Sailing Right-of-Way Rules: COLREGs Made Simple

Most “sailing right of way rules” arguments start with Rule 12 or “sail over power.” That’s usually the wrong starting point. COLREGs is a collision-avoidance system first, and a priority system only when everything else is working.

When I’m on watch, I stack the rules in this order: lookout (Rule 5), safe speed (Rule 6), risk (Rule 7), action (Rule 8)—then I worry about who is stand-on or give-way. It keeps you out of the courtroom and, more importantly, out of the water.

Photo by Markus Spiske on Unsplash

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COLREGs First Principles: “Right of Way” Isn’t a License (Rules 5–8)

Rule 5 Lookout: Seeing Early Beats Arguing Later

Rule 5 is blunt: maintain a “proper lookout” by sight and hearing and all available means. “Available means” includes radar, AIS, your ears, and that gut feeling that the ferry looks a bit too interested in you. ABYC H-1 (Field of Vision) matters here because dodgers, biminis, and a 135% genoa can hide an entire fishing boat in your blind arc.

In practice, many training syllabi teach a scan rhythm of about every 2–5 minutes in open water, and more often in traffic. That’s guidance, not a COLREG number, but it’s a useful discipline when you’re tired at 0200. If you’re in a busy approach channel, your scan interval might be 30–60 seconds, because targets are changing faster than your coffee cools.

Rules 6–7: Safe Speed and Risk of Collision (Constant Bearing)

Rule 6 never gives you a “safe speed” in knots, because safe speed depends on visibility, traffic density, maneuverability, background lights, wind/sea/current, and draft constraints. If you can’t stop or maneuver within an appropriate distance, you’re going too fast—especially in rain squalls where visibility collapses from 2 NM to 0.5 NM in a minute. The best sailors I know reduce speed early, not after the AIS alarm screams.

Rule 7 is where most close calls become obvious: constant bearing + decreasing range = risk of collision. Use a hand-bearing compass (or even a fixed reference on your dodger frame) and take two bearings 2 minutes apart. If the bearing is steady and the range is shrinking, you’ve got a problem regardless of who “has rights.” AIS CPA/TCPA is excellent corroboration, but Rule 7 warns against over-reliance on any single method, especially when targets have no AIS or bad data.

Rule 8: Early, Substantial, and Unambiguous Maneuvers

Rule 8 rewards decisiveness. “Nibbling” 5° at a time is how skippers create interpretive dance routines instead of collision avoidance. Many instructors teach that a course change of ≥20–30° is usually large enough to be readily apparent, and that guidance matches what I see work in real traffic. If you need to slow down, slow down—don’t pretend you’re still making way while your wake says otherwise.

Here’s the decision clock I use: range, closing speed, and minutes to CPA. If you’re 1.0 NM apart and closing at 10 knots, that’s roughly 6 minutes to impact (60/10 = 6). Six minutes disappears fast when you’re reefing, calling the crew, and trying to figure out if that “sailing vessel” is motor-sailing with a tricolor.

Practical tip (Rule 5–8 habit): If you can’t describe the situation in one sentence—“constant bearing, range decreasing, CPA under 0.5 NM in 8 minutes”—you’re not assessing risk clearly enough to act early.

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Sailboat vs Sailboat: Port/Starboard Tack and Windward/Leeward (Rule 12)

Different Tacks: Port Tack Keeps Clear of Starboard

Rule 12 is the classic sail-vs-sail framework: port tack keeps clear of starboard tack. In the cockpit, your fastest tack cue is the boom and headsail telltales, not philosophical debates about “true wind.” If the other boat’s boom is out to starboard, they’re on port tack; if it’s out to port, they’re on starboard tack.

Put numbers on it so you feel the urgency. Two 35 ft (10.7 m) cruisers close-hauled at 6 knots each can have a closing speed around 10–12 knots depending on angle. At 1.5 NM, you may only have 8–9 minutes before it’s uncomfortably close, and that’s before anyone tacks to “prove a point.”

Same Tack: Windward Keeps Clear of Leeward

Same tack is windward/leeward: the windward (upwind) boat keeps clear of the leeward (downwind) boat. The reason is practical, not moral—leeward often has less room to bear away without losing sails or getting rolled. In chop, the leeward boat may also be slower to maneuver because it’s already pressed and tracking hard.

“Keeping clear” doesn’t mean the leeward boat gets to swing up at the last second. If you’re stand-on, you’re still bound by Rule 17 to monitor, and by Rule 8 to take action when it’s apparent the give-way boat isn’t handling it. I’ve watched plenty of “leeward rights” turn into ugly near-misses because the stand-on skipper decided stubbornness was a virtue.

