Rule 7 explains how to decide whether risk of collision exists. Every vessel shall use all available means appropriate to the prevailing circumstances and conditions to make that assessment. If there is any doubt, such risk shall be deemed to exist.
- 1Risk of collision shall be deemed to exist when the compass bearing of an approaching vessel does not appreciably change.
- 2A noticeable bearing change does not automatically remove the risk. Collision risk may still exist, especially when approaching a very large vessel, a tow, or a vessel at close range.
IMO COLREG 1972Official text
Full wording of the rule, reproduced from the official source below.
(a) Every 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.STCW Bridge Watch Lens
Rules 4–10 apply in any visibility.
Rules 11–18 apply to vessels in sight of one another; Rule 19 applies to vessels not in sight when navigating in or near an area of restricted visibility.
Build the traffic picture with sight, hearing, radar/ARPA and chart context.
Do not let AIS or one isolated bearing replace systematic observation.
After manoeuvring, keep monitoring bearing, range, CPA/TCPA and passing distance until the other vessel is finally past and clear.
Exam Focus
Start every scenario by classifying the encounter: overtaking, head-on, crossing, narrow channel, traffic separation, or restricted visibility.
For vessels in sight, every overtaking vessel keeps clear until finally past and clear.
Rule 13 takes precedence over Part B Sections I and II; it does not override the other Parts of COLREG.
Collision risk may exist even with an appreciable bearing change, particularly when approaching a very large vessel or a tow, or at close range.
A nearly steady compass bearing is not the only warning.
Key Takeaways
A steady or nearly steady bearing is a classic collision-warning sign
If there is doubt, the Rules tell you to treat the risk as real
Scanty radar information is not a safe basis for assumptions
Radar must be used systematically, not casually
Common Mistakes
Assuming a slight bearing drift means there is no danger
Failing to plot or systematically track a target before deciding the situation is safe
Treating AIS data as if it replaces Rule 7 assessment
Test Your Knowledge
Practise this topic and review the explanation for each answer.
More rules in this Part
- ApplicationRules in Section I apply in any condition of visibility.
- Look-outEvery vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means.
- Narrow ChannelsA vessel proceeding along the course of a narrow channel shall keep as near to the outer limit of the channel which lies on her starboard side.
- Traffic Separation SchemesVessels using traffic separation schemes shall proceed in the appropriate traffic lane in the general direction of traffic flow.
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