International Regulations for Avoiding Collisions at Sea or IRPCS. The rules are specified in great detail in the regulations and the serious student is encouraged to seek the definitive document. Certain individuals are legally required to carry or possess a copy of the rules, such as the owners and/or operators of certain vessels. These legal requirements vary by jurisdiction. Consult the appropriate maritime authorities for each jurisdiction. Any individual subject to such requirements should obtain a complete, official copy from a government or official source. However, the rules are summarized below.
Part A - General
Part B - Steering and Sailing Rules
Section I - Conduct of Vessels in any Condition of Visibility
- Rule 4 : Application
- Rule 5 : Look-out
- Rule 6 : Safe Speed
- Rule 7 : Risk of Collision
- Rule 8 : Action to Avoid Collision
- Rule 9 : Narrow Channels
- Rule 10 : Traffic Separation Schemes
Section II - Conduct of Vessels in Sight of One Another
- Rule 11 : Application
- Rule 12 : Sailing Vessels
- Rule 13 : Overtaking
- Rule 14 : Head-on Situation
- Rule 15 : Crossing Situation
- Rule 16 : Action by Give-way Vessel
- Rule 17 : Action by Stand-on Vessel
- Rule 18 : Responsibilities Between Vessels
Section III - Conduct of Vessels in Restricted Visibility
Part C - Lights and Shapes
- Rule 20 : Application
- Rule 21 : Definitions
- Rule 22 : Visibility of Lights
- Rule 23 : power driven Vessels Underway
- Rule 24 : Towing and Pushing
- Rule 25 : Sailing Vessels Underway and Vessels Under Oars
- Rule 26 : Fishing Vessels
- Rule 27 : Vessels Not Under Command or Restricted in Their Ability to Maneuver
- Rule 28 : Vessels Constrained by their Draft
- Rule 29 : Pilot Vessels
- Rule 30 : Anchored Vessels and Vessels Aground
- Rule 31 : Seaplanes
- Rule 32 : Definitions
- Rule 33 : Equipment for Sound Signals
Rule 34 : Maneuvering and Warning Signals
(a) When vessels are in sight of one another, a power driven vessel under way, when maneuvering as authorized or required by these Rules, shall indicate that maneuver by the following signals on her whistle:
one short blast to mean “I am altering my course to starboard”;
two short blasts to mean “I am altering my course to port”;
three short blasts to mean “I am operating astern propulsion”.
(b) Any vessel may supplement the whistle signals prescribed in paragraph (a) of this Rule by light signals, repeated as appropriate, whilst the maneuver is being carried out:
(i) these signals shall have the following significance:
one flash to mean “I am altering my course to starboard”;
two flashes to mean “I am altering my course to port”;
three flashes to mean “I am operating astern propulsion”.
(ii) the duration of each flash shall be about one second, the interval between flashes shall be about one second, and the interval between successive signals shall not be less than ten seconds.
(iii) the light used for this signal shall, if fitted, be an all-round white light, visible at a minimum range of 5 miles, and shall comply with the provisions of Annex I to these Regulations.
(c) When in sight of one another in a narrow channel or fairway:
(i) a vessel intending to overtake another shall in compliance with Rule 9 (e)(i) indicate her intention by the following signals on her whistle.
two prolonged blasts followed by one short blast to mean “I intend to overtake you on your starboard side”;
two prolonged blasts followed by two short blasts to mean “I intend to overtake you on your port side”.
(ii) the vessel about to be overtaken when acting in accordance with 9(e)(i) shall indicate her agreement by the following signal on her whistle:
one prolonged, one short, one prolonged and one short blast, in that order.
(d) When vessels in sight of one another are approaching each other and from any cause either vessel fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. Such signal may be supplemented by at least five short and rapid flashes.
(e) A vessel nearing a bend or an area of a channel or fairway where other vessels may be obscured by an intervening obstruction shall sound one prolonged blast. Such signal shall be answered with a prolonged blast by any approaching vessel that may be within hearing around the bend or behind the intervening obstruction.
(f) If whistles are fitted on a vessel at a distance apart of more than 100 meters, one whistle only shall be used for giving maneuvering and warning signals.
- Rule 35 : Sound Signals in Restricted Visibility
- Rule 36 : Signals to Attract Attention
- Rule 37 : Distress Signals
Part E - Exemptions
- Rule 38 : Exemptions