1.7 Overtaking (Rules 11-13)

Rule 11 — Application of the In-Sight Rules

Rule 11 is a single sentence that governs the entire block of steering rules 12 through 18: "Rules in this section apply to vessels in sight of one another." This is a crucial gate. The familiar give-way/stand-on, head-on, crossing, and overtaking rules only operate when the two vessels can see each other visually. If you detect a vessel only by radar in fog, you are not in a crossing or overtaking situation — you are in restricted visibility, and Rule 19 governs instead (covered in Section 1.11). Confusing these two regimes is a classic exam trap.

Rule 12 — Sailing Vessels

When two sailing vessels approach so as to involve risk of collision, Rule 12 assigns the give-way duty by the wind:

• Different tacks: the vessel with the wind on her port side keeps out of the way of the other.
• Same tack: the vessel that is to windward (upwind) keeps out of the way of the vessel to leeward (downwind).
• Doubt: if a vessel with the wind on her port side sees a vessel to windward and cannot tell whether that vessel has the wind on port or starboard, she keeps out of the way.

The windward side is the side opposite to that on which the mainsail is carried. Remember: this rule applies only when both vessels are sailing. If either is under engine power, it is a power-driven vessel and Rules 13-15 apply instead.

Rule 13 — Overtaking (overrides everything)

Rule 13 is the single most important priority rule in this section because it overrides every other steering rule:

"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."

The overtaking vessel is always the give-way vessel, no matter what type each vessel is. A sailing vessel overtaking a power-driven vessel must keep clear — the normal sail-over-power priority is switched off during an overtake. This is a favorite trap: the exam describes a sailboat coming up from astern of a motorboat and asks who gives way; the answer is the sailboat, because it is overtaking.

The 22.5-degrees-abaft-the-beam definition

How do you know you are overtaking rather than crossing? Rule 13 gives a precise geometric test:

"A vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22.5 degrees 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 sternlight of that vessel but neither of her sidelights."

Unpack this:

• A vessel's beam is the line straight out to her side (90 degrees from the bow).
• 22.5 degrees abaft the beam is 22.5 degrees behind that beam line — i.e., 112.5 degrees from dead ahead on each side.
• The two 22.5-degrees-abaft-the-beam points define the 135-degree arc of the sternlight. If you are anywhere within that stern arc, you would see only the white sternlight — not the red or green sidelight — and you are overtaking.
• If you can see one of her sidelights, you are forward of the 22.5-degrees-abaft-the-beam line, and the situation is a crossing (Rule 15), not an overtaking.

The night-time sidelight/sternlight test is the practical way to apply this at sea and a frequent exam question.

Doubt resolves toward overtaking

"When a vessel is in any doubt as to whether she is overtaking another, she shall assume that this is the case and act accordingly."

Because the overtaking duty (keep clear) is more demanding, doubt defaults to the more cautious status.

Once overtaking, always overtaking

"Any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel... or relieve her of the duty of keeping clear of the overtaken vessel until she is finally past and clear."

You cannot escape the give-way duty by edging forward until you would technically see a sidelight. Once you began the pass as an overtaking vessel, you remain the give-way vessel until you are finally past and clear.

Worked Example: Sailboat Astern

A sailing vessel approaches a 32-foot power cruiser from a position 40 degrees abaft the cruiser's beam and begins to pass. Is the sailboat privileged? No. At 40 degrees abaft the beam the sailboat is well inside the cruiser's sternlight arc — she would see only the cruiser's white sternlight — so she is overtaking and must keep out of the way, even though sail normally has priority over power. And under "once overtaking, always overtaking," she keeps that duty until she is fully past and clear, even if she later draws up abeam.

Exam Framing

Memorize three numbers/phrases cold: more than 22.5 degrees abaft the beam; only the sternlight, neither sidelight; and overtaking vessel keeps out of the way regardless of type. Add "when in doubt, assume you are overtaking" and "once overtaking, always overtaking." Those five facts answer the overwhelming majority of Rule 13 questions.