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Multi-ship encounter situation on the high seas close to the area of restricted visibility

  • Description of scenario: Vessel A: Power-driven vessel
    Vessel B: Power-driven vessel
    Vessel C: Power-driven vessel
    Area: On the high seas
    Visibility: Restricted (Vessel C could not be observed from vessels A and B)
    Vessel A is navigating near an area of restricted visibility its starboard side
    Vessel A is sounding one prolonged blast at intervals not exceeding two minutes
    Vessel A and vessel B are crossing so as to involve risk of collision and are in sight of one another
    Vessel A has vessel B on her own port side (relative bearing PORT 060°)
    Vessel C is not in sight of vessels A or B and is in the area of restricted visibility
    Vessel C is sounding one prolonged blast at intervals not exceeding two minutes
    Vessel A and C are crossing so as to involve risk of collision
    Vessel A has vessel C on her own starboard side (relative bearing STBD 040°)
    There is no risk of collision between vessels B and C
  • Rule(s) to be applied: Rule 15 (Crossing situation)
    Rule 16 (Action by give-way vessel)
    Rule 17 (Action by stand-on vessel)
    Rule 19 (Conduct of vessels in restricted visibility )
  • Applying the Rule(s) and comments: Crossing situation (vessel A and vessel B):
    In accordance with Rule 15 (Crossing situation), when two power-driven vessels are crossing so as to involve risk of collision, the vessel (vessel B) which has the other (vessel A) on her own starboard side shall keep out of the way.
    In accordance with Rule 15 (Crossing situation), vessel B shall, if the circumstances of the case admit, avoid crossing ahead of vessel A.
    In accordance with Rule 16 (Action by give-way vessel), every vessel (vessel B) which is directed to keep out of the way of another vessel (vessel A) shall, so far as possible, take early and substantial action to keep well clear.
    In accordance with Rule 17 (a)(i) (Action by stand-on vessel), where one of two vessels is to keep out of the way (vessel B) the other (vessel A) shall keep her course and speed.

    Crossing situation (vessel A and vessel C):
    Vessel A and vessel C are not in sight of one another, therefore as a risk of collision and/or close quarter situation is developing, Rule 19 (Conduct of vessels in restricted visibility ) apply.
    In accordance with Rule 19 (d)(i) (Conduct of vessels in restricted visibility ), vessel A should avoid an alteration of course to port for a vessel forward of her beam. Vessel A should therefore alter course to starboard (or slow down in accordance with Rule 19 (c) and Rule 8 ).
    In accordance with Rule 19 (d)(i) (Conduct of vessels in restricted visibility ), vessel C should avoid an alteration of course to port for a vessel forward of her beam. Vessel C should therefore alter course to starboard (or slow down in accordance with Rule 19 (c) and Rule 8 ).

    Comments:
    Vessel A is navigating near an area of restricted visibility and sounding her prescribed sound signal of one prolonged blast at intervals not exceeding two minutes.
    Vessel C is in the area of restricted visibility and she also sound one prolonged blast at intervals not exceeding two minutes.
    Vessel B is navigating in clear visibility and is in sight of vessel A. She has detected by radar vessel C and determined in accordance with Rule 7 (Risk of collision) that there is no risk of collision or close quarter situation developing with vessel C.
    As there is a risk of collision between vessel A and vessel B and both vessels are in sight of one another, vessel A should maintain her course and speed in accordance with Rule 17 (a)(i) (Action by stand-on vessel), and vessel B is directed to keep out of the way of vessel A in accordance with Rule 16 (Action by give-way vessel).
    Vessel A should maintain her course and speed for vessel B but vessel A is in the same time obliged to avoid collision with vessel C. In accordance with Rule 19 (Conduct of vessel in restricted visibility ), vessel A and vessel C must give way to each other and should not alter course to port for a vessel forward of the beam (unless they are overtaking it). Therefore vessel A should alter her course to starboard or slow down for vessel C.
  • Actions: Vessels A, B and C can take following actions to avoid collision or close-quarters situation.

    a) All vessels should alter their course to starboard in accordance with Rule 15 and Rule 19 even such action takes vessel A into the fog bank.

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    b) Vessels B and C should alter their course to starboard in accordance with Rule 15 and Rule 19 . Vessel A could slow down to allow vessel C to pass, but this might embarrass vessel B who has to give way to vessel A in accordance with Rule 15. If vessel A for some special circumstances could not alter her course to starboard but slow down to avoid collision with vessel C she could give manoeuvring and warning signals to vessel B because vessels A and B are in sight of one another.

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