Sailboat Navigation Lights — Complete Scenario Guide
Navigation lights are the language vessels use to communicate their status, direction, and intentions at night and during restricted visibility. Getting them wrong is not just illegal — it causes collisions. This guide covers every common scenario a sailboat owner will encounter, with light configurations organized by boat size and presented as clear visual charts.
Legal basis: Navigation light rules in the US are governed by COLREGS (International Regulations for Preventing Collisions at Sea) and the US Inland Navigation Rules (33 CFR). Both are enforced by the US Coast Guard. Lights are required from sunset to sunrise and during any period of restricted visibility (fog, rain, mist, snow), regardless of time of day.
Light Types, Colors & Arcs of Visibility
Understanding what each light is and where it shines is the foundation of navigation light rules. Every light has a specific color, arc of visibility, and location on the vessel.
Port Sidelight — Red
112.5° arc — from dead ahead to 22.5° abaft port beam. Left (port) side only. Tells approaching vessels they are looking at your port side.
112.5° arc — from dead ahead to 22.5° abaft port beam. Left (port) side only. Tells approaching vessels they are looking at your port side.
Starboard Sidelight — Green
112.5° arc — from dead ahead to 22.5° abaft starboard beam. Right (starboard) side only. Tells approaching vessels they are looking at your starboard side.
112.5° arc — from dead ahead to 22.5° abaft starboard beam. Right (starboard) side only. Tells approaching vessels they are looking at your starboard side.
Stern Light — White
135° arc centered on dead astern. Visible from behind and both quarters. Tells vessels astern they are overtaking you.
135° arc centered on dead astern. Visible from behind and both quarters. Tells vessels astern they are overtaking you.
Masthead / Steaming Light — White
225° arc forward — from 22.5° abaft port beam, through dead ahead, to 22.5° abaft starboard beam. Shown when engine is running. Signals power-driven vessel.
225° arc forward — from 22.5° abaft port beam, through dead ahead, to 22.5° abaft starboard beam. Shown when engine is running. Signals power-driven vessel.
Tricolor Light — Red/Green/White
Single masthead fitting combining port sidelight (red, 112.5°), starboard sidelight (green, 112.5°), and stern light (white, 135°). Only for sailboats under 20m. Only when sailing with engine OFF.
Single masthead fitting combining port sidelight (red, 112.5°), starboard sidelight (green, 112.5°), and stern light (white, 135°). Only for sailboats under 20m. Only when sailing with engine OFF.
All-Round White — 360°
Visible from all directions (360°). Used as anchor light (masthead) and as the only light on very small vessels. Never used underway in addition to navigation lights.
Visible from all directions (360°). Used as anchor light (masthead) and as the only light on very small vessels. Never used underway in addition to navigation lights.
Red Over Green — Optional
Two all-round lights — red above green — at the masthead. Optional additional signal for a sailing vessel under sail only. NOT a substitute for sidelights/stern light. Rarely seen; not required.
Two all-round lights — red above green — at the masthead. Optional additional signal for a sailing vessel under sail only. NOT a substitute for sidelights/stern light. Rarely seen; not required.
Strobe Light — White or Orange
50–70 flashes per minute. Distress signal only. Never use a strobe as a navigation light — it signals you are in distress and need immediate assistance.
50–70 flashes per minute. Distress signal only. Never use a strobe as a navigation light — it signals you are in distress and need immediate assistance.
Tricolor vs. Steaming light — the most common mistake: The tricolor masthead light can ONLY be used when sailing with the engine completely off. The moment you turn on the engine — even just to charge batteries — you must switch to the steaming (masthead) light + separate sidelights + stern light configuration. You cannot run both at the same time. Most electrical panels have a switch labeled "SAIL" and "MOTOR" — use it correctly.
Light Requirements by Boat Size
Under 7 Meters (~23 ft) — COLREGS Rule 25(d)
Rule 25(d)| Light | Under Sail | Under Power | Anchored |
|---|---|---|---|
| Port sidelight (red) | ▲ if practical | ▲ if practical | — |
| Starboard sidelight (green) | ▲ if practical | ▲ if practical | — |
| Stern light (white) | ▲ if practical | ▲ if practical | — |
| Masthead / steaming light | — | ▲ if practical | — |
| Tricolor (masthead) | ▲ if practical | — | — |
| All-round white (anchor) | — | — | ▲ if practical |
| Minimum required | White flashlight or lantern — ready to show to prevent collision | ||
Key rule: Boats under 7m are not required to carry or show navigation lights. However, you MUST have a white flashlight ready at hand at all times and use it immediately to prevent collision. In practice, always install proper lights — the flashlight rule is a minimum, not a recommendation.
