Nebbia e visibilità ridotta in acqua: cosa fare

Ultima verifica: 14 ottobre 2026

Passo per passo

1. Fai subito il punto

   Quando vedi arrivare la nebbia, annota subito la tua posizione sul GPS e sulla carta nautica cartacea.[13]

2. Rallenta

   Piano è l’unica velocità sicura nella nebbia. Procedi a una velocità che ti permetta di fermarti o di accostare in tempo, e tieni il motore pronto a manovrare immediatamente.[27][6]

3. Luci accese, riflettore issato

   Accendi le luci di navigazione, anche di giorno, e assicurati che il riflettore radar sia issato.[11][23][14]

4. Emetti il segnale da nebbia

   Secondo il COLREG, una barca a motore in moto sull’acqua emette un suono prolungato (4–6 secondi) almeno ogni 2 minuti; una barca a vela emette un suono prolungato e due brevi. Una barca sotto i 12 m può invece emettere un altro segnale sonoro efficace almeno ogni 2 minuti.[1][2][3][10]

5. Guarda e ascolta

   Metti altro equipaggio di vedetta e controlla che tutti indossino il giubbotto di salvataggio. Spegni la musica e resta in ascolto di motori, sirene, voci e segnali da nebbia.[8][15][18][22]

6. Usa radar e AIS, ma non fidarti ciecamente

   Usa radar e AIS se li hai. Ricorda che le piccole barche possono non comparire sul radar delle altre navi, anche con un riflettore.[14][19][28]

7. Senti un segnale a proravia? Rallenta al minimo

   Se senti a proravia il segnale da nebbia di un’altra nave, riduci alla velocità minima che ti permette di mantenere la rotta, e fermati se necessario, finché il pericolo non è passato.[7]

8. Esci dalle rotte delle navi

   A velocità di sicurezza e con rotta costante, dirigiti verso acque meno profonde lontano dalle rotte trafficate, poi ancorati e aspetta. Se devi attraversare una corsia di traffico, attraversala perpendicolarmente al flusso del traffico.[16][9]

9. Segnale all’ancora e ascolto sul canale 16

   All’ancora, una nave suona rapidamente la campana per circa 5 secondi almeno ogni minuto; una barca sotto i 12 m può invece emettere un altro segnale sonoro efficace almeno ogni 2 minuti. Resta in ascolto sul canale 16 VHF.[5][3][20]

10. Chiedi aiuto se sei in pericolo

    Se pensi di essere bloccato in un punto pericoloso, usa la radio VHF per chiedere aiuto.[17]

Cosa non fare

• Non mantenere la tua velocità normale. Piano è l’unica velocità sicura nella nebbia.[27]
• Non dare per scontato che le navi ti vedano sul radar o sull’AIS.[19][28]
• Non ascoltare la radio e non distrarti chiacchierando; ti servono le orecchie.[22]
• Non attraversare una rotta di navigazione in diagonale; se devi attraversarla, fallo perpendicolarmente.[9]
• Non dare per scontato che il sole dissolva la nebbia; la nebbia marina può durare fino a pomeriggio inoltrato.[21]

Prima di salpare

• Prima di salpare: monta il miglior riflettore radar praticabile per la tua barca.[29]
• Prima di salpare: porta un mezzo di segnalazione sonora funzionante. Le barche sotto i 12 m non devono avere fischio e campana, ma devono avere un altro mezzo per emettere un segnale sonoro efficace.[12]
• Prima di salpare: impara i segnali di sirena e di campana da emettere nella nebbia.[26]
• Prima di salpare: porta bussola e carta nautica per poter navigare anche se l’elettronica si guasta.[25]

Domande frequenti

Fonti

Le fonti sono citate nella lingua originale.

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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