6.3 Steering Rules: Sailing Vessels, Overtaking, Head-on & Crossing (Rules 12-17)

6.3 Steering Rules: Sailing Vessels, Overtaking, Head-on & Crossing (Rules 12-17)

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Rule 12: Sailing Vessels Encountering Sailing Vessels

When two sailing vessels are approaching one another so as to involve risk of collision, Rule 12 dictates who must keep clear according to wind orientation:

1. Wind on Different Sides (Rule 12(a)(i))

"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."

• Starboard Tack vs. Port Tack: A vessel on starboard tack (wind blowing across her starboard deck, with the mainsail out to port) is the stand-on vessel.
• A vessel on port tack (wind blowing across her port side, with the mainsail out to starboard) is the give-way vessel and must keep clear.
• Seamanship Mnemonic: "Port gives way to Starboard."

2. Wind on the Same Side (Rule 12(a)(ii))

"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 two sailing yachts are both sailing on a starboard tack (or both on a port tack), the windward vessel (upwind) must keep clear of the leeward vessel (downwind).
• Rationale: The leeward vessel is in the wind-shadow of the upwind vessel and has less tactical manoeuvring freedom.

3. Uncertainty on Port Tack (Rule 12(a)(iii))

"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."

Determining the Windward Side (Rule 12(b))

The windward side is deemed to be the side opposite to that on which the mainsail is carried (or in square-rigged vessels, opposite the largest fore-and-aft sail). When goose-winging downwind, check the mainsail boom position.

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Rule 13: Overtaking

Rule 13 is the trump card of the collision regulations: "Notwithstanding anything contained in the Rules of Part B, Sections I and II, any vessel overtaking any other shall keep out of the way of the vessel being overtaken."

Definition of Overtaking

A vessel is overtaking when coming up with another vessel from a direction more than 22.5° abaft her beam (an arc of 135° centred on the stern):

• At night, an overtaking vessel can see only the sternlight of the vessel being overtaken, and neither of her sidelights.
• By day, if a skipper is in doubt as to whether they are abaft this 22.5° line, they must assume they are overtaking and keep clear.

The "Once Overtaking, Always Overtaking" Rule (Rule 13(d))

"No subsequent alteration of the bearing between the two vessels shall make the overtaking vessel a crossing vessel within the meaning of these Rules, or relieve her of her duty of keeping clear of the overtaken vessel until she is finally past and clear."

Even if an overtaking vessel draws abeam and sees the green sidelight of the overtaken ship, she does not convert into a stand-on crossing vessel under Rule 15. She remains burdened under Rule 13 until completely past and clear. Rule 8(f) also preserves an applicable duty not to impede: for example, a small yacht must not obstruct a channel-bound ship, while the ship must keep clear if overtaking.

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Rule 14: Head-on Situation

Rule 14 applies when two power-driven vessels meet on reciprocal or nearly reciprocal courses so as to involve risk of collision:

• Visual Identification: By day, seeing the masts in line. At night, seeing both sidelights (red and green) and/or the masthead lights in line.
• Mandatory Action: Each vessel shall alter her course to starboard so that each passes on the port side of the other (port-to-port passing).
• In Case of Doubt: If a power-driven vessel cannot determine with certainty whether a head-on situation exists, she must assume it exists and turn to starboard.

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Rule 15: Crossing Situation

When two power-driven vessels are crossing so as to involve risk of collision:

• The vessel that has the other on her own starboard side is the give-way vessel.
• The give-way vessel shall, if circumstances admit, avoid crossing ahead of the other.
• Practical Action: Turn to starboard and pass astern of the stand-on vessel. At night, seeing another vessel's red sidelight on your starboard bow means: Red on your starboard, give way and pass behind her!

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Rules 16 & 17: Give-Way and Stand-On Protocols

Rule 16: Action by Give-Way Vessel

Every vessel directed to keep out of the way shall, so far as possible, take early and substantial action to keep well clear.

Rule 17: Action by Stand-On Vessel (The Three Stages)

Rule 17 imposes a carefully calibrated legal sequence to ensure predictability while avoiding collisions:

1. Stage 1 (Rule 17(a)(i)): The stand-on vessel SHALL maintain her course and speed. This provides predictability so the give-way vessel can execute her manoeuvre.
2. Stage 2 (Rule 17(a)(ii)): If the give-way vessel fails to act, the stand-on vessel MAY take action to avoid collision by her manoeuvre alone, as soon as it becomes apparent that the give-way vessel is not taking appropriate action (sounding 5 short warning blasts).
3. Stage 3 (Rule 17(b)): When collision cannot be avoided by the give-way vessel alone, the stand-on vessel SHALL take such action as will best aid to avoid collision.

Rule 17(c): The Prohibition on Altering to Port

"A power-driven vessel which takes action in a crossing situation in accordance with subparagraph (a)(ii) 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."