Nevoeiro e má visibilidade na água: o que fazer

Última verificação: 14 de outubro de 2026

Passo a passo

1. Marque já a posição

   Quando vir o nevoeiro a chegar, registe de imediato a sua posição no GPS e na carta em papel.[13]

2. Abrande

   Devagar é a única velocidade segura com nevoeiro. Navegue a uma velocidade que lhe permita parar ou guinar a tempo, e mantenha o motor pronto para manobrar de imediato.[27][6]

3. Luzes acesas, refletor içado

   Acenda as luzes de navegação, mesmo de dia, e confirme que o refletor de radar está içado.[11][23][14]

4. Faça o sinal sonoro de nevoeiro

   Segundo o COLREG, um barco a motor com seguimento faz um som prolongado (4–6 segundos) pelo menos de 2 em 2 minutos; um veleiro faz um som prolongado e dois curtos. Um barco com menos de 12 m pode, em vez disso, fazer outro sinal sonoro eficaz pelo menos de 2 em 2 minutos.[1][2][3][10]

5. Olhe e escute

   Ponha mais tripulantes de vigia e confirme que todos têm colete salva-vidas vestido. Desligue a música e continue atento a motores, buzinas, vozes e sinais de nevoeiro.[8][15][18][22]

6. Use o radar e o AIS, mas não confie neles

   Use o radar e o AIS se os tiver. Lembre-se de que os barcos pequenos podem não aparecer no radar de outros navios, mesmo com refletor.[14][19][28]

7. Ouve um sinal à proa? Reduza ao mínimo

   Se ouvir à proa o sinal de nevoeiro de outro navio, reduza à velocidade mínima que lhe permita manter o rumo, e pare se for preciso, até o perigo ter passado.[7]

8. Saia das rotas de navegação

   A velocidade de segurança e com rumo constante, siga para águas menos profundas, longe das rotas de navegação movimentadas, fundeie e espere. Se tiver de atravessar uma via de tráfego, atravesse-a perpendicularmente ao sentido do tráfego.[16][9]

9. Sinal ao fundear e escuta no canal 16

   Fundeado, um navio toca o sino rapidamente durante cerca de 5 segundos pelo menos uma vez por minuto; um barco com menos de 12 m pode, em vez disso, fazer outro sinal sonoro eficaz pelo menos de 2 em 2 minutos. Continue à escuta no canal 16 de VHF.[5][3][20]

10. Peça ajuda se estiver em perigo

    Se achar que está retido num local perigoso, use o rádio VHF para pedir ajuda.[17]

O que não fazer

• Não mantenha a velocidade normal. Devagar é a única velocidade segura com nevoeiro.[27]
• Não parta do princípio de que os navios o veem no radar ou no AIS.[19][28]
• Não ligue a rádio nem se distraia com conversas; precisa dos ouvidos.[22]
• Não atravesse uma rota de navegação na diagonal; se tiver de atravessar, faça-o perpendicularmente.[9]
• Não parta do princípio de que o sol vai dissipar o nevoeiro; o nevoeiro marítimo pode durar até bem dentro da tarde.[21]

Antes de largar

• Antes de largar: instale o melhor refletor de radar que seja prático para o seu barco.[29]
• Antes de largar: leve um meio de sinalização sonora a funcionar. Os barcos com menos de 12 m não precisam de apito nem de sino, mas têm de ter outro meio de fazer um sinal sonoro eficaz.[12]
• Antes de largar: aprenda os sinais de buzina e de sino que tem de fazer com nevoeiro.[26]
• Antes de largar: leve agulha e carta para poder continuar a navegar se a eletrónica falhar.[25]

Perguntas frequentes

Fontes

As fontes são citadas na língua original.

