Risk of Collision

Rule text#

(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.

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.

Authoritative source#

Source links checked against the current public rule corpus on 2026-05-16.

• 33 CFR §83.07 — the section this text comes from, with its neighbours.
• The Inland Navigation Rules are codified at 33 CFR Part 83 and are public domain. The international COLREGs text is published separately by the IMO.

Practice this rule#

One real exam question on this rule, cited to source. No sign-up.