Nautical Warning Signals

Nautical warning signals are the common language system between shipping, harbour authorities, coastal radio and race management. For sailors, they are not merely formal knowledge from the SkS or SSS course, but a direct decision-making aid on the water: When may a start take place? When must the race be abandoned? When is an area closed to all boats? Those who can reliably interpret flags, sound signals and official weather warnings react earlier than the competition – and protect crew and equipment before the situation becomes critical.

In regatta sailing, three signal worlds overlap: the International Regulations for Preventing Collisions at Sea (COLREGS), meteorological warning systems (storm flags, DWD warnings, sea weather reports) and regatta-specific signals from the race officer (Regatta Committee, PRO). This guide organises all three levels for practical use at regatta level.

Why nautical warning signals are decisive for regatta sailors

Regatta sailing rarely takes place in completely isolated waters. On the Kiel Fjord, Lake Constance, the Solent or in Mediterranean harbours near sailing areas, sports boats, ferries, cargo vessels and authority craft share the same water. Warning signals apply to everyone – regardless of whether a medal race or a club handicap race is in progress.

The three levels at a glance

1. Navigation law signals (COLREGS): Always apply, even during a regatta. Fog signals, night signals and signals of vessels not under command must be known by every crew.
2. Meteorological warning signals: Storm flags on lighthouses and harbour installations, DWD warning levels, sea weather reports via coastal radio and NAVTEX – they indicate weather-related hazards, not race status.
3. Regatta signals (RRS): AP flag, N flag (abandonment), postponement – they control the race schedule and are binding only for participating boats, unless the Sailing Instructions provide otherwise.

Each higher level may impose additional restrictions, but can never override COLREGS.

Storm flags and meteorological warning signals

The international storm warning system (WMO/IHO) has used two standardised signal flags for decades, hoisted on lighthouses, pilot stations and harbour installations. On the water they are visible from great distance – important when the smartphone has no network.

The two storm flags in detail

In German coastal waters, official storm warnings from the DWD (levels 1–4) supplement the visual system. For regatta teams: anyone who sees a storm warning flag at the pontoon in the morning or receives a level 3 severe weather warning via app must interpret the PRO's morning briefing differently than with a green weather window.

Sound signals in fog and restricted visibility

COLREGS (Rule 35) define mandatory signals in fog, snowfall or other visibility impairments. For regatta sailors they are doubly relevant: first for collision avoidance in dense fleet racing, second as an indicator that the Race Committee must abandon or postpone a round.

Mandatory signals by vessel type

With visibility under 500 metres, additional speed and distance restrictions apply. Regatta PROs often set the N flag (abandonment) or postpone the start in such conditions – the link between COLREGS obligation and regatta decision is direct here.

Distress and danger signals on the water

In addition to weather warnings, internationally standardised distress signals exist that every regatta sailor must recognise – both for sending in their own emergency and for correctly responding to other boats.

Visual and acoustic distress signals

• Red star rocket or red hand flare: Vessel in distress – organise help immediately, DSC distress call, inform SAR
• SOS in Morse code (... --- ...): Visually with mirror or light, acoustically with horn – counts as distress signal
• Flag NC (blue and white checkered): Boat requesting medical assistance
• Continuous sound with fog horn: Alarm signal when close to ground or collision
• Orange smoke signal: Signal for rescue services and search aircraft during MOB search

Pyrotechnics and modern alternatives

1. Hand flares and parachute rockets: Only ignite in genuine emergency; false use triggers costly SAR operations and may have criminal consequences.
2. EPIRB and AIS-SART: Automatically transmit position data – standard on offshore regattas, increasingly also on coastal races.
3. DSC distress call on VHF channel 16: Brief and precise: emergency, position, number of persons, type of emergency.

Regatta signals vs. nautical warning signals

Many sailors confuse the AP flag (postponement, race delayed) with a storm warning – or ignore storm flags because the committee boat has not yet set an N signal. The distinction is safety-critical.

Comparison: Who sends what?

The N flag (depiction: blue and white checkered, 4:5) in the regatta context means: all boats must immediately stop racing and may return to the starting point. It is set when weather no longer permits safe sailing in the area – regardless of whether the DWD has already issued an official warning.

