aspect) apply directly — CEVNI priority is about current direction and vessel size, not just angle of approach.
• Forgetting the overtaking vessel keeps responsibility for the whole manoeuvre, not just the initial pass.
• Missing the blue board signal and passing on the wrong side.
• Trying to overtake near locks, bridges or bends — always the highest-risk exam trap.

Locks

Locks raise or lower vessels between different water levels. Before entering, check the light signals at the lock entrance - red means stop, and green (or two greens) means you may proceed in. Never enter on red, even if the gates look open.

• Approach slowly and keep clear of the sill and gates until signalled in.
• Large vessels and convoys normally have priority over small craft and pleasure boats, unless local signs state otherwise.
• Inside the chamber, moor up promptly using bow and stern lines, and fend off - do not use the engine to hold position once lines are made fast.
• Keep well clear of other vessels' propellers and the turbulence caused by water filling or emptying.
• Do not start the engine or leave your mooring until the lock-keeper or signal shows it is safe to exit.
• Small pleasure craft may be asked to share a lock with commercial vessels; follow the lock-keeper's instructions at all times.

Tunnels

Tunnels are treated as narrow, restricted-visibility passages, so special rules apply.

• A blue light or sign at the entrance usually means one-way traffic only - wait your turn.
• Switch on navigation lights before entering, even in daylight, since the interior is dark.
• Keep to the centre or as directed, maintain a slow, steady speed, and keep a sharp lookout since sound and vision are limited.
• Overtaking inside a tunnel is normally prohibited unless expressly signed as permitted.
• Some tunnels prohibit small craft entirely, or only allow them under tow or with a permit - always check local notices (bekendmakingen) before transit.

Bridges

Bridges carry their own signals and clearance rules.

• Fixed bridges show clearance height boards (in metres) - always check your air draught against the marked figure, including mast and aerials, before approaching.
• Movable (opening) bridges show light signals: red means the bridge is closed to traffic and you must stop; green means you may pass.
• Some bridges use sound signals (e.g. one long blast) to request opening - follow local regulations for the correct signal.
• Approach opening bridges slowly and be ready to hold station, since opening can take several minutes and other traffic may be waiting.
• Never pass under a bridge showing a red cross or red light, even if it appears open enough to pass.

Common mistakes

• Assuming green means go faster - always proceed at a controlled speed.
• Forgetting to check air draught boards before low bridges.
• Overtaking in tunnels or locks where it is forbidden.
• Not securing lines properly inside a lock chamber, causing the vessel to swing as water levels change.

What is the blue board?

The blue board (blue flag by day, or a clear/white flashing light by night) is a signal used on European inland waterways under CEVNI to tell other vessels you intend to pass or be passed on the 'wrong' side - that is, port to port instead of the normal starboard to starboard.

The normal rule first

Under CEVNI, vessels meeting head-on normally pass starboard to starboard (each keeps to the right, like driving on the right). The blue board is the exception that reverses this for a specific situation.

When it is used

• A vessel wanting to be overtaken or passed on its port side shows a blue board on the port side, with a clear or white scintillating (flashing) light above it at night.
• It is most common on wide rivers, canals, and lakes where the channel or current makes a port-to-port passing safer.
• It signals intent - it does not by itself give right of way. The other vessel must acknowledge, usually by also showing a blue board, before either changes course.

How the manoeuvre works

1. The vessel proposing the change shows the blue board in good time.

2. The approaching vessel confirms agreement by also displaying a blue board.

3. Only once both boards are up should either vessel alter course to pass port to port.

4. If the other vessel does not show a blue board in response, you must not assume agreement - continue on the normal starboard-to-starboard basis or take avoiding action.

Key numbers and details

• Day signal: rigid blue board (rectangular).
• Night signal: clear or white flashing (scintillating) light, shown together with or in place of the board depending on the fitting.
• Position: mounted so it is clearly visible from the approaching vessel's direction, typically forward on the side of intended passing.
• Large vessels and convoys on major rivers (e.g. the Rhine) use this signal frequently due to strong currents favouring one bank.

Common mistakes

• Assuming a blue board alone changes the rules - it only works once BOTH vessels are showing it.
• Confusing blue board passing with overtaking sound signals - they are different systems (sound signals cover overtaking on narrow channels; the blue board covers meeting/passing).
• Forgetting the night-time light must be clear/white and flashing, not a steady light.
• Not reacting if the other vessel fails to answer - silence or no board means stick to the standard rule.
• Mixing this up with lateral buoyage colours - blue board is a vessel signal, not a channel marker.

Documents you must carry

Under CEVNI (and the ICC scheme it underpins), the skipper of a vessel must carry proof of competence and, for the vessel itself, proof it is fit to be on the water.

• The International Certificate of Competence (ICC) is the personal qualification proving you can handle the class of craft and the type of water (inland or coastal/tidal endorsement).
• The vessel needs registration papers, and where required, a certificate of seaworthiness or class inspection document.
• Some countries also require third-party insurance evidence to be carried on board — always check the local waterway authority's rules before you travel, since national add-ons sit on top of the CEVNI base rules.
• Radio operator certification is needed if VHF is fitted and you intend to transmit.

General conduct principles

CEVNI's underlying philosophy is 'good seamanship' — every skipper must act to avoid danger even when no specific rule covers the situation. Key duties:

• Keep a proper lookout at all times, by sight and hearing.
• Proceed at a safe speed so you can always stop within the distance you can see to be clear.
• Avoid excessive wash that could endanger other craft, moored boats, or the bank.
• Never obstruct a fairway or a vessel that is restricted in its ability to manoeuvre.
• Give way early and obviously — small, late course changes cause confusion and are worse than doing nothing.

Priority rules (who gives way)

The general priority hierarchy on inland waterways, from highest to lowest right of way:

1. Vessels in distress / not under command.

2. Convoys and vessels restricted in manoeuvrability (e.g. large commercial barges, dredgers working).

3. Vessels proceeding with the current (downstream) usually have priority over those going against it, because they have less manoeuvring control — this is the opposite of what many candidates instinctively assume.

4. Small/pleasure craft give way to commercial vessels in almost all crossing and overtaking situations.

5. A vessel crossing must give way to a vessel proceeding along the main channel.

Common mistakes

• Assuming upstream traffic always has priority — it is usually downstream traffic that does, because stopping against the current is harder to control.
• Forgetting that sailing vessels still give way to commercial traffic on narrow fairways, despite sail generally having priority over power in open water.
• Leaving documents ashore — examiners test knowledge of what must be carried, not just displayed.
• Confusing 'right of way' with 'stand-on' — CEVNI expects the give-way vessel to act early, and the stand-on vessel to hold course and speed only as long as it remains safe to do so.

Learn the hierarchy as a list you can recite instantly — questions often present two vessels and ask which gives way.