Module 5 - COLREGs
Rule 8 — Action to Avoid Collision
What you will learn
Choose and monitor collision-avoidance action that is lawful, early, positive, readily apparent and capable of producing a safe passing distance.
A manoeuvre is not successful because the helm moved. It succeeds only if it follows the applicable rule, is clear to the other vessel and is observed to create safe clearance without a new danger.
Rule 8 requires avoiding action to comply with the Rules of Part B and, when circumstances admit, to be positive, made in ample time and taken with due regard to good seamanship. Alterations of course or speed should be large enough to be readily apparent visually or by radar; avoid a succession of small ambiguous changes unless a larger change would produce greater danger.
With enough sea room, alteration of course alone can be the most effective action if it is made in good time, substantial and does not create a new close-quarters situation. The chosen manoeuvre must result in passing at a safe distance, and its effectiveness must be checked until the other vessel is finally past and clear.
Speed is also a control. When necessary to avoid collision or allow more time to assess, slacken speed, take all way off by stopping propulsion or reverse propulsion when appropriate to the vessel and conditions. This is not a rote instruction to stop in every encounter: sea room, following traffic, manoeuvrability, wind, current and the applicable give-way action still matter.
Worked example
A power-driven yacht is give-way in a crossing situation. The contact remains on a near-steady starboard-bow bearing with ample open water astern of it.
- 1Confirm the crossing situation, collision risk and absence of a conflicting overtaking, channel or TSS obligation.
- 2Make an early substantial alteration that passes well astern, rather than several small turns or an attempt to cross ahead.
- 3Retake bearings and check the wider traffic picture until the contact is finally past and clear before resuming the passage plan.
Sense check: The relative bearing should open convincingly and the new track should not point the yacht into another contact or navigational hazard.
Choose the complete manoeuvre
A large starboard alteration would avoid one vessel but place the yacht across a second contact's track.
1. Widen the picture
Check every relevant contact, depth and traffic constraint before committing the helm.
2. Use both controls
Consider a substantial lawful course change, a timely speed reduction or a combination that avoids both contacts.
3. Prove the result
Monitor bearings, range and the second contact until the whole situation is safe.
Sense check: Solving one CPA while creating a new close-quarters situation is not effective Rule 8 action.
Common mistake or limitation
- 'Alter to starboard' is not a universal Rule 8 answer; the encounter rule, sea room and surrounding traffic determine the safe action.
- Returning to the original course before the other vessel is finally past and clear can undo the passing distance just created.
Recap
- Early, positive and readily apparent action gives both vessels time to understand the developing situation.
- Course, speed or both can be used, but the manoeuvre must obey the applicable rule and preserve the wider traffic picture.
- Continue observing until the safe passing result is established, not merely until the first alteration is complete.
Optional quick check
Section 4 of 9
What completes a substantial early alteration made to avoid collision?
Continue studying COLREGs
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