Preventing Collisions: Construing & Complying, Rule 8(f), “Not to Impede”

NL 42 Preventing Collisions: Construing & Complying,
Rule 8(f), “Not to Impede”


Capt Chhabra

Capt. Yashwant Chhabra
Author: ‘A Mariners Guide to Preventing Collisions’,
Fellow: The Company of Master Mariners of India,
Associate Fellow: Nautical Institute.
Working as: Senior Manager, Training & Development, MSI Ship
Management Pte Ltd Singapore.


This is in continuation of my previous paper on the subject of preventing collisions published in newsletter 26 of October 2013, I had then shown some of the weak areas about the misunderstandings and incorrect application of the rules with reasons. Since then, as much as I know, the spate of collisions has not reduced and they continue at regular intervals. The usual list of root causes that it was sheer bad luck, poor look out, loss of situational awareness and even inappropriate use or misuse of VHF etc., are perhaps not the real root causes. A prudent watch keeper needs to be fully dedicated and devoted to the task of navigation as the 1st priority, but the execution of the tasks should be built on a solid foundation of knowledge, understanding and core fundamentals so that the concepts are clear for best practical application. The application of the Rules has to be in conjunction with watchkeeping standards from STCW Convention Sections VIII/2, SOLAS Chapter V, basic ship handling elements and any requirements incorporated in the Safety Management System of a Company, the last being mandatory under the ISM Code.

A reputed Hull and Machinery underwriter recently commented, there seems to be no change in the claim trend of maritime collisions pre ISM to post ISM, in effect the benefits of the ISM Code can again be debated, but this article is not on this. As stated by me earlier, the construing element of the rules needs to be addressed first and then better compliance or practical application can be expected.

This article is to explain paragraph ‘f’ of Rule 8, this paragraph was added to these Rules of 1972 in 1989 primarily to clarify the application of ‘shall not impede’ and thus making MSC/Circ.320 of 05.04.1982, ‘Guidance for the Uniform Application of Certain Rules of the International Regulations for Preventing Collisions at Sea, 1972’ redundant as far as it explained the requirements on ‘not to impede’. Its placement and cross linkages with other rules makes its understanding and application a little complex.

(i)‘A vessel which, by any of these Rules, is required not to impede the passage or safe passage of another vessel shall, when required by the circumstances of the case, take early action to allow sufficient sea room for the safe passage of the other vessel’.

(ii)‘A vessel required not to impede the passage or safe passage of another vessel is not relieved of this obligation if approaching the other vessel so as to involve risk of collision and shall, when taking action, have full regard to the action which may be required by the Rules of this part’.

(iii)‘A vessel the passage of which is not to be impeded remains fully obliged to comply with the Rules of this part when the two vessels are approaching one another so as to involve risk of collision’.

When is this rule applicable? This is the 1st question. The Answer lies in subparagraph ‘f-i’ of this Rule itself, ‘a vessel which, by any of these Rules, is required not to impede the passage or safe passage of another vessel’. ‘Not impede’ and similar terms using ‘impede’ are used in Rules 9 (b), (c), (d), 10 (i), (j), 18 (d-i), (e) and (f-i) of this Part ‘B’. As per any of these, when ‘not to impede’ is activated, its application is in conjunction with and by complying with the requirements of Rule 8(f). Thus Rule 8(f) applies only with these 8 referred paragraphs of the Rules and not with any other, for example Rule 8(f) has nothing to do with the application of say Rule 15 ‘crossing situation’.

This Rule is placed in section ‘I’ of Part ‘B’ and shall ‘apply in any condition of visibility’, the latter clause equally applies to Rules 9 and 10. However, when applied with Rule 18, this Rule will only ‘apply to vessels in sight of one another’ as Rule 18 is in section ‘II’ of Part ‘B’.

For vessels ‘in sight of one another’, ‘not to impede’ takes precedence over ‘give-way’ as will be the first obligation whenever required, ‘keep her course and speed’ will not apply with this rule ever as explained further.

As a quick reference the following chart should explain the basic application of this Rule.

