The International Regulations for Preventing Collisions at Sea — universally called COLREGs — are international maritime law. The current version (consolidated 1972, amended through 2024) is binding on every commercial and recreational vessel on the open ocean and in coastal waters of every signatory nation. The US adopted COLREGs as the operative collision rules in 1980; they apply to your boat the moment it leaves a slip in Shilshole.
For a recreational PNW cruiser, the working version of COLREGs is short. About a dozen rules cover almost every situation a 35-foot cruising sailboat will see. This article walks through them, in the order they actually come up on a passage.
The rule that overrides all the others
Rule 2 of COLREGs — the Responsibility rule — is the one that survives every other rule. It says, in working translation:
Nothing in these rules shall exonerate any vessel, or its owner, master, or crew, from the consequences of any neglect to comply with these rules or of the neglect of any precaution which may be required by the ordinary practice of seamen, or by the special circumstances of the case.
In other words: avoiding the collision is more important than enforcing your right-of-way. A sailboat with right-of-way that holds course into a converging powerboat and gets hit is not blameless under COLREGs. The sailor who saw the collision developing and did not act has neglected the precaution required by ordinary seamanship.
Every other rule on this page is subject to Rule 2. The right-of-way frameworks below tell you who should give way. Rule 2 tells you that, if the other vessel does not give way, you give way. Avoid the collision. Sort out the legal blame in port.
Sailboat against sailboat
Three rules govern two sailing vessels meeting under sail.
Same tack — windward gives way. When both boats are sailing with the wind on the same side (both on starboard tack, or both on port), the boat that is closer to the wind direction (the windward boat) gives way to the boat further from the wind (the leeward boat). The leeward boat holds course; the windward boat alters.
Different tacks — port gives way. When the boats are on opposite tacks (one with wind from port, one with wind from starboard), the port-tack boat gives way to the starboard-tack boat. Tack is determined by which side the wind is on, which is the same as which side the boom is opposite to: boom on the right (starboard) means wind on the left (port), so port tack.
Overtaking — overtaker gives way. When one sailboat is overtaking another from astern (more than 22.5° abaft the beam), the overtaking vessel gives way regardless of tack or sail trim. This is a rare situation under sail; common under power.
A working summary: starboard tack beats port tack; on the same tack, leeward beats windward; in any overtaking situation, the overtaker gives way.
Sailboat against power vessel
A sailing vessel under sail has right-of-way over a power vessel.
But there are exceptions, and they matter:
- A sailboat with its engine running is, under COLREGs, a power vessel. Even if the sails are up. The masthead light at night and the cone-shaped day shape forward are how you signal I am under power despite the rig.
- A sailboat overtaking a power vessel (rare, but possible downwind) gives way.
- A sailboat in a narrow channel does not impede the safe passage of a vessel that can navigate only within the channel — usually a commercial ship.
- A sailboat anywhere near a vessel constrained by draft, restricted in ability to manoeuvre, engaged in fishing with gear deployed, or with traffic-priority status (see vessel hierarchy below) gives way to it.
The headline — sail beats power — is true on a small recreational scale. Against a 250-metre bulk carrier in the Strait of Juan de Fuca, the headline is reversed by the vessel hierarchy rule. See below.
Power vessel against power vessel
Three situations.
Head-on. Two power vessels approaching head-on or nearly head-on each alter course to starboard. Both boats turn right; both pass port-to-port. This is the rule that applies in approach situations where you can see both sidelights of the other vessel.
Crossing. Two power vessels converging at an angle. The vessel that has the other on its starboard (right) side gives way; the other holds course. The boat on your right has right-of-way. Memorise this. It is the most-used rule in any congested marina or cruising area.
Overtaking. The overtaking vessel gives way regardless of which side. Defined as approaching from more than 22.5° abaft the other’s beam.
In any of these situations, Rule 2 trumps. If the other vessel has not seen you and is not giving way, you give way. Sound five short blasts (the danger signal) on your horn if you have one; alter course early; do not stand on a converging course while the other vessel proceeds toward you.
The vessel hierarchy
Not every vessel is equal under COLREGs. The order of priority, top to bottom (the higher gives way to nothing below it):
- Vessels not under command (NUC) — disabled, drifting
- Vessels restricted in ability to manoeuvre — dredges, cable layers, divers down
- Vessels constrained by draft — large commercial ships in narrow channels
- Fishing vessels with nets, lines, or trawls deployed
- Sailing vessels under sail
- Power-driven vessels
- Seaplanes on the water
Each level on the list gives way to anything above it. This is why a 35-foot sailboat under sail — which has right-of-way over a 50-foot recreational powerboat — gives way to a 90-foot fishing vessel hauling a longline, or to a 200-metre bulk carrier in the Vancouver-bound shipping lane in the Strait of Juan de Fuca.
In practice, the relevant levels for a PNW recreational cruiser are: anything commercial or constrained gives way to nothing. Stay clear of dredges in Elliott Bay, of fish boats with gear in the water near Friday Harbor, of bulk carriers in the Strait. Right-of-way is academic when the other vessel’s stopping distance is one nautical mile.