If You Can’t Tell the Other Boat’s Wind Side, Assume You’re Windward

Rule 12 gives you an escape hatch: if you can’t tell the other vessel’s tack/windward side, assume you’re the windward boat and keep clear. That’s not surrender; it’s seamanship. Glare, swell masking, and a boat sailing “by the lee” can confuse even sharp eyes at 0.7 NM.

A simple sail-vs-sail decision tree helps when your brain is busy trimming and avoiding lobster pots:

Bring it back to Rule 7–8: don’t wait until you’re close-hauled, pinching, and out of options. Make your action early and obvious—a clean tack, a 30° bear-away, or a slowdown if that’s what opens CPA the most.

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Overtaking, Crossing, Head-On: Angles That Decide (Rules 13–15)

Rule 13 Overtaking: The 22.5° Abaft-the-Beam Test

Rule 13 is the one sailors mess up because they think it’s about speed alone. It’s about relative bearing: if you’re coming from more than 22.5° abaft the beam, you are overtaking, and you are the give-way vessel. That obligation “sticks” until you’re finally past and clear, even if the other boat changes course a bit.

From the cockpit, the quick check is: can you see their sternlight sector at night, or are you clearly in their aft quarter by day? If you’re uncertain because the other vessel is yawing, assume you are overtaking and act like it. The sea doesn’t award points for being technically correct while still colliding.

Rules 14–15 for Power-Driven Vessels: Head-On vs Crossing

Rules 14 and 15 apply to power-driven vessels, which matters because many “sailing” situations are actually motor-sailing or involve powerboats. Rule 14 head-on is simple: if you’re meeting on nearly reciprocal courses, both alter to starboard for a port-to-port pass. Don’t get clever and go left unless you enjoy explaining yourself later.

Rule 15 crossing: if you have the other vessel on your starboard side, you’re the give-way vessel and should avoid crossing ahead when possible. That’s not just etiquette; it’s about removing ambiguity. A small 5–10° alteration can look like nothing on the other boat’s compass, while a proper 20–30° turn is legible.

Making Your Action ‘Readily Apparent’ in Mixed Traffic

Here’s a real-world overtaking timeline that wakes people up. You’re doing 6 knots under sail. A planing powerboat is doing 18 knots and approaches from your aft quarter. Your closing speed is about 12 knots, so 1.0 NM closes in 5 minutes—and that assumes they keep course.

My helm flow is consistent: confirm situation (bearing + AIS if available), choose the safest maneuver that opens CPA, execute clearly, then re-check CPA/TCPA. If I’m the give-way vessel, I avoid sliding across their bow by “just a little,” because that’s how you end up in the worst possible place: directly in front of someone who thinks you’re predictable.

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When the Sailboat Does NOT Have Priority (Rules 9, 10, 18 + Motor-Sailing)

Rule 18 Priority Hierarchy: Where Sailing Actually Sits

Rule 18 is where the “sail always has right of way” myth goes to die. In broad strokes, the hierarchy puts Not Under Command (NUC) and Restricted in Ability to Maneuver (RAM) above everyone, and often Constrained by Draft (CBD) matters in practice around deep-water routes. Sailing vessels generally sit above power-driven vessels, but not above vessels that simply can’t maneuver like you can.

If you’re near tugs, dredges, ferries, or ships in pilotage waters, assume somebody has less freedom than you do. A tug with a tow isn’t going to “just turn,” and a ship at 12–18 knots in a channel can’t step aside because your genoa is full and your pride is fuller.

Rule 9 Narrow Channels: ‘Do Not Impede’ and the 20 m Threshold

Rule 9 says vessels under 20 m (65.6 ft) and sailing vessels shall not impede a vessel that can safely navigate only within a narrow channel or fairway. That’s most cruising yachts, including your 40 ft (12.2 m) sloop, no matter how salty your logbook looks.

Scenario: you’re sailing along the edge of a dredged channel, and a deep-draft ship is coming up the pipe. Your correct move is to act early outside the channel, not to drift into the channel and then demand “rights.” “Do not impede” means you avoid creating a situation where the ship must take avoiding action; if they must maneuver, you already failed the test.

Rule 10 TSS: Crossing at Right Angles and Planning the Transit

Traffic Separation Schemes punish sloppy planning. Rule 10 says avoid crossing traffic lanes if practicable; if crossing, do so on a heading as nearly as practicable at right angles (~90°) to the traffic flow. The point is to minimize time in the lane and make your intentions obvious.

Mini example: a traffic lane is 2 NM wide. Your yacht makes 6 knots through the water, so a straight perpendicular crossing takes about 20 minutes (2 NM / 6 kn = 0.333 hr). Add set and drift—say 1 knot of cross-current—and your course over ground can skew enough to turn your “90° crossing” into a lazy diagonal that keeps you exposed for 30+ minutes.

