Colregs Questions and Answers (Q & A)

Rule 8

Action to avoid collision

The answers can be found in the respective Rules and Paragraphs in the book"International Regulations for Preventing Collisions at Sea (Colregs) by Capt. Pierre Deseck and/or in the Colregs Presentation (on DVD), also by Capt. Pierre Deseck

Q = Question; A= Answer

Q 8-1
Discuss how action to avoid collision should be taken.

A 8-1
Rule 8 (a) and Par. 8.1, Positive action, in ample time, observing good seamanship.
Click on action to avoid collision for a summary


Q 8-2
In the case of question 8-1, what does good seamanship means ?

A 8-2
Par. 8.1, Positive action, in ample time, observing good seamanship, second paragraph.


Q 8-3
 What do you understand by “in ample time” ?

A 8-3
In most cases, when risk of collision exists, it is rather easy to determine HOW one should manoeuver. But, WHEN one should take action is a bit more complex and depends, to a large extend, on the existing cir­cumstances.

The size and speed of the vessels involved, the manoeuvring charac­teristics of the own vessel (turning circle, stopping distance), the type of activity the vessel is angaged in (towing, dredging, fishing, etc.), where on the horizon the stand-on vessel is spotted, the available water to ma­noeuvre (sea-room), the presence of hazards to navigation, the state of the sea and the weather conditions, etc. are some of the factors that should be considered.

Any action to avoid collision should rather be taken too early than too late. Especially on large and very large vessels who usually react much slower than smaller vessels.

In my carreer as an officer and master, I have often seen how young of­ficers hesitate in starting avoiding action for another vessel. I have seen ofiicers holding the chadburn for many minutes not knowing wheter to keep the vessel’s speed or to slow down.

Masters and senior officers should assist young watchkeeping officers in assessing how and WHEN to manoeuvre, so that they can solidify their confidence and soon take action on their own without having to compromise the safety of their own vessel and/or of other vessels


Q 8-4
 Before taking avoiding action, which points with regard to the stand-on or privileged vessel must be known ?

A 8-4
Par. 8.2, Substantial alterations of course and/or speed to be readily ap­parent, first paragraph.
Click on stand-on vessel for a summary


Q 8-5
 Why are small alterations of course to be avoided ?

A 8-5
Rule 8 (b) and Par. 8.2, Substantial alterations of course and/or speed to be readily apparent.


Q 8-6
 How large should an alteration of course be, to be readily apparent ?

A 8-6
Par. 8.2, Substantial alterations of course and/or speed to be readily ap­parent, seventh paragraph.
Click on readily apparent for a summary


Q 8-7
 How can you determine the course and speed of a vessel at night ?

A 8-7
Par. 8.2, Substantial alterations of course and/or speed to be readily apparent, third paragraph.


Q 8-8
 When are alterations of course more effective and when are alterations of speed more effective

A 8-8
Par. 8.2, Substantial alterations of course and/or speed to be readily apparent, ninth paragraph.


Q 8-9
 When should an alteration of course and of speed be made simultane­ously ?

A 8-9
Par. 8.2, Substantial alterations of course and/or speed to be readily apparent, tenth paragraph.


Q 8-10
 Which points shall you take into account to make an alteration of course alone in case of risk of collision ?

A 8-10
Rule 8 (c) and Par. 8.3, Alteration of course alone.
Click on alteration of course alone for a summary


Q 8-11
 Comment the content of Rule 8 (d): passing one another at a safe dis­tance.

A 8-11
Rule 8 (d) and Par. 8.4, Passing one another at a safe distance. con­sider also on interaction between vessels, yawing of the vessels, a sud­den sheer of one of the vessels, engine or rudder breakdown on one of the vessels, an unexpected danger, etc. The further apart vessels remain of each other, the smaller the risk of colliding will be.


Q 8-12
 Is it safe to pass astern of another vessel by steering a course on her stern ?

A 8-12
Par. 8.4, Passing one another at a safe distance, third paragraph.


Q 8-13
 When can you say that risk or danger of collision with a particular vessel is definitly passed ?

A 8-13
Par. 8.4, Passing one another at a safe distance, second paragraph.


Q 8-14
 How can you reduce or slacken a vessel’s speed ?

A 8-14
Par. 8.5, Slackening of speed, first paragraph.
Click on reduce speed for a summary


Q 8-15
 Which factors must you take into account when you want to stop the vessel by reversing her means of propulsion ?

A 8-15
Par. 8.5, Slackening of speed, second paragraph


Q 8-16
 Define the terms stopping distance and stopping time.

A 8-16
Par. 8.5, Slackening of speed, first paragraph, fourth and fifth para­graph.


Q 8-17
 What is the influence of the frictional resistance on a vessl’s hull on the stopping time ?

A 8-17
Par. 8.5, Slackening of speed, first paragraph, fourth and fifth para­graph, sixth paragraph.


Q 8-18
 What influence will reversing the means of propulsion of a vessel have (e.g. in a crash stop) on the vessel’s heading ?

A 8-18
Par. 8.5, Slackening of speed, first paragraph, elevent and twelfth par­agraph.


Q 8-19
 How can you notice the effectiveness of an alteration of speed ?

A 8-19
Par. 8.5, Slackening of speed, first paragraph, ninth paragraph.


Q 8-20
 How can the rudder help you to stop your vessel even quicker ?

A 8-20
Par. 8.5, Slackening of speed, first paragraph, seventh paragraph.


Q 8-21
 How can you increase the time to assess what action to take when there is a risk of collision ?

A 8-21
Rule 8 (e).
Click on assess action for a summary


Q 8-22
 What are the advantages of reducing a vessel’s speed or even bringing her to rest if there is a risk of collision ?

A 8-22
Par. 8.5, Slackening of speed, first paragraph, fourtheenth paragraph.
Click on reducing speed for a summary


Q 8-23
 In which cases is it imperative to reduce speed or even to bring the ves­sel to rest ?

A 8-23
Par. 8.5, Slackening of speed, first paragraph, fiteenth paragraph.
Click on bring the vessel at rest for a summary


Q 8-24
 Comment what you understand by “not to impede the safe passage of another vessel”.

A 8-24
Rule 8 (f) and Par. 8.6, Not to impede the passage of another vessel.
Click on not to impede for a summary


Q 8-25
 Is a vessel who’s safe passage must not be impeded, fully privileged when risk of collision exist ?

A 8-25
Rule 8 (f) (iii) and Par. 8.6, Not to impede the passage of another ves­sel.
Click on safe passage for a summary


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