Rule 7 — Deciding That Risk of Collision Exists

What the rule requires

One test in Rule 7 produces a mandatory conclusion rather than an opinion: such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change 33 CFR §83.07. The rule attaches no distance to that finding, no closing speed, no vessel size and no number for what counts as "appreciably." A steady compass bearing on something that is approaching settles the question by itself.

The phrase every wheelhouse uses for this is CBDR — constant bearing, decreasing range. It is the standard device and it is sound, because "approaching" in the rule supplies the closing-range half. Where CBDR misleads is in its converse: mariners hear it long enough that they start treating a moving bearing as clearance, and the rule says no such thing.

That is the business of Rule 7(d)(ii). Risk may sometimes exist even when an appreciable bearing change is evident, and the rule names when to suspect it: approaching a very large vessel, approaching a tow, or approaching a vessel at close range. Bearing drift on a 1,100-foot ship or on a tug with 1,200 feet of wire out behind her is drift measured to one point on a target that occupies a large arc, and the same drift at half a mile buys far less water than it does at six miles.

Before either of those, Rule 7(a) sets the duty to look for the answer at all: every vessel shall use all available means appropriate to the prevailing circumstances and conditions to determine if risk of collision exists, and if there is any doubt such risk shall be deemed to exist. Doubt is not a reason to keep watching before you decide. Doubt is the decision, made for you, in favour of risk.

The radar duties

Rule 7(b) switches on for a specific condition — radar if fitted and operational — and then imposes two things: long-range scanning to obtain early warning of risk of collision, and radar plotting or equivalent systematic observation of detected objects.

Read that trigger closely. It does not depend on whether your vessel is required to carry radar. A set aboard and working is a set you are obliged to use properly, and using it properly means the long scale as well as the close one.

Rule 7(c) closes the gap a single observation leaves: assumptions shall not be made on the basis of scanty information, especially scanty radar information. One paint on a screen, one bearing, one glance at a set left on the six-mile scale — none of that supports a conclusion either way.

Nothing in Rule 7 provides a test that clears you. It gives you two routes to "risk exists" and one warning that risk may exist even when the numbers look comfortable. There is no clause reading "risk does not exist when…," and distractors built on that shape are wrong on their face.

The two regimes

Rule 7 is identical under both sets — Inland Rule 7 is word for word the same as COLREGs Rule 7. A question turning on risk of collision has no International-versus-Inland trap in it, which is worth knowing so you do not waste time hunting for one. Its neighbour is a different matter: Inland Rule 8 differs from COLREGs Rule 8, so a question about what you do once risk exists needs the regime checked, and a question about whether risk exists does not.

You are in doubt whether risk of collision exists with a vessel four miles off your port bow. What is your finding?

Risk of collision exists. Rule 7(a) resolves doubt against you: if there is any doubt, such risk shall be deemed to exist. You do not get to record "uncertain" and carry on at the same speed — the rule converts your uncertainty into a positive finding, and everything that follows from a finding of risk now applies.

Telling it apart

Rules 5, 7 and 8 sit in sequence, and the criterion that separates them is which step of the collision-avoidance process the rule governs. Candidates lose points by answering the step next door.

Rule 5 — Look-out. Gathering. Every 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 33 CFR §83.05. Most often misfiled when a question asks how you determine risk exists and the candidate picks the answer about posting a lookout.
Rule 7 — Risk of collision. Concluding. Takes what the lookout and the radar produced and tells you what finding to make, including the two findings the rule makes for you.
Rule 8 — Action to avoid collision. Acting. Action shall be positive, made in ample time and with due regard to the observance of good seamanship, and its effectiveness shall be carefully checked until the other vessel is finally past and clear. Misfiled when a candidate reaches for "alter course to starboard" on a question that only asked whether risk of collision existed.

Rule 7 assigns nobody give-way status and nobody stand-on status. An option that says the stand-on vessel must keep out of the way when risk of collision exists is answering a question about Rules 16 and 17, and it is not what Rule 7 does.

Working a question

You have the watch on a 78-foot small passenger vessel, radar fitted and operational, clear night, making 12 knots. A contact appears broad on the starboard bow at eight miles.

