Part B · Steering and sailing rules · Rule 17
Action by Stand-on Vessel
17(a) (i) Where one of two vessels is to keep out of the way the other shall keep her course and speed.
- “Where one of two vessels is to keep out of the way the other shall keep her course and speed”When another Rule makes one vessel the give-way vessel (Rules 12, 13, 15 or 18), the other is the stand-on vessel. She keeps her course and speed so the give-way vessel can predict where she will be and plan her action. Altering early would undermine the give-way vessel’s plan.
Stand-on vessel: hold your course and speed, and keep watching the give-way vessel.
17(a)(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 may however take action to avoid collision by her manoeuvre alone”“The latter vessel” is the stand-on vessel. She may act on her own, but at this stage it is optional: “may”, not “shall”.
- “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”This becomes apparent when the give-way vessel isn’t acting early and substantially as Rule 16 requires: the bearing isn’t changing and the range is closing. If in doubt about her intentions, sound at least five short and rapid blasts (Rule 34(d)). If you then manoeuvre, make it clear and sound the matching signal, for example one short blast for an alteration to starboard (Rule 34(a)).
If the give-way vessel isn’t doing her job, you may act, but you don’t have to yet. Sound five or more short blasts first if in doubt.
17(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.
- “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”Whatever the reason, the stand-on vessel is now so close that the give-way vessel can no longer avoid a collision by herself.
- “she shall take such action as will best aid to avoid collision”Now the stand-on vessel must act: “shall”, not “may”. She takes whatever action gives the best chance of avoiding collision.
Too close for the give-way vessel to avoid collision alone? The stand-on vessel must now act.
17(c) A power-driven vessel which takes action in a crossing situation in accordance with sub-paragraph (a)(ii) of this Rule to avoid collision with another power-driven vessel shall, if the circumstances of the case admit, not alter course to port for a vessel on her own port side.
- “A power-driven vessel which takes action in a crossing situation in accordance with sub-paragraph (a)(ii) of this Rule to avoid collision with another power-driven vessel”This applies to a power-driven stand-on vessel in a crossing situation (Rule 15) that decides to act under 17(a)(ii).
- “shall, if the circumstances of the case admit, not alter course to port for a vessel on her own port side”The give-way vessel is on her port side. Her most likely action is an alteration to starboard, so a turn to port by the stand-on vessel could turn both vessels towards each other. Unless the circumstances prevent it, don’t alter to port; alter to starboard or reduce speed instead.
Stand-on in a crossing and deciding to act? Don’t turn to port towards the vessel on your port side.
17(d) This Rule does not relieve the give-way vessel of her obligation to keep out of the way.
- “This Rule does not relieve the give-way vessel of her obligation to keep out of the way”Whatever the stand-on vessel does under (a)(ii) or (b), the give-way vessel still has to keep out of the way until she is past and clear.
The give-way vessel’s duty never transfers to the stand-on vessel.