subject: International Regulations For Preventing Collisions At Sea [print this page] Summary of the rules Summary of the rules
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
1. Application
(a) These Rules shall apply to all vessels upon the high seas and in all waters connected therewith navigable by seagoing vessels.
(b) Nothing in these Rules shall interfere with the operation of special rules made by an appropriate authority for roadsteads, harbours, rivers, lakes or inland waterways connected with the high seas and navigable by seagoing vessels. Such special rules shall conform as closely as possible to these Rules.
(c) Nothing in these Rules shall interfere with the operation of any special rule made by the Government of any State with respect to additional station or signal lights, shapes or whistle signals for ships of war and vessels proceeding under convoy, or with respect to additional station or signal lights or shapes for fishing vessels engaged in fishing as a fleet. These additional station or signal lights, shapes or whistle signals shall, so far as possible, be such that they cannot be mistaken for any light, shape or signal authorised elsewhere under these Rules.
(d) Traffic separation schemes may be adopted by the Organization for the purpose of these Rules.
(e) Whenever the Government concerned shall have determined that a vessel of any special construction or purpose cannot comply with the provisions of any of these Rules with respect to the number, position, range or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signalling appliances, such vessel shall comply with such other provisions in regard to the number, position, range or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signalling appliances, as her Government shall have determined to be the closest possible compliance with these Rules in respect of that vessel.
2. Responsibility
(a) Nothing in these Rules shall exonerate any vessel, or the owner, master or crew thereof, from the consequences of any neglect to comply with these Rules or of the neglect of any precaution which may be required by the ordinary practice of seamen, or by the special circumstances of the case.
(b) In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger.
3. General Definitions
For the purpose of these Rules, except where the context otherwise requires:
(a) The word essel 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 ower-driven vessel means any vessel propelled by machinery.
(c) The term ailing vessel means any vessel under sail provided that propelling machinery, if fitted, is not being used.
(d) The term essel 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 eaplane includes any aircraft designed to manoeuvre on the water.
(f) The term essel 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 essel 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 essels 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 essel 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 nderway means that a vessel is not at anchor, or made fast to the shore, or aground.
(j) The words ength and readth 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 estricted 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 ing-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.
Part B - Steering and sailing
Section I (for any visibility)
4. Application
The rules apply in any visibility (e.g. in sight or in restricted visibility).
5. Look-out
Every vessel must at all times keep a proper look-out by sight (day shape or lights by eyes or visual aids), hearing (sound signal or Marine VHF radio) and all available means (e.g. Radar, ARPA, AIS, GMDSS...) in order to judge if risk of collision exists.
6. Safe speed
Any vessel must proceed at a safe speed, which she can to take action to avoid collision and able to stop within the distance for the prevailing conditions (including the visibility, weather, traffic condition, background lights, her manoevrability (e.g. stopping distance and turning circles) and draft in relation with the available water).
When radar is in use, also consider if there is any limitations of the equipment, range scale in use, weather and other interference, weak targets, targets density and movement, and use radar to judge the visibility is much accurate for objects nearby.
7. Risk of Collision
Vessels must use all available means to determine the risk of a collision, including the use of radar (if available) to get early warning of the risk of collision by radar plotting or equivalent systematic observation of detected objects. (e.g. ARPA, AIS).
If the distance of any vessel is reduced and her compass bearing does not change much or a large vessel or towing vessel at close distance or if in doubt, risk of collision shall be deemed to exist.
8. Action to avoid collision
Actions taken to avoid collision should be:
positive
obvious
made in good time
9. Narrow channels
A vessel proceeding along a narrow channel must keep to starboard.
Small vessels or sailing vessels must not impede (larger) vessels which can navigate only within a narrow channel.
Ships must not cross a channel if to do so would impede another vessel which can navigate only within that channel.
10. Traffic separation schemes
Ships must cross traffic lanes steering a course "as nearly as practicable" at right angles to the direction of traffic. This reduces confusion and enables that vessel to cross the lane as quickly as possible.