Traffic Separation Schemes
The Strait of Juan de Fuca, the approaches to Seattle and Vancouver, and the Strait of Georgia all have IMO-designated Traffic Separation Schemes (TSS) — paired one-way lanes for inbound and outbound commercial traffic with a separation zone between them.
Recreational vessels may transit but with strict procedure:
- Cross at a right angle to the lanes — never travel along them
- Do not impede vessels using the lanes
- Stay clear of the separation zone where possible
- Monitor Channel 13 when crossing or operating near the lanes; commercial traffic uses 13 for bridge-to-bridge
The TSS in the Strait of Juan de Fuca runs from the Pacific entrance east to Port Angeles and on to the Vancouver and Seattle approaches. It is heavily trafficked: bulk carriers, container ships, tankers, large fishing vessels, ferries. A recreational cruiser crossing this water on a foggy summer morning is invisible without AIS. Cross at a right angle; cross fast; clear the lane.
Lights, briefly
This article does not cover navigation light configuration in detail — see Night Sailing for that. The COLREGs lights summary every cruiser must know:
Underway power vessels show: a white masthead light forward, red sidelight on the port (left) side, green sidelight on the starboard (right) side, white stern light.
Underway sailing vessels show the same except the white masthead light, unless the engine is running — then the masthead is on too.
Anchored vessels show a single all-around white light visible 360°.
Vessels at anchor over 50 metres show two all-around white lights, one near the bow and one near the stern.
Special-status vessels — fishing, towing, restricted manoeuvre, NUC — show distinctive light combinations defined in COLREGs Rules 26–30. They are the visual equivalent of do not cross my bow.
Reading another vessel’s lights
The principle: red and green tell you which way they’re pointed; white tells you they’re either coming at you (masthead) or moving away (stern).
| You see | They are |
|---|---|
| Both red and green plus white above | Power vessel coming at you, head-on or near head-on |
| Green only | Vessel is angling to your left; you are on its port side |
| Red only | Vessel is angling to your right; you are on its starboard side |
| White only (stern light) | Vessel moving away from you |
| Red over white | Fishing vessel with gear deployed |
| Three vertical reds | Vessel not under command |
A vessel showing only its green sidelight is presenting its right side to you. Apply the crossing rule: if it is on your starboard side, you give way; if on your port side, it gives way (in theory). In either case, watch for relative motion. If the bearing to the vessel is not changing as it approaches, you are on a collision course — bearing constant, range decreasing equals collision.
Sound signals
In good visibility, sound signals are how power-driven vessels communicate intent in close-quarters situations:
- One short blast (1 second): I am altering course to starboard
- Two short blasts: I am altering course to port
- Three short blasts: I am operating astern propulsion (reverse)
- Five or more short blasts: Danger — I do not understand your intentions or I doubt you are taking sufficient action to avoid collision
In restricted visibility (fog, heavy rain, sometimes night), the sound-signal rules change:
- Power vessel underway: one prolonged blast (4–6 seconds) every 2 minutes
- Sailing vessel underway: one prolonged followed by two short, every 2 minutes
- Vessel at anchor: rapid bell ringing for 5 seconds every minute (or air horn substitute)
If you are in fog, your horn is mandatory. Most cruising boats carry a hand-pumped or compressed-air horn that meets the audibility requirement. Test it before the season starts.
Narrow channels
Two rules for narrow channels (Rosario Strait at the south end, the Hiram M. Chittenden Locks approach, the Lake Washington Ship Canal):
Stay to starboard. Vessels in a narrow channel keep to the starboard (right) side of the fairway. This is the maritime equivalent of right-hand traffic.
Do not impede. Smaller vessels (under 20 metres) and sailing vessels do not impede the passage of vessels that can navigate only within the channel — typically large commercial vessels constrained by draft.
The combination means that a sailboat tacking against the wind in a narrow channel, in the path of an inbound tanker, is doing something COLREGs explicitly forbids. Find another route or wait.
After a collision
If a collision occurs:
- Render assistance to the other vessel and persons aboard, if it can be done safely. This is required by both COLREGs Rule 2(b) and US federal law.
- Exchange identification — vessel name, registration, owner contact, insurance.
- Report to the USCG — required for any collision causing injury, death, or property damage exceeding $2,000. Form CG-2692 within 5 days.
- Document everything — photographs, GPS track, witness contact information, the time, weather, and visibility.
- Contact your insurer.
- If significant damage or injury, consult a maritime attorney before signing or saying anything.
Standing by the other vessel and rendering assistance is non-negotiable. Failure to do so is a federal offence.
The summary, in working order
The cruiser who has internalised COLREGs operates by the following hierarchy:
- Avoid the collision. Always. (Rule 2.)
- Identify the other vessel’s status — pleasure, sail, power, commercial, constrained.
- Determine right-of-way using the crossing / overtaking / head-on framework.
- If you have right-of-way, hold course at constant speed. If you must give way, alter early and decisively.
- Use sound signals and lights as required.
- Watch for relative bearing change. If the bearing is constant, the vessels will collide.
Ten rules cover most situations. One rule — Rule 2 — overrides all of them.
The boat that obeys every rule and still collides is the boat that did not obey Rule 2.
Related: Marine VHF Radio · Night Sailing · Navigation Basics · Marine Safety Equipment