1. IMO COLREGs Rule 35(a), text published by US Coast Guard Navigation Center (2026-10-14): “A power-driven vessel making way through the water shall sound at intervals of not more than 2 minutes one prolonged blast”
2. IMO COLREGs Rule 35(c), text published by US Coast Guard Navigation Center (2026-10-14): “shall, instead of the signals prescribed in Rule 35 (a) or (b), sound at intervals of not more than 2 minutes three blasts in succession, namely one prolonged followed by two short blasts”
3. IMO COLREGs Rule 35(j), text published by US Coast Guard Navigation Center (2026-10-14): “A vessel of less than 12 meters in length shall not be obliged to give the above mentioned signals but, if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.”
4. IMO COLREGs Rule 35(b), text published by US Coast Guard Navigation Center (2026-10-14): “A power-driven vessel underway but stopped and making no way through the water shall sound at intervals of no more than 2 minutes two prolonged blasts in succession with an interval of about 2 seconds between them.”
5. IMO COLREGs Rule 35(g), text published by US Coast Guard Navigation Center (2026-10-14): “A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds.”
6. IMO COLREGs Rule 19(b), text published by US Coast Guard Navigation Center (2026-10-14): “Every vessel shall proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines ready for immediate maneuver.”
7. IMO COLREGs Rule 19(e), text published by US Coast Guard Navigation Center (2026-10-14): “every vessel which hears apparently forward of her beam the fog signal of another vessel, or which cannot avoid a close-quarters situation with another vessel forward of her beam, shall reduce her speed to be the minimum at which she can be kept on her course.”
8. IMO COLREGs Rule 5, text published by US Coast Guard Navigation Center (2026-10-14): “Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.”
9. IMO COLREGs Rule 10(c), text published by US Coast Guard Navigation Center (2026-10-14): “A vessel, shall so far as practicable, avoid crossing traffic lanes but if obliged to do so shall cross on a heading as nearly as practicable at right angles to the general direction of traffic flow.”
10. IMO COLREGs Rule 32(c), text published by US Coast Guard Navigation Center (2026-10-14): “The term "prolonged blast" means a blast of from four to six seconds duration.”
11. IMO COLREGs Rule 20(c), text published by US Coast Guard Navigation Center (2026-10-14): “The lights prescribed by these Rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility”
12. IMO COLREGs Rule 33(b), text published by US Coast Guard Navigation Center (2026-10-14): “A vessel of less than 12 meters in length shall not be obliged to carry the sound signaling appliances prescribed in Rule 33 (a) but if she does not, she shall be provided with some other means of making an efficient signal.”
13. RNLI (2026-10-14): “When you see fog approaching, immediately do a position fix on your GPS and on your paper chart.”
14. RNLI (2026-10-14): “Make yourself visible and help yourself see other vessels – switch on navigation lights, make sure your radar reflector’s up, and use your radar and AIS (Automatic Identification System).”
15. RNLI (2026-10-14): “Nominate extra crew for lookout duty and check all are wearing lifejackets.”
16. RNLI (2026-10-14): “At a safe speed and a steady course, head for shallower water where you won’t be in any busy shipping lanes. There, drop anchor and sit it out.”
17. RNLI (2026-10-14): “If you’re really worried you’re stuck in a dangerous place, use your VHF radio to call for help.”
18. RNLI (2026-10-14): “keep listening out for engine noise, horns, voices and other signs of vessels nearby.”
19. RNLI (2026-10-14): “Very small vessels like dinghies don’t always show up on the radar, so you’ve got to be extra careful.”
20. RNLI (2026-10-14): “Listen on VHF Ch 16 and, in restricted waters, Ch 13.”
21. RNLI (2026-10-14): “It’s a common misconception that fog always gets ‘burned off’ by the sun as the day progresses; sea fog can still linger well into the afternoon.”
22. RNLI (2026-10-14): “Don’t be tempted to stick on the radio while you’re waiting for the fog to clear, or get distracted by conversation”
23. US National Weather Service (NOAA) (2026-10-14): “Turn on all of your running lights, even in daytime.”
24. US National Weather Service (NOAA) (2026-10-14): “If you are unable to get your bearings, stay put until the fog lifts but make sure you are in a safe location.”
25. US National Weather Service (NOAA) (2026-10-14): “Have a compass available. Even if you don't know where you are in the fog, with a compass you can determine the direction you are navigating.”
26. US National Weather Service (NOAA) (2026-10-14): “Be familiar with horn and bell sounds you should produce to warn others around you when in dense fog.”
27. Transport Canada – Safe Boating Guide (TP 511E) (2026-10-14): “Slow is the only safe speed in fog, mist, rain, smoke and darkness”
28. Maritime and Coastguard Agency (MGN 349) (2026-10-14): “There is no guarantee that a small vessel will consistently show on radar screens”
29. Maritime and Coastguard Agency (MGN 349) (2026-10-14): “All small craft should consider fitting, where practicable, the most effective and appropriate radar reflector or radar target enhancer (RTE) for their circumstances; and ensure those comply with international standards.”
30. IMO COLREGs Rule 32(b), text published by US Coast Guard Navigation Center (2026-10-14): “The term "short blast" means a blast of about one seconds duration.”

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