This is where planning tools pay off. Use a sea-distance tool to map your route between waypoints to sanity-check the lane width, your planned crossing distance, and time in the scheme at your realistic speed, not your brochure speed. Then add a buffer so you’re not arriving at the separation zone boundary right when the watch changes on the nearest container ship.

Motor-Sailing Gotcha: Your Status Changes

The moment your engine is providing propulsion, you are a power-driven vessel for COLREGs purposes. That changes your responsibilities and usually your lights too, and it definitely changes how commercial traffic interprets you at night. If you’re motor-sailing to hold 6 knots in a chop, don’t assume you still have sailboat privilege; the rules don’t care that the sails are up for comfort.

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Night and Restricted Visibility: Lights, Sound, and Rule 19 Behavior

Seeing and Being Seen: Common Sailboat Light Configurations

At night, most right-of-way mistakes start with misidentifying lights. Typical sailboat setups are either sidelights + sternlight (deck level) or a masthead tri-color offshore. At anchor, it’s an all-round white anchor light, and yes, it needs to work every time, not just on calm weekends.

COLREGs Annex I gives minimum visibility ranges that matter for small craft. For vessels <12 m, sidelights must be visible 1 NM and the sternlight 2 NM; for 12 m to <20 m, sidelights are 2 NM and sternlight 2 NM. Those numbers assume proper installation and clean lenses, which is why ABYC A-16 (Electrical Navigation Lights) and corrosion control matter more than people admit.

Restricted Visibility (Rule 19): Why the Playbook Changes

Rule 19 applies when vessels are not in sight of one another—fog, heavy rain, or that nasty sea smoke that turns the horizon into a blank sheet. There’s no “visibility less than X miles” trigger written into the rule. If you can’t see the other vessel, you stop pretending stand-on and give-way will save you.

In restricted visibility, I slow early, put someone on dedicated lookout, and treat AIS/radar as assistants, not referees. For power-driven vessels, Rule 19 cautions against altering to port for a vessel forward of the beam when feasible, because it can increase confusion and converge tracks. The goal is simple: reduce speed, increase time, and make any maneuver large enough to be unmistakable.

Sound Signals and Practical Readiness on Small Craft

Sound signals matter most when visibility is poor and distances collapse fast. COLREGs prescribes patterns (short and prolonged blasts), not consumer loudness specs, but it’s worth knowing that portable air horns are often around 110–120 dB at 1 m. That can be adequate close-in, but it’s not the same as a proper fixed horn on a larger vessel.

USCG carriage requirements for a sound-producing device are not optional paperwork—they’re part of your collision-avoidance toolkit. I also keep the horn where it can be reached in 5 seconds, not buried under a cockpit locker full of “important” fenders. If you need it, you need it now.

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Tools That Make COLREGs Easier: AIS, VHF, Bearings, and Power Integrity

AIS CPA/TCPA: Useful, Not Sufficient

AIS is one of the best upgrades a cruising sailor can buy, but it’s not magic. Targets can be missing (no AIS), misconfigured (wrong ship type), or delayed. Rule 7 still expects “all available means,” which includes your eyes and a bearing check, not just a glowing triangle on a screen.

I typically set CPA alarms around 0.5–1.0 NM offshore, and tighter—maybe 0.1–0.3 NM—in confined harbors, depending on speed and room. Those are operator choices, not regulations, and they should match your stopping distance, your crew readiness, and sea state. A 0.2 NM alarm is worthless if you need 3 minutes to get the autopilot off and sails under control.

Hand-Bearing Compass + ‘Bearing Drift’ Workflow

A hand-bearing compass is still the fastest collision detector I know. Take a bearing, wait 2 minutes, take it again, and compare. If the bearing is steady and range is shrinking, you don’t need a committee meeting.

ISO 19009 covers compass and azimuth reading device performance for small craft, and it’s a reminder that compass placement matters. A cheap compass near a speaker magnet is a comedy routine until you try to hold a steady bearing at night. If you want the “constant bearing” test to mean anything, your compass has to be trustworthy.

VHF/DSC: Clarifying Without Negotiating Away COLREGs

VHF is best used to identify and clarify, not to invent new rules on the fly. If I’m calling a ship, I want its name from AIS, and I keep it short: position, intention, and confirmation. DSC is valuable when configured correctly, but it’s not a substitute for maneuvering early and obviously.

Power integrity matters more than people admit. AIS, VHF, and nav lights all depend on clean DC power and wiring, which is where ISO 10133/13297 and ABYC A-16 show up in real life. A corroded negative bus can turn your “seen” plan into darkness, and darkness is a lousy way to assert right of way.

If you’re planning a night crossing of a busy lane, run the timing with a quick nautical-mile check for your crossing leg using your conservative speed, not your best-day speed. It’s also handy for fuel planning when you know you’ll be motor-sailing and therefore operating as power-driven in traffic.

