COLREG Sound Signals
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Fog Signals
Power-driven vessel making way
Power-driven vessel making way through water must sound one prolonged blast at intervals of not more than 2 minutes
Power-driven vessel not making way
Power-driven vessel underway but stopped and making no way through the water must sound at intervals of not more than 2 minutes two prolonged blasts in succession with an interval of about 2 seconds between them.
NUC, RAM, CBD, sailing, fishing, or towing/pushing vessel
Vessels not under command, with restricted maneuverability, constrained by draft, sailing vessel, fishing vessel, or vessel towing/pushing must sound at intervals of not more than 2 minutes three blasts in succession, namely one prolonged followed by two short blasts.
Fishing vessel and RAM at anchor
Vessels with restricted maneuverability and fishing vessels at anchor shall sound one prolonged followed by two short blasts.
Vessel being towed
Vessel being towed if manned must at intervals of not more than 2 minutes sound four blasts in succession, namely one prolonged followed by three short blasts. When practicable, this signal shall be made immediately after the signal made by the towing vessel.
Pilot vessel on duty
Besides usual signals for making way, not making way and anchor, pilot vessel on duty (identity signal)
Vessel at anchor
Vessel at anchor in intervals of not more then 1 minute do rapid ringing of bell for 5 seconds (if longer then 100m this will be followed by 5 seconds of gong), followed by one short blast, prolonged blast, and one short blast.
Vessel aground
Vessel aground must give bell signal, if required - gong as well. In addition - give 3 separate and distinct strokes on the bell before and after the rapid ringing of the bell.
Maneuvering Signals
Altering course to starboard
I am altering my course to starboard
Altering course to port
I am altering my course to port
Operating astern propulsion
I am operating astern propulsion
Danger signal / doubt intentions
Danger signal - I do not understand your intentions / doubt you are taking sufficient action to avoid collision
Overtaking on starboard side
I intend to overtake on your starboard side
Overtaking on port side
I intend to overtake on your port side
Agreement to be overtaken
Agreement to be overtaken
Approaching bend or obstruction
Vessel approaching a bend or channel obstruction
Morse Code / Single Letter Signals
International maritime single-letter signals. Click to hear the morse code.
I have a diver down; keep well clear at slow speed
I am taking in, or discharging, or carrying dangerous goods
Yes (affirmative)
Keep clear of me; I am maneuvering with difficulty
I am altering my course to starboard
I am disabled; communicate with me
I require a pilot
I have a pilot on board
I am altering my course to port
I am on fire and have dangerous cargo; keep well clear
I wish to communicate with you
You should stop your vessel instantly
My vessel is stopped and making no way
No (negative)
Man overboard
Vessel about to put to sea (Blue Peter)
My vessel is healthy and I request free pratique
No specific meaning in single-letter signals
My engines are going astern
Keep clear; engaged in pair trawling
You are running into danger
I require assistance
I require medical assistance
Stop carrying out your intentions and watch for my signals
I am dragging anchor
I require a tug
International distress signal - immediate assistance required