Rule 7: is there a risk of collision?

What does COLREGs Rule 7 say?

Rule 7(a): every vessel must use all available means appropriate to the prevailing circumstances and conditions to determine whether risk of collision exists — and 'if there is any doubt', the risk is deemed to exist.

Rule 7(b): radar, if fitted and operational, must be used properly, including long-range scanning for early warning of risk of collision, and radar plotting or 'equivalent systematic observation' of detected objects.

Rule 7(c): assumptions must not be made on the basis of scanty information, especially scanty radar information.

Rule 7(d) sets out two considerations that must be among those taken into account — the steady compass bearing, and the cases where a changing bearing is not enough.

What does 'if there is any doubt' mean in practice?

That doubt is settled one way only. If you cannot be sure there is no risk of collision, the rule treats the risk as existing, and you plan and act on that basis. 'It will probably pass clear' is not an answer the rule accepts while doubt remains.

How does Rule 7 relate to Rule 5?

Rule 5 requires a proper look-out by sight and hearing and by all available means, so as to make a full appraisal of the situation and of the risk of collision. Rule 7 picks up where the look-out leaves off: once something is seen, heard or detected, it governs how you decide whether it is a risk.

How do you tell if risk of collision exists?

The rule's best-known test is in 7(d)(i): risk of collision is deemed to exist if the compass bearing of an approaching vessel does not appreciably change. In practice that means a series of bearings over time — by compass, or by the radar's bearing line read as a true bearing on a stabilised (north-up or course-up) display — together with the range, so you can see whether the bearing is steady and the range closing.

One bearing tells you nothing about whether it is changing. The test needs several.

Why a compass bearing and not a relative bearing?

Because a relative bearing moves with your own heading. If you yaw, or alter course, a vessel's bearing relative to your bow changes even though the geometry between you has not. The compass bearing is measured from a fixed reference, so a change in it reflects real relative movement.

Can there be a risk of collision when the bearing is changing?

Yes. Rule 7(d)(ii) says risk may sometimes exist even when an appreciable bearing change is evident — 'particularly when approaching a very large vessel or a tow' or a vessel at close range.

With a long ship or a tow, the bearing of one end can draw clear while another part of her is still on a steady bearing; a bearing taken on her bow or her masthead lights is not a bearing of her stern or of the tow behind. At close range, a change that looks appreciable can still leave far too little room.

What counts as 'proper use' of radar under Rule 7(b)?

Two things the rule names: long-range scanning, so you get early warning rather than finding a contact already close; and radar plotting or equivalent systematic observation of what you detect. The point is a record over time — successive ranges and bearings, by hand or by the radar's tracking functions — not a glance at a single picture.

It applies only if radar is fitted and operational. But if it is, Rule 7(b) makes using it properly a requirement, not an option.

What is 'scanty information'?

Anything too thin to support a conclusion: a single radar observation, one bearing, a plot over too short a time, or a contact seen once and then lost. Rule 7(c) forbids building an assumption on it and singles out radar information. In our view the same caution applies to any one source taken alone — what another vessel's AIS shows, for instance, is only what she is transmitting.

Does Rule 7 still apply in restricted visibility?

Yes — it is in Part B, Section I, which covers any condition of visibility. Rule 19(d) builds on it: a vessel that detects another by radar alone must determine whether a close-quarters situation is developing and/or risk of collision exists, and if so take avoiding action in ample time. Rule 19(c) requires due regard to the restricted visibility when complying with the Section I rules, Rule 7 included.

How might Rule 7 come up in an MCA oral?

As the first step in a collision scenario, before what you would do about it. Examples of the kind of question to be ready for:

“How do you determine whether risk of collision exists?”

“The bearing of a vessel on your starboard bow is changing slowly. Is there a risk of collision?”

“Why a compass bearing rather than a relative one?”

“You're closing a tug with a long tow. What does Rule 7 warn you about?”

“What does proper use of radar mean?”

Where do candidates go wrong on Rule 7?

The common slips: deciding on one bearing or one radar picture; talking about relative bearings; forgetting the 'any doubt' sentence; and assuming a changing bearing means a safe passing with a very large vessel, a tow or a vessel at close range. Say how you would establish the risk, not just that you would 'monitor it'.