VHF, coastal radio and digital warning sources

Modern regatta teams combine classic signals with digital sources. On German coasts, coastal radio (e.g. Norddeich Radio, Bremen Radio) provides sea weather reports and storm warnings at fixed broadcast times. NAVTEX receivers on board automatically print warnings for the navigated sea area.

Important information sources at a glance

1. VHF channel 16: Distress and calling frequency; weather information often on channel 68 or 69 (area-dependent)
2. DWD sea weather reports and warning maps: Check via app before regatta day and at the pontoon in the morning
3. Meteoalarm.eu: Colour-coded warnings for European regatta areas
4. GRIB files and routing software: Supplement but do not replace official storm flags
5. Regatta radio (organiser radio): Separate frequency for PRO instructions – do not confuse with distress call

The smaller the area, the shorter the reaction time after a storm warning.

Practice: warning signals in everyday regatta life

Morning briefing: checklist for skipper and tactician

• DWD warnings and Meteoalarm checked for area and surroundings
• Storm flags on lighthouses and harbour entrance read
• Sea weather report or inland lake forecast discussed with crew
• Sailing Instructions: wind limits, abandonment rules, return point known
• Fog horn, life jackets and DSC radio functional
• PRO radio frequency and distress channel 16 stored in radio
• Alternative: training sail instead of race agreed in marginal weather

During the race: priority order

1. COLREGS and distress signals always take precedence over tactics and laylines.
2. Storm flags and DWD warnings require skipper decision – even without RC signal.
3. Regatta signals from the PRO are binding for scoring and fleet behaviour.
4. In case of thunderstorm immediate withdrawal; details on lightning risk in the linked thunderstorm article.

After the signal: crew communication

When the Race Committee signals postponement or abandonment, clear communication on board applies:

• Helmsman confirms signal visually (flag on committee boat or radio)
• Tactician informs about Scoring on Abandonment (will the race be scored?)
• Crew secures sails and rigging for the return
• In fog: continue sounding fog signals until berth is reached

Warning signal response on board

• Signal recognised and confirmed
• Crew informed
• Sails reduced
• Course to safe waters
• Fog horn ready
• Radio on channel 16
• PRO contacted if necessary
• Berth safely reached

Warning signals in various regatta formats

Inshore and Olympic classes

On windward-leeward courses near the harbour, the Race Committee often reacts quickly to visible thunderstorm cells. Dinghy crews must know fog signals, because in rain and spray fog visibility of marks and other boats drops sharply. The close link to heavy weather technique and depower manoeuvres becomes immediately relevant with storm warnings.

Coastal and offshore regattas

Here storm flags and sea weather reports are often the only early warning before GRIB data is updated. Crews on ORC offshore races check NAVTEX and coastal radio at every watch change. Routing decisions with storm warning 1 must be coordinated with offshore strategy and weather windows.

Inland lake regattas

On lakes, lighthouse storm flags are often absent; instead, convective thunderstorms and cold-front gusts are possible within minutes. Local effects such as thermal winds and coastal breeze are covered in depth in the article on cloud formation and local effects.

Common mistakes and how to avoid them

1. Waiting only for PRO signals: Storm flags and DWD warnings apply independently of the Race Committee.
2. Forgetting fog signals: With regatta focus many crews sail without mandatory signals – collision risk and insurance consequences.
3. Confusing radio channels: Organiser radio is not channel 16; distress calls belong exclusively on 16.
4. Pyrotechnics in non-emergency: Test training rockets on land, never on the water without emergency.
5. Not training signals as a team: Before the season, practise fog and storm scenarios in club training.

Frequently asked questions (FAQ)

Do storm flags also apply to inland lakes?

No, observe DWD warnings and local area rules there.

Must I go afloat immediately when the AP flag is displayed?

No, AP means postponement; wait for PRO instructions.

Who may set the N flag?

Only the Race Committee, not individual boats.

Is GRIB sufficient instead of storm flag?

No, official signals take precedence.

What to do in thunderstorm during the race?

Abandon immediately and head for the safest area.

Related topics

• Thunderstorms and storm warnings
• Fog and restricted visibility
• Abandonment and postponement
• AP, postponement and abandonment
• Meteorology for sailors

Last updated: 4 July 2026