Section II (for vessels in sight of one another)
11. Application
The following rules 11-18 applies to vessels in sight of one another. (Section II does not apply if in restricted visibility, see Section III)
12. Sailing vessels
Two sailing vessels approaching one another must give-way as follows:
Port gives way to Starboard. When each has the wind on a different side, the vessel which has the wind to port must give way;
Windward gives way to leeward. When both have the wind on the same side, the vessel which is windward must give way to the vessel which is leeward;
Unsure port gives way. If a vessel, with the wind on the port side, sees a vessel to windward and cannot determine whether the other vessel has the wind on the port or the starboard side, they must give way.
13. Overtaking
Notwithstanding anything contained in part B, sections I and II, an overtaking vessel must keep well clear of the vessel being overtaken.
14. Head-on situations
When two power-driven vessels are meeting head-on both must alter course to starboard so that they pass on the port side of the other.
15. Crossing situations
When two power-driven vessels are crossing, the vessel which has the other on the starboard side must give way.
16. The give-way vessel
The give-way vessel must take early and substantial action to keep well clear.
17 The stand-on vessel
The stand-on vessel may take action to avoid collision if it becomes clear that the give-way vessel is not taking appropriate action.
18. Responsibilities Between Vessels
Except in narrow channels, traffic schemes, and when overtaking (i.e. rules 9, 10, and 13)
A power-driven vessel must give way to:
NUC a vessel not under command;
CBD a vessel constrained by draft
RAM a vessel restricted in ability to maneuver;
Fish a vessel engaged in fishing;
Sail a sailing vessel.
A sailing vessel must give way to:
NUC a vessel not under command;
CBD a vessel constrained by draft
RAM a vessel restricted in ability to maneuver;
Fish a vessel engaged in fishing.
A vessel engaged in fishing when underway shall, so far as possible, keep out of the way of:
NUC a vessel not under command;
CBD a vessel constrained by draft
RAM a vessel restricted in her ability to maneuver.
Any vessel other than a vessel not under command or a vessel restricted in her ability to maneuver shall, if the circumstances of the case admit, avoid impeding the safe passage of a vessel constrained by her draft, exhibiting the signals in Rule 28.
A vessel constrained by her draft shall navigate with particular caution having full regard to her special condition.
A seaplane on the water shall, in general, keep well clear of all vessels and avoid impeding their navigation. In circumstances, however, where risk of collision exists, she shall comply with the Rules of this Part.
f) i) A WIG craft when taking off, landing and in flight near the surface shall keep well clear of all other vessels and avoid impeding their navigation
ii) A WIG craft operating on the water surface shall comply with the rules of this part as a power driven vessel.
Section III (for restricted visibility)
19. Restricted visibility
(a) Rule 19 applies to vessels (not in sight of one another) in or near of restricted visibility waters.
(b) All ships shall procede at a safe speed for the condition of visibility (see Rule 6). A power-driven vessel shall put her engine(s) on stand-by for immediate use or stop (particularly for a large ocean going vessel may take long time to get her engine ready to use).
(c) All ships shall comply with the Section I of this Part (e.g. Rule 5.lookout, 6.safe speed, 7.risk of collision, 8.action to avoid collision, 9. Narrow Channel & 10. TSS) for the visibility condition.
(d) Take early and substantial action to avoid collision if detecting another vessel by use radar alone (not in sight), but:-
1. any change of course to port for a vessel forward of the beam should be avoided except for a vessel being overtaken (e.g. determined by radar plot),
2. any change of course toward a vessel abeam or abaft the beam should be avoided.
when hear any unknown fog signal of another vessel apparently forward should reduce the speed to minimum or make all way off (stop all water speed by astern engine) and navigate with extreme caution unless risk of collision not exist (e.g. determined by radar plot, but aware of small crafts may not able be detected or mis-identified in busy waters).