2015-02-05 17.34.40_resized

Actually subparagraphs ii and iii get activated together. There is nothing like a stand-on vessel but when in sight of each other and in situations governed by subparagraphs ii and iii, restrictions imposed by Rule 17 would apply.

Each subparagraph is discussed individually.

‘i’ clearly places the obligation to keep clear on a vessel which is required by any of these Rules, as listed above, ‘not to impede the passage or safe passage of another vessel’. She ‘shall’ take ‘early action to allow sufficient sea-room for the safe passage of the other vessel’. ‘Sufficient’ like many other requirements of these Rules is not defined numerically and would need to be determined or judged using ‘ordinary practice of seamen’.

A vessel required ‘not to impede’ is obliged to ‘take early action’ to not allow any ‘risk of collision’ or ‘a close-quarters situation’ from developing, this may be done even before ‘determining if risk of collision exists’. The Rules does not prescribe any action so this vessel has freedom of choice in deciding ‘any alteration of course and/or speed’. Not allow any ‘risk of collision’ is derived from subparagraphs ‘ii’ and ‘iii’ which get activated only when the situation is leading ‘to involve risk of collision’.

‘When required by the circumstances of the case’ clause highlights situations not only where such action is required but also provides an escape clause, like many other similar escape clauses in these Rules, when circumstances may not allow ‘early action’ and/or the desired quantum of action.  For example, a small vessel is not able to observe from a reasonable distance away the day signals of a ‘vessel constrained by her draught’ in a ‘narrow channel’ and because of this does not take action in ‘ample’ or ‘good time’. This clause may also be applied when ‘restricted visibility’ conditions impose any restrictions.

‘ii’ Requires that a vessel required ‘not to impede’ continues to retain her obligation to ‘keep well clear’ in case an encounter with another vessel is leading ‘to involve risk of collision’.

‘Have full regard to the action which may be required by the Rules of this part’ means normal ‘action to avoid collision’ required by any of the Rules of this Part B, that is Rules 4 to19. If ‘risk of collision’ develops ‘a vessel’‘required not to impede’ should take into account the expected normal ‘action to avoid collision’ by both the vessels involved in the situation and should act in conformity with the same. Or, if she is a ‘stand-on vessel’ in the situation, then irrespective of what any other Rules may otherwise prescribe, this vessel cannot ‘keep her course and speed’ when she is required ‘not to impede’. Her actions, in line with the Rules of Part ‘B’ should be such as not to hinder or embarrass the action(s) expected of the other vessel which is also now obliged to act as per subparagraph ‘iii’ of this Rule.

‘iii’ Initially a vessel ‘whose passage is not to be impeded’, as implied by subparagraph ‘i’  ‘shall keep her course and speed’ to stay on her ‘passage’ or ‘safe passage’. She should keep a good watch on the vessel which is ‘required not to impede’, to monitor her actions.

This subparagraph, like subparagraph ‘ii’, applies as soon as it appears that the ‘a vessel required not to impede’ is not taking appropriate action in good time to keep clear and ‘a close-quarters’ and/or ‘risk of collision’ begins to develop. Now the vessel ‘not to be impeded’ should also take ‘action to avoid collision’ and ‘remains fully obliged to comply with the Rules of this part’. ‘This part’ means Rules of Part B.

When read in conjunction with the previous subparagraph 8(f)(ii), both, a vessel ‘required not to impede’ as well as the vessel ‘not to be impeded’, are obliged to and expected to execute ‘action to avoid collision’ if they reach a situation which may involve ‘risk of collision’. Their actions should be in compliance with the Rules of Part ‘B’, but both shall ‘take action’ even if ‘in sight of one another’, and both must comply with the requirements of Rule 19 when ‘not in sight of one another when navigating in or near an area of restricted visibility’.

The application of subparagraphs ‘ii’ and ‘iii’ is to avoid any conflicting actions which may further jeopardize the situation or can be considered taking actions ‘with due regard to the observance of good seamanship’.

Having explained the rule, I will leave it to the readers to work out various situations and how this rule should be correctly applied to the same.


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