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Just limited underkeel clearance is not enough to consider a vessel as constrained by her draught

  • Description of scenario: Vessel A: Power-driven vessel underway (Dynamic draft 12 m)
    Vessel B: Power-driven vessel underway (Dynamic draft 5 m)
    Area: Open sea (Depth 14~15 m)
    Visibility: Good (Vessels are in sight of one another)
    Vessel A and vessel B are crossing so as to involve risk of collision
    Vessel A has vessel B on her own starboard side (relative bearing STBD 054°)
  • Rule(s) to be applied: Rule 15 Crossing situation
    Rule 16 (Action by give-way vessel)
    Rule 17 (Action by stand-on vessel)
  • 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 A) which has the other (vessel B) on her own starboard side shall keep out of the way.
    In accordance with Rule 15 (Crossing situation), vessel A shall, if the circumstances of the case admit, avoid crossing ahead of the vessel B.
    In accordance with Rule 16 (Action by give-way vessel), every vessel (vessel A) which is directed to keep out of the way of another vessel (vessel B) 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 A) the other (vessel B) shall keep her course and speed.

    Although vessel A navigates in an area with a small underkeel clearance but with adequate space to take avoiding action she should not be regarded as a vessel constrained by her draught and Rule 18 (Responsibilities between vessels) doesn’t apply. Limited underkeel clearance in not by itself enough to consider vessel A as constrained by her draught if the waterway provides ample manoeuvring room of the same depth on either side.

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