Question 1

When may the stand-on vessel take action to avoid collision by her own manoeuvre alone?

Accepted Answer

When it becomes apparent that the give-way vessel is not taking sufficient avoiding action. Rule 17(a)(ii): the stand-on vessel MAY take action to avoid collision by her own manoeuvre alone as soon as it becomes apparent that the vessel required to keep out of the way is not taking appropriate action. Rule 17(b): when collision cannot be avoided by the give-way vessel alone, the stand-on vessel SHALL take the best action to avoid collision. Rule 17(c): action to port for a vessel on port side should be avoided.

Question 2

Rule 17(c) states that the stand-on vessel shall not alter course to port in certain circumstances. When?

Accepted Answer

For a vessel on her own port side, in a crossing situation. Rule 17(c): a power-driven vessel which takes action in a crossing situation in accordance with Rule 17(a)(ii) shall, if the circumstances of the case admit, not alter course to port for a vessel on her own port side. Altering to port toward a vessel already on the port side could worsen the situation. Altering to starboard (away) or slowing is preferable.

Question 3

The stand-on vessel in a crossing situation has been maintaining course and speed. The give-way vessel has not acted. The vessels are now 0.5nm apart with a CPA of zero. What should the stand-on vessel do?

Accepted Answer

Assess whether the give-way vessel can still avoid collision; she may act when its failure to act appropriately is apparent and must act when its action alone cannot avoid collision.. Rule 17(a)(i) initially requires the stand-on vessel to maintain course and speed. Under Rule 17(a)(ii), she may take avoiding action by her manoeuvre alone as soon as it becomes apparent that the give-way vessel is not taking appropriate action. Under Rule 17(b), she must take such action as will best aid avoidance of collision when she finds herself so close that collision cannot be avoided by the give-way vessel's action alone. A separation of 0.5 nm and zero CPA do not by themselves establish that threshold; speeds, manoeuvrability and other circumstances matter. Rule 17(c) applies to a power-driven vessel taking action under Rule 17(a)(ii) in a crossing situation with another power-driven vessel: if the circumstances admit, she shall not alter course to port for a vessel on her own port side. It is not an outright prohibition governing action under Rule 17(b). If in doubt about the other vessel's intentions or whether sufficient action is being taken, a vessel in sight of the other must sound at least five short and rapid blasts under Rule 34(d), without delaying necessary avoiding action. The give-way vessel remains obliged to keep out of the way.

Rule 17, questions and explanations

When may the stand-on vessel take action to avoid collision by her own manoeuvre alone?

Rule 17(c) states that the stand-on vessel shall not alter course to port in certain circumstances. When?

The stand-on vessel in a crossing situation has been maintaining course and speed. The give-way vessel has not acted. The vessels are now 0.5nm apart with a CPA of zero. What should the stand-on vessel do?

Practise this properly

Rule 17, questions and explanations

Questions

When may the stand-on vessel take action to avoid collision by her own manoeuvre alone?

Rule 17(c) states that the stand-on vessel shall not alter course to port in certain circumstances. When?

The stand-on vessel in a crossing situation has been maintaining course and speed. The give-way vessel has not acted. The vessels are now 0.5nm apart with a CPA of zero. What should the stand-on vessel do?

Practise this properly