7–20 Meters (~23–65.6 ft) — Most Recreational Sailboats
Rule 25(a)(b)(c)| Light | Sail Only | Motor-Sailing | Anchored |
|---|---|---|---|
| Port sidelight (red) | ● | ● | — |
| Starboard sidelight (green) | ● | ● | — |
| Stern light (white) | ● | ● | — |
| Masthead / steaming (white) | — | ● REQUIRED | — |
| Tricolor (masthead) | ● OR above 3 | — ILLEGAL | — |
| Red over green (optional) | ▲ optional add-on | — | — |
| All-round white (anchor) | — | — | ● REQUIRED |
Under sail: You have two legal options — Option A: Separate port sidelight + starboard sidelight + stern light. Option B: Tricolor at masthead (replaces all three). Option B uses less battery and is easier for other vessels to see from distance. Option A is required if you're also using the steaming light position for another purpose.
Over 20 Meters (~65.6 ft)
Rule 25(a)| Light | Sail Only | Motor-Sailing | Anchored |
|---|---|---|---|
| Port sidelight (red) — separate unit | ● | ● | — |
| Starboard sidelight (green) — separate unit | ● | ● | — |
| Stern light (white) — separate unit | ● | ● | — |
| Masthead / steaming (white) | — | ● REQUIRED | — |
| Tricolor (masthead) | — NOT ALLOWED | — NOT ALLOWED | — |
| Red over green (optional) | ▲ optional | — | — |
| All-round white (anchor) | — | — | ● Forward required |
| Second all-round white (anchor — 50m+) | — | — | 50m+ only |
Key difference over 20m: Sidelights and stern light MUST be separate units — no combined bi-color lights allowed. Tricolor is prohibited at any length over 20m. All three lights must shine with the specified arc from their own independent fittings.
Light visibility range requirements:
Masthead/steaming light: 2 miles (vessels under 12m) / 3 miles (vessels 12–50m)
Sidelights: 1 mile (under 12m) / 2 miles (12–50m)
Stern light: 2 miles (under 12m) / 2 miles (12–50m)
Anchor light: 2 miles (under 50m) / 3 miles (50m+)
Tricolor: 2 miles minimum (under 20m only)
Masthead/steaming light: 2 miles (vessels under 12m) / 3 miles (vessels 12–50m)
Sidelights: 1 mile (under 12m) / 2 miles (12–50m)
Stern light: 2 miles (under 12m) / 2 miles (12–50m)
Anchor light: 2 miles (under 50m) / 3 miles (50m+)
Tricolor: 2 miles minimum (under 20m only)
All Navigation Light Scenarios
Scenario 1 — Daytime, Fair Visibility, Underway
Rule 20(b)| Light / Signal | Under 7m | 7–20m Sail | 7–20m Motor | Over 20m |
|---|---|---|---|---|
| All navigation lights | OFF | OFF | OFF | OFF |
| Black ball shape (at anchor) | ▲ if anchored | ▲ if anchored | ▲ if anchored | ● REQUIRED if anchored |
| Black cone shape (motor-sailing) | n/a | ▲ if motoring too | n/a (motor vessel) | ▲ if sails up + motoring |
No lights are required during the day in good visibility. A black ball (sphere) shape must be displayed if at anchor. If a sailboat is motor-sailing (engine on, sails up) during the day, she must display a black cone point-down to signal she is acting as a power-driven vessel.
Scenario 2 — Sailing at Night, Engine Off
COLREGS Rule 25(a)(b)(c)| Light | Under 7m | 7–20m Option A | 7–20m Option B | Over 20m |
|---|---|---|---|---|
| Port sidelight (red, 112.5°) | ▲ if practical | ● | — (tricolor) | ● |
| Starboard sidelight (green, 112.5°) | ▲ if practical | ● | — (tricolor) | ● |
| Stern light (white, 135°) | ▲ if practical | ● | — (tricolor) | ● |
| Tricolor (masthead — R/G/W) | ▲ if practical | — (using A) | ● | — PROHIBITED |
| Masthead / steaming light | — | — | — | — |
| Red over green (optional) | — | ▲ add-on optional | ▲ add-on optional | ▲ add-on optional |
Battery tip: The tricolor masthead light is the most efficient option for sailing at night. It uses a single bulb (or LED), gives better visibility from distance than deck-level sidelights, and significantly reduces battery draw. Most cruising sailors use the tricolor when sailing under sail only.
