Marine Collision Regulations made easier...

Welcome to the NavAtHome Australia resources section on the International Regulations for the Prevention of Collisions at Sea (IRPCS). This set of regulations was created by the International Maritime Organisation (IMO) in 1972 to prevent collisions between vessels at sea and to enable safe navigation in general. They are regularly updated by the IMO and we should attempt to be informed about changes to them, insofar as they concern us. This can be done here:COLREGs - Preventing Collisions at Sea.

The IRPCS are the "Rules of the Road" that need to be followed on water, just like traffic rules need to be followed on land. It is important to note that while these rules generally apply at sea, national bodies of water can be governed by slightly different rules, which then take priority and need to be consulted separately, such as inland waterways, harbour regulations, among others.

The IRPCS consist of 6 parts A to F with 41 specific rules, plus 4 annexes. Parts B, C and D are especially relevant to us. A complete overview is attached below. You can navigate to every rule in detail, including our explanations and graphics to illustrate the (sometimes) slightly legalistic wording. We will provide the meaning of the rule first, and then the original text.

Happy reading 😀

---

International Regulations for Preventing Collisions at Sea - Overview

Part A – General

• Rule 1 – Application
• Rule 2 – Responsibility
• Rule 3 – General Definitions

---

Part B – Conduct of Vessels

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

• Rule 19 – 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 Manoeuvre
• Rule 28 – Vessels Constrained by their Draught
• Rule 29 – Pilot Vessels
• Rule 30 – Anchored Vessels and Vessels Aground
• Rule 31 – Seaplanes

---

Part D – Sound and Light Signals

• Rule 32 – Definitions
• Rule 33 – Equipment for Sound Signals
• Rule 34 – Manoeuvering 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

---

Part F – Verification of Compliance with the Provisions of the Convention

• Rule 39 – Definitions
• Rule 40 – Application
• Rule 41 – Verification of Compliance

---

ANNEXES

• Annex I - Positioning and technical details of lights and shapes.
• Annex II - Additional signals for fishing vessels fishing in close proximity.
• Annex III - Technical details of sounds signal appliances.
• Annex IV - Distress signals, which lists the signals indicating distress and need of assistance.

Rule 1
Application

This rule states that:

• The IRPCS apply to all vessels upon the high seas and all waters connected to the high seas and navigable by seagoing vessels.
• Special rules can be drafted for waterways connected with the high seas by local authorities.
• Additional lights, shapes and sounds can be designated by governments for warships, convoys and fishing fleets.
• Traffic separation schemes can be created by the IMO.
• If a vessel cannot comply with lights, shapes and sounds prescribed in these rules, the state operating this vessel needs to draft requirements that are in closest possible compliance with the IRPCS.

Rule 2
Responsibility

• Owner, master and crew of a vessel need to comply with these rules without exception.
• When evaluating these rules, the actual circumstances need to be considered and acted-on sensibly.

Rule 3
General Definitions

For the purpose of these Rules, except where the context otherwise requires:

(a) The word vessel includes every description of water craft, including non-displacement craft, WIG craft and seaplanes, used or capable of being used as a means of transportation on water.

(b) The term power-driven vessel means any vessel propelled by machinery.

(c) The term sailing vessel means any vessel under sail provided that propelling machinery, if fitted, is not being used.

(d) The term vessel engaged in fishing means any vessel fishing with nets, lines, trawls or other fishing apparatus which restrict manoeuvrability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict manoeuvrability.

(e) The word seaplane includes any aircraft designed to manoeuvre on water.

(f) The term vessel not under command means a vessel which through some exceptional circumstance is unable to manoeuvre as required by these Rules and is therefore unable to keep out of the way of another vessel.

(g) The term vessel restricted in her ability to manoeuvre means a vessel which from the nature of her work is restricted in her ability to manoeuvre as required by these Rules and is therefore unable to keep out of the way of another vessel.

