Module 5 - COLREGs
Rule 7 — Risk of Collision
Rule 7: quick answer
COLREG Rule 7 requires every available means appropriate to the circumstances to assess collision risk; if in doubt, assume it exists. Use a sequence of bearings and ranges, and proper radar observation when available. A steady bearing with decreasing range is a warning, but an appreciable bearing change does not always prove safety.
- Avoid conclusions from one bearing, one CPA value or scant radar data.
- AIS supplements rather than replaces lookout and risk assessment.
- Confirm the trend early enough for clear Rule 8 action.
Active recall
Section 3 of 9
Explain the main idea from rule 7 — Risk of Collision in your own words.
You must use all available means to determine if a risk of collision exists. If there is any doubt, assume it does exist.
The most reliable technique is compass bearings: if the bearing of an approaching vessel does not change appreciably, a risk of collision exists. This is called a 'constant bearing, decreasing range' (CBDR) situation.
Common mistakes
- Treating a changing bearing as automatic proof that the contact will pass clear.
- Using AIS CPA as the sole collision-risk verdict.
- Starting systematic observations too late for early action.
Tip: Take a series of compass bearings on an approaching vessel. If the bearing stays roughly the same but the vessel is getting closer, you are on a collision course.
Key points
- If in doubt, risk of collision EXISTS
- Constant bearing + decreasing range = collision risk
- Use compass bearings to assess risk
Apply Rule 7 to complete encounters
The COLREGs module links lookout, safe speed, risk assessment, avoiding action and vessel responsibilities.