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Multi-ship encounter situation on the high seas in restricted visibility

  • Description of scenario: Vessel A: Power-driven vessel
    Vessel B: Power-driven vessel
    Vessel C: Power-driven vessel
    Vessel D: Power-driven vessel
    Vessel E: Power-driven vessel
    Area: On the high seas
    Visibility: Restricted (All vessels not in sight of one another)
    Vessel E is doing same course and speed as vessel A
    Vessels A, B, C and D are sailing so to involve risk of collision between each of them
    Vessel A has vessel B on her own starboard side (relative bearing STBD 100°)
  • Rule(s) to be applied: Rule 2 (Responsibility)
    Rule 19 (Conduct of vessels in restricted visibility )
  • Applying the Rule(s) and comments: Crossing situation (vessels A, B, C and D):
    In accordance with Rule 19 (d)(ii) (Conduct of vessels in restricted visibility ), vessel A shall so far as possible avoid an alteration of course towards a vessel abeam or abaft the beam, so she should alter her course to port for vessel B.
    In accordance with Rule 8 (e) (Action to avoid collision ) if necessary to avoid collision vessel A shall slacken her speed.
    In accordance with Rule 19 (d)(i) (Conduct of vessels in restricted visibility ), vessel A shall so far as possible, avoid an alteration of course to port for vessels C and D because they are forward of her beam. Therefore vessel A should alter her course to starboard for Vessel C and D.
    In accordance with Rule 19 (d)(i) (Conduct of vessels in restricted visibility ), vessel B shall so far as possible, avoid an alteration of course to port for vessels A, C and D because they are forward of her beam. Therefore vessel B should alter her course to starboard for vessel A, C and D.
    In accordance with Rule 19 (d)(i) (Conduct of vessels in restricted visibility ), vessel C shall so far as possible, avoid an alteration of course to port for vessels A, B and D because they are forward of her beam. Therefore vessel C should alter her course to starboard for vessel A, B and D.
    In accordance with Rule 19 (d)(i) (Conduct of vessels in restricted visibility ), vessel D shall so far as possible, avoid an alteration of course to port for vessels A, B and C because they are forward of her beam. Therefore vessel D should alter her course to starboard for vessel A, B and C.

    Comments:
    Vessel E is doing same course and speed as vessel A. Vessel E is also in crossing situation with vessels B, C and D but between vessel E and all other vessels (A, B, C, D) there is no risk of collision.
    All vessels are navigating in restricted visibility and sounding their prescribed sound signals of one prolonged blast at intervals not exceeding two minutes.
    All vessels cannot sound manoeuvring and warning signals as laid down in Rule 34 as they are not in sight of one another.
    As all vessels are navigating in restricted visibility , there is no stand-on vessel. All vessels are obliged to give way to each other.
    Vessel A has obligation to alter her course to starboard to avoid collision with vessel C and D but this is not allowed to avoid collision with vessel B. Vessel A cannot even alter her course to port as vessel E is doing the same course and speed and there is not sufficient sea room for vessel A to come to port and pass astern of vessel E.
    Vessels B, C and D have in accordance with the Rules obligation to alter their course to starboard to avoid collision.
  • Actions: Vessels A, B, C and D can take following actions to avoid collision or close-quarters situation.

    a) Vessel A can slacken her speed and vessels B, C and D can alter their courses to starboard.

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    b) Vessel A could make early 360° turn to starboard, even though Rule 19 says she should so far as possible avoid altering towards a vessel abeam or abaft her beam. This is a case where Rule 2 (make a departure from these Rules to avoid immediate danger) and Rule 8 (made in ample time with due regard to the observance of good seamanship) can be seen.

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    c) Vessel A can keep her course and speed because she observes that vessels B, C and D took early action and altered their course to starboard before vessel A starts any avoiding action. In that case vessel A determines that there is no more risk of collision or close quarters situation developing. Keeping course and speed for vessel A in this case is probably the least dangerous option as it does not require her to alter her course towards another vessel or slow down.

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