The term vessels restricted in their ability to manoeuvre shall include, but not be limited to:

• (i) a vessel engaged in laying, servicing or picking up a navigation mark, submarine cable or pipeline;
• (ii) a vessel engaged in dredging, surveying or underwater operations;
• (iii) a vessel engaged in replenishment or transferring persons, provisions or cargo while underway;
• (iv) a vessel engaged in the launching or recovery of aircraft;
• (v) a vessel engaged in mine-clearance operations;
• (vi) a vessel engaged in a towing operation such as severely restricts the towing vessel and her tow in their ability to deviate from their course.

(h) The term vessel constrained by her draught means a power-driven vessel which, because of her draught in relation to the available depth and width of navigable water, is severely restricted in her ability to deviate from the course she is following.

(i) The word underway means that a vessel is not at anchor, or made fast to the shore or aground.

(j) The words length and breadth of a vessel mean her length overall and greatest breadth.

(k) Vessels shall be deemed to be in sight of one another only when one can be observed visually from the other.

(l) The term restricted visibility means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms or any other similar causes.

(m) The term Wing-In-Ground (WIG) craft means a multimodal craft which, in its main operational mode, flies in close proximity to the surface by utilizing surface-effect action.

n) The word mile means nautical mile. A nautical mile is defined as 1852 metres. (equivalant to 1 minute of latitude on a chart)

Rule 4
Application

Rules in Section I apply to any condition of visibility

Rule 5
Maintaining a Look Out

Any 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.

Advice: When sailing, check the blind spots caused by the sails,they are easy to forget. It can help to designate a crew member to put a harness on and go forward when visibility is impaired. Radar is a key tool, and the explicit wording of the coll regs states that you shall keep a look out using all available means. If you have a radar installed, then this implies that you shall use have it operating and use it.

Rule 6
Safe Speed

Any vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.

In determining a safe speed the following factors shall be among those taken into account:

(a) By all vessels:

• (i) the state of visibility;
• (ii) the traffic density including concentrations of fishing vessels or any other vessels;
• (iii) the manoeuvrability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;
• (iv) at night the presence of background light such as from shore lights or from back scatter of her own lights;
• (v) the state of wind, sea and current, and the proximity of navigational hazards;
• (vi) the draught in relation to the available depth of water.

(b) Additionally, by vessels with operational radar:

• (i) the characteristics, efficiency and limitations of the radar equipment;
• (ii) any constraints imposed by the radar range scale in use;
• (iii) the effect on radar detection of the sea state, weather and other sources of interference;
• (iv) the possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;
• (v) the number, location and movement of vessel detected by radar;
• (vi) the more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity.

Advice:- Safe speed applies to more than just the safety of the vessels concerned.

Rule 7
Risk of collision

(a) Any vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists.

If there is any doubt, such risk shall be deemed to exist.

(b) Proper use shall be made of radar equipment if fitted and operational, including long-range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects.

(c) Assumptions shall not be made on the basis of scanty information, especially scanty radar information.

(d) In determining if risk of collision exists, the following considerations shall be among those taken into account:

(i) such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change;

(ii) such risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel or a tow or when approaching a vessel at close range.

Advice:- Take avoiding action early and make it positive so the skipper of the other vessel can see the action your are taking.

Rule 8
Action to avoid collision

(a) Any action taken to avoid collision shall be taken in accordance with the rules of this Part and, if the circumstances of the case admit, be positive, made in ample time and with due regard to the observance of good seamanship.

(b) Any alteration of course and/or speed to avoid collision shall, if the circumstances of the case admit, be large enough to be readily apparent to another vessel observing visually or by radar. A succession of small alterations of course and/or speed should be avoided.

(c) If there is sufficient sea room, alteration of course alone may be the most effective action to avoid a close quarters situation provided that it is made in good time, is substantial and does not result in another close quarters situation.

(d) Action taken to avoid collision with another vessel shall be such as to result in passing at a safe distance.
The effectiveness of the action shall be carefully checked until the other vessel is finally past and clear.

(e) If necessary to avoid collision or allow more time to assess the situation, a vessel shall slacken her speed or take all way off by stopping or reversing her means of propulsion.

