RULE 11: Application
Rules in this section apply to all vessels in sight of one another.

RULE 12: Sailing vessels

1. When two sailing vessels are approaching one another, so as to involve risk of collision. One of them shall keep out of the way of the other as follow:
   • when each has the wind on a different side, the vessel which has the wind on the port side shall keep out of the way of the other.
   • when both have the wind on the same side, the vessel which is to windward shall keep out of the way of the vessel which is to leeward.
   • if a vessel with the wind on the port side sees a vessel to windward and cannot determine with certainty whether the other vessel has the wind on the port or on the starboard side, she shall keep out of the way of the other.
2. For the purposes of this rule the windward side shall be deemed to be the side opposite to that which the mainsail is carried or, in the case of a square-rigged vessel, the side opposite that on which the largest fore-and-aft sail is carried.

RULE 13: Overtaking

1. Notwithstanding anything contained in the rules of Part B, Section I and II, any vessel overtaking any other shall keep out of the way of the vessel being overtaken.
2. A vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22½° abaft her beam, that is, in such a position with reference to the vessel she is overtaking, that at night she would be able to see only the stern light of that vessel but neither of her side lights.
3. When a vessel is in any doubt as to whether she is overtaking another, she shall assume this is the case and act accordingly.
4. Any subsequent alteration of the bearing between the two vessels, shall not make the overtaking vessel a crossing vessel within the meaning of these rules or relieve her of the duty of keeping clear of the overtaken vessel until she finally past and clear.

RULE 14: Head–on Situation

1. When two power driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision each shall alter her course to starboard so that each shall pass on the port side of the other.
2. Such a situation shall be deemed to exist when a vessel sees the other ahead or nearly ahead and by night she could see the masthead lights of the other in line or nearly in line and /or both side lights and by day she observes the corresponding aspect of the other vessel.
3. When a vessel is in any doubt as to whether such a situation exists she shall assume that it does exist and act accordingly.

RULE 15: Crossing Situation
When two power driven vessels are crossing so as to involve risk of collision, the vessel which has
the other on her own starboard side shall keep out of the way and shall, if the circumstances of the case admit, avoid crossing ahead of the other vessel.

RULE 16: Action by Give-way vessel
Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear.

RULE 17: Action by Stand-on vessel

1. Stand-on vessel.
   • Where one of two vessels is to keep out of the way of the other shall keep her course and speed.
   • The latter vessel may however take action to avoid collision by her manoeuvre alone, as soon as it becomes apparent that the vessel required to keep out of the way is not taking appropriate action in compliance with these rules.
2. When, from any cause, the vessel required to keep 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.
3. A power driven vessel which takes action in a crossing manoeuvre in accordance with subparagraph (1) (second point) 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.
4. This rule does not relieve the give-way vessel of her obligation to keep out of the way.

RULE 18: Responsibilities between vessels.
Except where rule 9, 10 and 13 otherwise require.

1. A power driven vessel under way shall keep out of the way of:
   • a vessel not under command;
   • a vessel restricted in her ability to manoeuvre;
   • a vessel engaged in fishing;
   • a sailing vessel.
2. A sailing vessel underway shall keep out of the way of:
   • a vessel not under command;
   • a vessel restricted in her ability to manoeuvre;
   • a vessel engaged in fishing;
3. A vessel engaged in fishing shall keep out of the way of:
   • a vessel not under command;
   • a vessel restricted in her ability to manoeuvre;
4. vessel constrained by her draught.
   • any vessel other than a vessel not under command and a vessel restricted in her ability to manoeuvre shall, if the circumstances of the case admit, avoid impeding the safe passage of a vessel constrained by her draught, exhibiting the signals in rule 28.
   • a vessel constrained by her draught shall navigate with particular caution having full regard to her special condition.
5. A seaplane on the water shall in general, keep clear of all vessels and avoid impeding their navigation. In circumstances, however, where risk of collision exists, she shall comply with the rules of this part.
6. WIG craft.
   • A WIG craft shall, when taking off, landing and in flight near the surface, keep well clear of all other vessels and avoid impeding their navigation.
   • A WIG craft operating on the water surface shall comply with rules of this part as a power driven vessel.