General requirement and application of this rule:
when a vessel navigating or under way at sea inside or nearby (within audible range 1 to 2 n.m. of fog signal) an area of fog, heavy rain or other causes of restricted visibility;
turn on appropriate navigational lights;
switch on appropriate sound signal (this is important as some other vessel may not have radar and may not able to detect your vessel; often collisions in fog with small vessels are caused by vessels not giving sound signals; it is advisable to anchor or stay away from a busy shipping route for small boats when not being able to properly use radar);
get your engine ready to stop at any time and reduce to safe speed in accordance to rule 6 so that at least you could stop or turn your vessel (refer to your stopping distance and advance distance of turning circles) within half of the distance of the visibility in busy water as some small boats may not have radar, nor may they be detected by radar and the audible range of their fog signal may be less than 0.5 n.m.
keep proper lookout by sight, hearing and plot all radar targets. (even small targets as they may not be apparent to you when they show only small changes of course and speed);
the radar (anti-clutter rain, sea and range scale) should be properly adjusted to the condition of visibility and your speed;
stop your vessel when you hear any fog signal and avoid altering course to port if the intention of the target on the radar is not known forward of the beam of your vessel;
take early action to stop or alter course and keep passing other vessels at safe distance (a few minutes and few hundred meters before collision; being too close to take action is not safe enough even when you are small vessel as the collision avoiding action of other large vessels may be delayed as their manoevrability is very slow due to their size).
Part C - Lights and shapes
20. Application
Rules concerning lights apply from sunset to sunrise.
21. Definitions
Gives definitions for various types of light. 'Sidelights' means a green light on the starboard side and a red light on the port side.
22. Visibility of lights
Lights must be visible as follows;
In vessels of 50metres (164ft) or more in length:
a masthead light, 6 nautical miles;
a sidelight, 3 miles;
a towing light, 3 miles;
a white, red, green or yellow all-around light, 3 miles.
In vessels between 1250 metres (39164ft) in length;
a masthead light, for vessel longer than 20metres (66ft), 5 miles; for vessel shorter than 20metres (66ft), 3 miles;
a sidelight, 2 miles;
a sternlight, 2 miles;
a white, red, green or yellow all-round light, 2 miles.
In vessels less than 12metres (39ft) in length:
a masthead light, 2 miles;
a sidelight, 1 mile;
a towing light, 2 miles;
a white, red, green or yellow all-around light, 2 miles.
23. Lights displayed by power-driven vessels underway
A power-driven vessel underway must display:
a masthead light forward;
If over 50metres (164ft) length, then also a second masthead light aft and higher than the forward one;
sidelights;
a sternlight.
A hovercraft must also display an all-round flashing yellow light.
A wing-in-ground craft must also display a bright all-round flashing red light when taking off, landing, or flying near the surface.
A power-driven vessel of less than 12metres (39.4ft) may display only an all-round white light and sidelights.
A power-driven vessel of less than 7metres (23.0ft) whose maximum speed does not exceed 7knots (13km/h; 8mph) may display only an all-round white light.
24. Lights for vessels towing and pushing
A power driven vessel when towing must show
two masthead lights on top of each other, instead of the masthead(s) prescribed in Rule 23;
sidelights;
a sternlight;
a towing light vertically above the sternlight;
a diamond shape if the tow is longer than 200metres (656ft).
if a pushing vessel and the vessel it is pushing are rigidly connected, they count together as a power driven vessel and must show the light prescribed by Rule 23.
If the pushing vessel and vessel being pushed are not rigidly connected, they must instead show:
two masthead lights on top of each other, instead of the masthead(s) prescribed in Rule 23;
sidelights;
a sternlight.
Power driven vessels larger than 50metres (164ft) which are towing or pushing and are not part of a composite unit must also show:
a second masthead abaft of and higher than the forward one (vessels smaller than 50 metres may also show this light).
Vessels being towed that are not inconspicuous or partly submerged must show:
sidelights;
a sternlight;
a diamond shape if the tow is longer than 200metres (656ft).
Any number of vessels being towed or pushed together shall be lit as one vessel, and
a vessel being pushed ahead must show sidelights at its forward end if it is not part of a composite unit;
a vessel being towed alongside must show a sternlight and sidelights at its forward end.
A vessel being towed that are inconspicuous or partly submerged must show:
if it is narrower than 25metres (82ft), one all-round white light near the forward end (except if it is a dracone) and one near the after end;
if it is wider than 25metres (82ft), then also two all round white lights at the extremities of its breadth;
if it is longer than 100metres (328ft), then in a series of such all round white lights spaced no further than 100metres (328ft) apart;
a diamond shape near the end of the last vessel, and, if the tow is longer than 200metres (656ft), another diamond shape as far forward as possible.
If for any reason it is not possible to light the vessel according to these rules, all possible measures must be taken to light the vessel and indicate
