COLREGs · Rule 7 · 33 CFR §83.07
Risk of Collision
Every vessel shall use all available means to determine if risk of collision exists. If there is any doubt, such risk shall be deemed to exist. Compass bearings of an approaching vessel are the canonical method.
What does Rule 7 actually say?#
Source
Practice this rule#
One real exam question on this rule, cited to source. No sign-up.
Under the International Rules, the Steering and Conduct Rules in Section II apply ______.
Does Inland Rule 7 change anything?#
Inland Rule 7 is 33 CFR §83.07, reproduced above, and carries no exam-relevant divergence from COLREGs Rule 7. One answer serves both the International and the Inland version of a Rules of the Road question on this rule — which is worth knowing precisely because several neighbouring rules do not work that way.
21 of 38 rules differ somewhere; the five the exam leans on are Rule 9, Rule 10, Rule 24, Rule 28 and Rule 34, side by side on Inland vs International Rules.
Why it shows up on the exam#
Rule 7 is the source of the 'constant bearing, decreasing range' (CBDR) test. Watch for questions where the bearing is changing slowly toward the bow — still risk of collision for very large vessels at close range.
What does the exam actually test here?#
The default
Doubt means risk exists
Rule 7(a) requires every vessel to use all available means appropriate to the circumstances to determine whether risk of collision exists — and if there is any doubt, such risk shall be deemed to exist. On the exam, 'I wasn't sure' always resolves to 'risk exists'.
Constant bearing
CBDR
Risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. Constant bearing, decreasing range is the textbook indication.
Radar duties
Long-range scanning and plotting
Where radar is fitted and operational, proper use includes long-range scanning for early warning and radar plotting or equivalent systematic observation of detected objects. Assumptions must not be made on scanty information, especially scanty radar information.
Rule 7 — common exam questions#
How do you determine whether risk of collision exists?
By using all available means appropriate to the prevailing circumstances and conditions — and if there is any doubt, the risk is deemed to exist (33 CFR §83.07(a)).
What is CBDR?
Constant bearing, decreasing range. Rule 7(d)(i) says risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change.
Can risk of collision exist even if 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 when approaching a vessel at close range.
Must radar be used if it is fitted?
Yes. Rule 7(b) requires proper use of radar equipment if fitted and operational, including long-range scanning and radar plotting or equivalent systematic observation.
Authoritative source#
- 33 CFR §83.07 — this section with its neighbours. 33 CFR Part 83 is public domain; checked 2026-05-16.
- COLREGs Rule 7 is published by the IMO and is authoritative internationally.
Practise this rule against the real exam.
Real exam questions. No signup, no card.
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