Relevant documents and M-notices: MGN 1781
Rules 16 and 17 are extremely important to how we answer rules of the road questions; that is, to the order in which we give our answer. This is especially true of Rule 17. Once you’ve read and understood this article, re-read the linked article on wording your answers to help get these sequences, and phrases, stuck in your head.
Rule 16 - Action by give-way vessel
Part of the title of this rule - give-way vessel - is the first time that phrase occurs in the rules. The body of the rule indirectly defines the give-way vessel, as ‘Every vessel which is directed to keep out of the way of another vessel’. This is extremely important, as ‘give-way vessel’ is a phrase that is used a lot in the teaching and learning of these rules; you should know where it comes from and what it means.
Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear.
Every vessel which is directed to keep out of the way of another vessel shall
Various rules direct one vessel to keep out of the way of another; see Rules 12, 13, 15 and 18. Then we have that word shall, which means you have an obligation to…
so far as possible, take early and substantial action to keep well clear.
This is largely re-iterating Rule 8 - Action to avoid collision. Rule 8 (b) and (c) state that:
Any alteration of course and/or speed to avoid collision shall, if the circumstances of the case admit, be large enough to be readily apparent to another vessel observing visually or by radar; a succession of small alterations of course and/or speed should be avoided.
If there is sufficient sea-room, alteration of course alone may be the most effective action to avoid a close-quarters situation provided that it is made in good time, is substantial and does not result in another close-quarters situation.
Rule 17 -Action by the stand-on vessel
There is a bit more to Rule 17 than there is to Rule 16. Rule 17 is extremely important to the order that we take action as the stand-on vessel.
(a) (i) Where one of two vessels is to keep out of the way the other shall keep her course and speed.
So, the give-way vessel (as per Rule 16) has to take early and substantial action to keep well clear, meaning that the stand-on vessel can keep her course and speed. Think of this as your initial obligation of the stand-on vessel. Even though you’re not changing course or speed, this is still an action; it’s a conscious decision that you make when following the rules. When asked ‘what action would you take?’ do not say ‘I would not take action’ or ‘I would do nothing, I am the stand-on vessel’. The phrase to use is:
‘I would stand-on with caution and continue to monitor. I would consider putting a man on the wheel.’
(ii) The latter vessel may however take action to avoid collision by her manoeuvre alone, as soon as it becomes apparent to her that the vessel required to keep out of the way is not taking appropriate action in compliance with these Rules.
The latter vessel, in this case, is the stand-on vessel.
May means that, though you do not have an obligation to do so, you have the option of doing so.
take action to avoid collision by her manoeuvre alone
This action to avoid collision must meet the requirements of Rule 8, and must be sufficient that, even if the give-way vessel takes no action, there will be no collision.
as soon as it becomes apparent to her that the vessel required to keep out of the way is not taking appropriate action in compliance with these Rules.
Appropriate action is action that meets the requirements of Rule 8, from the point-of-view of the stand-on vessel (apparent to her). So a change in speed or an alteration of course that does not seem, to the stand-on vessel, to meet the requirements of Rule 8 (or if there is no alteration of course and/or speed at all) means that the stand-on vessel may take action under this sub-paragraph.
What else must you do at this point? Quickly check Rule 34 (d), and note that it says shall.
Does altering course/speed under Rule 17 make you the give-way vessel?
No, it does not. You are taking action as the stand-on vessel. If the goalkeeper kicks the ball the length of the pitch and scores a goal, does that make him the striker? No; he took action as the goalkeeper to score a goal. Remember that the goalkeeper’s shirt doesn’t magically change if they manage to score a goal.
(b) When, from any cause, the vessel required to keep her course and speed finds herself so close that collision cannot be avoided by the action of the give-way vessel alone, she shall take such action as will best aid to avoid collision.
Perhaps an inadequate lookout has been kept, or the rudder has mysteriously failed to follow commands up till now, or the OOW briefly lost consciousness for some unknown medical reason; if from any cause the stand-on vessel finds herself so close that collision cannot be avoided by the action of the give-way vessel alone, she shall…
Again, that shall means there is an obligation. The rest of this sentence explains well when Rule 17 (a) (ii) ends and Rule 17 (b) begins; the moment that a collision cannot be avoided by the action of the give-way vessel alone, the stand-on vessel shall take action under Rule 17 (b). How can we know for certain when this is the case? We don’t know the manoeuvring characteristics of the other vessel, so we have to use our best judgement.
take such action as will best aid to avoid collision.