Put the radar to work at range. Long-range scanning is required of a fitted, operational set precisely so the contact is yours at eight miles rather than at two, 33 CFR §83.07. Detection alone is not yet information you may act on.
Start a systematic observation. Rule 7(b) requires radar plotting or equivalent systematic observation, and Rule 7(c) forbids assumptions on scanty radar information. So: repeated compass bearings and ranges at fixed intervals, logged, not one look and a hunch.
Read the bearings. 052° at 8.0 miles, 052° at 6.4 miles, 051.5° at 4.8 miles. The bearing has moved half a degree in twelve minutes while the range has closed by 3.2 miles.
Make the finding the rule makes. The compass bearing of an approaching vessel is not appreciably changing, so risk of collision shall be deemed to exist. Nothing further is needed — not the target's identity, not her course and speed, not a CPA figure. Those refine your action; they do not qualify the finding.
Notice which rule takes over. What you now do — and how large, how early, and how it is checked — comes from Rule 8, and Inland Rule 8 is not identical to the International rule.

Now change one thing. The bearing opens steadily from 038° to 046° over twelve minutes, and the contact resolves as a tug with a long tow, range now 1.2 miles.

Do not treat the opening bearing as clearance. Rule 7(d)(ii) names this case twice over: a tow, and a vessel at close range. Risk may exist despite an appreciable bearing change.
Ask what the bearing was taken on. A bearing to the tug's lights says nothing certain about where the barge is tracking, and the drift you measured is spread across a target far longer than the one you plotted.
Resolve the doubt the way the rule does. If you are in any doubt after that, risk of collision is deemed to exist, and the eight degrees of bearing change do not overturn it.

Where candidates lose the point

Picking a distance. Options offering "when meeting or crossing within one mile" or "when the vessels will pass within half a mile" are attractive because they sound like the sort of number this exam loves. Rule 7 contains no distance whatsoever. The test in 7(d)(i) is the compass bearing.

Treating a changing bearing as proof of safety. This is the most expensive error on the water and a common wrong answer on paper. Rule 7(d)(ii) exists solely to deny it, for a very large vessel, for a tow, and at close range.

Over-correcting into "risk always exists when the bearing changes appreciably." The rule says risk may sometimes exist in that case. "Shall be deemed" belongs to the steady bearing and to doubt; "may sometimes" belongs to the appreciable change. An option that upgrades the second to the first is wrong, and one that downgrades the first to the second is also wrong.

Substituting a relative bearing for a compass bearing. The rule specifies compass bearing. A contact held steady over the starboard bow while your own head has swung ten degrees is not a steady compass bearing, and a contact whose relative bearing is walking aft while you come round to starboard may be dead steady by compass. Candidates who have spent a career conning by "she's on the bow" answer this one from habit.

Deciding radar is optional because carriage is optional. The trigger in 7(b) is if fitted and operational, not whether the vessel is required to carry it. On a 42-foot uninspected passenger vessel with a working set, long-range scanning and systematic observation are required of you.

Check yourself

(Both International & Inland) You observe an approaching vessel and its compass bearing does not appreciably change. What is the situation?

Risk of collision exists — the rule states it shall be deemed to exist on that fact alone. No distance, closing speed or vessel type conditions it.

(Both International & Inland) Which of these establishes that risk of collision exists: the vessels will pass within one mile; there is any doubt that risk exists; the other vessel is a tow; four vessels are in company?

Any doubt that risk exists. Rule 7(a) deems risk to exist wherever doubt is present. The one-mile figure appears nowhere in the rule, and a tow is relevant only as a case in which risk may exist despite an appreciable bearing change.

(Both International & Inland) A large containership is approaching and her compass bearing is opening steadily. May you conclude that no risk of collision exists?

No. Risk may sometimes exist even when an appreciable bearing change is evident, particularly when approaching a very large vessel, a tow, or a vessel at close range. Two of those three cases can apply to a ship of that size passing close, and if doubt remains, risk is deemed to exist.

(Both International & Inland) Your radar is not required by regulation on your vessel, but it is fitted and working. What does Rule 7 require of it?

Proper use, because the trigger is that the set is fitted and operational. That means long-range scanning to obtain early warning of risk of collision, plus radar plotting or equivalent systematic observation of detected objects.

(Both International & Inland) You have one radar contact seen once at ten miles, no bearings taken. What may you conclude about her intentions?

Nothing. Assumptions shall not be made on the basis of scanty information, especially scanty radar information. Systematic observation is required before the information supports any conclusion.

(Both International & Inland) You have determined that risk of collision exists with a vessel crossing from your starboard side. Does Rule 7 tell you to alter course to starboard?

No. Rule 7 determines only whether risk of collision exists; it assigns no give-way or stand-on status and prescribes no manoeuvre. Action, its size and its timing come from Rule 8, and there the Inland and International texts are not identical.

(Both International & Inland) A question is labelled "(Inland Only)" and asks when risk of collision is deemed to exist. Does your answer change from the International rule?

No. Inland Rule 7 is word for word identical to the International rule, so the steady-compass-bearing test and the doubt provision read the same under both.