(f)

• (i) A vessel which, by any of these Rules, is required not to impede the passage or safe passage of another vessel shall, when required by the circumstances of the case, take early action to allow sufficient sea room for the safe passage of the vessel.
• (ii) A vessel required not to impede the passage or safe passage of another vessel is not relieved of this obligation if approaching the other vessel so as to involve risk of collision and shall, when taking action, have full regard to the action which may be required by the rules of this part.
• (iii) A vessel the passage of which is not to be impeded remains fully obliged to comply with the rules of this part when the two vessels are approaching one another so as to involve risk of collision.

Click on the images to see alternative scenarios

Rule 9
Narrow channels

(a) A vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable.

(b) A vessel of less than 20 metres in length or a sailing vessel shall not impede the passage of a vessel which can navigate safely only within a narrow channel or fairway.

(c) A vessel engaged in fishing shall not impede the passage of any other vessel navigating within a channel or fairway.

(d) A vessel shall not cross a narrow channel or fairway if such crossing impedes the passage of a vessel which can navigate safely only within such channel or fairway.

The latter vessel may use the sound signal prescribed in Rule 34 paragraph (d) if in doubt as to the intention of the crossing vessel.

(e)

• (i) In a narrow channel or fairway when overtaking can take place only if the vessel to be overtaken has to take action to permit safe passing, the vessel intending to overtake shall indicate her intention by sounding the appropriate signal prescribed in Rule 34 subparagraph (c) (i). The vessel to be overtaken shall, if in agreement, sound an appropriate signal as prescribed in Rule 34 subparagraph (c)
• (ii) and take steps to permit safe passing. If in doubt she may sound the signals prescribed in Rule 34 paragraph (d).
• (iii) This Rule does not relieve the overtaking vessel of her obligation under Rule 13.

(f) A vessel nearing a bend or an area of a narrow channel or fairway where other vessels may be obscured by an intervening obstruction shall navigate with particular alertness and caution and shall sound the appropriate signal prescribed in Rule 34 paragraph (e).

(g) Any vessel shall, if the circumstances of the case admit, avoid anchoring in a narrow channel.

Click on the images to see different scenarios

Rule 10
Separation schemes

(a) This Rule applies to traffic separation schemes adopted by the Organization and does not relieve any vessel of her obligation under any other Rule.

(b) A vessel using a traffic separation scheme shall:

• (i) proceed in the appropriate traffic lane in the general direction of traffic flow for that lane;
• (ii) so far as practicable keep clear of a traffic separation line or separation zone;
• (iii) normally join or leave a traffic lane at the termination of the lane, but when joining or leaving from either side shall do so at as small an angle to the general direction of traffic flow as practicable.

(c) 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.

(d)

• (i) A vessel shall not use inshore traffic zones when she can safely use the appropriate traffic lane within the adjacent traffic separation scheme. However, vessels of less than 20 metres in length, sailing vessels and vessels engaged in fishing may use the inshore traffic zone.
• (ii) Notwithstanding subparagraph (d) (i), a vessel may use an inshore traffic zone when en route to or from a port, offshore installation or structure, pilot station or any other place situated within the inshore traffic zone, or to avoid immediate danger

(e) A vessel other than a crossing vessel or a vessel joining or leaving a lane, shall not normally enter a separation zone or cross a separation line except:

• (i) in case of emergency to avoid immediate danger;
• (ii) to engage in fishing within a separation zone.

(f) A vessel navigating in areas near the terminations of traffic separation schemes shall do so with particular caution.

(g) A vessel shall so far as practicable avoid anchoring in a traffic separation scheme or in areas near its terminations.

(h) A vessel not using a traffic separation scheme shall avoid it by as wide a margin as is practicable.

(i) A vessel engaged in fishing shall not impede the passage of any vessel following a traffic lane.

(j) A vessel of less than 20 metres in length or a sailing vessel shall not impede the safe passage of a power-driven vessel following a traffic lane.

(k) A vessel restricted in her ability to manoeuvre when engaged in an operation for the maintenance of safety of navigation in a traffic separation scheme is exempted from complying with this Rule to the extent necessary to carry out the operation.

(l) A vessel restricted in her ability to manoeuvre when engaged in an operation for the laying, servicing or picking up of a submarine cable, within a traffic separation scheme, is exempted from complying with this Rule to the extent necessary to carry out the operation.