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Common Gotchas + Cockpit Cheat Sheet (What Skilled Skippers Do)

Stand-On Stubbornness and the Rule 17 ‘Last Responsible Moment’

Rule 17 is where stand-on vessels get into trouble. Yes, the stand-on vessel should generally maintain course and speed, but must act when it becomes apparent the give-way vessel isn’t taking appropriate action. There’s no numeric trigger like “at 0.3 NM you may panic,” which is why good skippers build their own thresholds based on closing speed and sea room.

My personal rule: if CPA is trending under 0.5 NM and TCPA is under 10 minutes, I’m already preparing to maneuver, even if I’m stand-on. When it’s time to act, I act decisively—usually a 20–30° alteration or a clear slowdown—so the other vessel can read it immediately.

Autopilot, Fatigue, and the Lookout Failure Pattern

Autopilot is great at holding a compass course and terrible at keeping you alive. The common failure pattern is: autopilot on, heads down on a plotter, scan interval stretches from 2–5 minutes to “whenever,” and suddenly a ship is much closer than it should be. ABYC H-1 exists because real boats have real blind spots, and autopilot doesn’t lean around the dodger to check them.

If you’re short-handed at night, reduce workload early: reef sooner, tidy lines, set alarms, and keep a strict scan cycle. It’s also smart to estimate your fuel needs based on the voyage distance so you’re not scrambling if you end up motor-sailing longer than planned in traffic.

Glare, Background Lights, and Misreading Motor-Sailing

Shore lights can hide sidelights, and tri-colors can confuse tired eyes into thinking a vessel is farther away than it is. The motor-sailing trap is worse: a yacht under power may still look like “a sailboat” until you notice the power-driven light pattern. The rules don’t care how romantic the sails look; if machinery is propelling the boat, it’s treated as power-driven.

Here’s the cockpit cheat sheet I keep in my head:

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Frequently Asked Questions

In a sail-vs-sail meeting, how do you determine windward/leeward when apparent wind is shifted by current or a strong gust line, and what does Rule 12 require if you’re unsure?

Use what the boats are actually doing: boom position, telltales, and who is physically upwind at that moment, rather than arguing about theoretical true wind. Rule 12 is categorical: different tacks means port keeps clear of starboard; same tack means windward keeps clear of leeward. If you can’t determine the other boat’s wind side, Rule 12 requires you to assume you are windward and keep clear, then make an early, obvious maneuver per Rule 8.

Using Rule 13, how can you confirm an overtaking situation from the cockpit with relative bearings (including the >22.5° abaft-the-beam criterion) when the other vessel is yawing?

Treat it as overtaking if you are generally in the stern sector—more than 22.5° abaft the beam—even if the target yaws a few degrees. Check where the vessel sits relative to your beam over 2–3 minutes; if it stays aft of your beam and you’re closing, you’re the overtaker and therefore the give-way vessel. When in doubt, assume overtaking and keep clear until you’re clearly past and the other vessel is opening behind you.

When motor-sailing, which navigation lights must a sailing yacht show to be treated as power-driven, and what are the common misidentification risks at night?

If the engine is providing propulsion, you are treated as a power-driven vessel, and you should display the power-driven light configuration applicable to your vessel (not just sail-only lights). The common risk is showing a sailboat tri-color or sail-only pattern while actually under power, causing others to assume you have sailing-vessel privileges or different maneuver expectations. The second risk is partial lighting from wiring faults—why ABYC A-16 style installation and corrosion control matter—creating an unidentifiable “mystery craft” that nobody can interpret confidently.

For Rule 10 TSS crossings, how do you plan a perpendicular (~90°) transit on a chartplotter while accounting for set and drift so your course over ground stays near right angles?

First, determine the lane’s general traffic direction, then plan a heading that makes your course over ground as close to 90° as practicable, not merely your heading through the water. Use current vectors (or observed set/drift) to aim slightly up-current so the resulting COG is near perpendicular, reducing time in the lane. Run the timing—e.g., 2 NM at 6 knots ≈ 20 minutes—and add buffer for steering error and sea state, so you aren’t tempted into last-second zig-zags.

How should you combine a hand-bearing compass ‘constant bearing’ check with AIS CPA/TCPA to comply with Rule 7 without over-relying on AIS targets or CPA alarms?

Use the bearing check as the primary “physics test”: take a bearing now and again in about 2 minutes; constant bearing with decreasing range indicates risk under Rule 7. Then use AIS CPA/TCPA as confirmation and to prioritize which contact needs attention first, remembering some vessels have no AIS and some AIS data is wrong. Set CPA alarms conservatively (often 0.5–1.0 NM offshore, tighter in confined waters) and treat alarms as prompts to look outside, not permission to stay heads-down.

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