Scenario 3 — Motor-Sailing (Engine On, Sails Up or Down)
COLREGS Rule 23 + Rule 25| Light | Under 7m | 7–20m | Over 20m |
|---|---|---|---|
| Masthead / steaming light (white, 225°) | ▲ if practical | ● REQUIRED | ● REQUIRED |
| Port sidelight (red, 112.5°) | ▲ if practical | ● | ● |
| Starboard sidelight (green, 112.5°) | ▲ if practical | ● | ● |
| Stern light (white, 135°) | ▲ if practical | ● | ● |
| Tricolor (masthead) | — | — ILLEGAL when motoring | — PROHIBITED |
Critical: When the engine is running, you are legally a power-driven vessel regardless of whether sails are up. Turn OFF the tricolor and turn ON the steaming (masthead) light plus deck-level sidelights and stern light. This is the single most commonly violated navigation light rule among sailors.
Scenario 4 — At Anchor at Night
COLREGS Rule 30| Light | Under 7m | 7–50m | Over 50m |
|---|---|---|---|
| All navigation lights (underway) | OFF | OFF | OFF |
| All-round white light (forward/masthead, 360°) | ▲ if practical | ● REQUIRED | ● |
| Second all-round white (aft, lower) | — | — | ● REQUIRED |
| Black ball shape (daytime) | ▲ if practical | ● REQUIRED | ● REQUIRED |
Placement: The anchor light should be at or near the masthead for maximum visibility. Modern LED anchor lights draw very little power and should be left on all night. Many sailors use the same all-round white fitting for both anchor light and the optional "sailing at night" purposes — verify your wiring and switch labels are correct before anchoring.
Exception: Vessels under 7m are not required to show an anchor light if not in or near a narrow channel, fairway, or anchorage, or where other vessels normally navigate. In practice, always show a light — the exception is not an excuse to be invisible.
Scenario 5 — Working on Deck at Night
Rule 20 + seamanshipNo change to navigation lights — continue to display the correct lights for your current status (anchored or underway). Additional practices:
| Light / Practice | Anchored | Underway |
|---|---|---|
| Navigation lights | ● Anchor light | ● Normal nav lights |
| Spreader lights / deck lights | ▲ use as needed for work | ▲ use cautiously |
| Red-light cockpit lighting | ● Recommended | ● Preserves night vision |
| White spreader/deck lights | ▲ fine at anchor | Caution underway — can impair other vessels' ability to see your nav lights |
Night vision warning: White deck lights destroy your own night vision for 20–30 minutes. Use red cockpit lighting (red LED strips, red headlamp) to preserve night vision while on watch. If you must use white spreader lights for deck work underway, post an additional lookout with unaided night vision on the bow.
Scenario 6 — Restricted Visibility (Fog, Rain, Snow, Mist)
COLREGS Rules 19, 35| Action | Required? | Details |
|---|---|---|
| Navigation lights | ● YES — even during daylight | All lights for your vessel status must be on any time visibility is restricted, regardless of time of day |
| Sound signal — under sail | ● REQUIRED every 2 min | One long + two short blasts every 2 minutes |
| Sound signal — under power | ● REQUIRED every 2 min | One long blast every 2 minutes |
| Sound signal — at anchor | ● REQUIRED | Ring bell rapidly for 5 seconds every minute |
| Radar reflector | ● Highly recommended | Hoist radar reflector to maximum height; carbon fiber hulls have extremely low radar signature |
| Speed | ● Reduce to safe speed | COLREGS Rule 19: proceed at a "safe speed" — be able to stop within half your visibility distance |
| Lookout | ● Post dedicated lookout | Both visual AND aural — listen for fog signals from other vessels; bow lookout separate from helm |
| AIS / Radar | ● Monitor continuously | AIS shows vessels with transponders; radar shows all vessels including those without AIS |
Fog is extremely dangerous. Commercial vessels may be doing 20+ knots and cannot stop quickly. In fog, reduce speed, start your engine, post a bow lookout, and make sound signals. Do not trust AIS alone — not all vessels have AIS. If possible, navigate to shallow water away from shipping channels and anchor.
Scenario 7 — Emergency / Not Under Command
COLREGS Rule 27A vessel "not under command" is one that through exceptional circumstances is unable to maneuver — engine failure, rudder failure, steering failure, medical emergency, etc. This status gives you right of way over all other vessels except those constrained by draft.
| Signal | Day | Night |
|---|---|---|
| Two all-round red lights (vertical) | — | ● REQUIRED |
| Two black balls (vertical, shapes) | ● | — |
| Sidelights and stern light | — | ● If making way |
| VHF Channel 16 announcement | ● Strongly recommended | ● Strongly recommended |
Two red all-round lights in a vertical arrangement signal "not under command." Few recreational sailors carry these lights; in practice, use VHF Ch. 16, flares, and any other available signals to communicate your status to approaching vessels.
Scenario 8 — Man Overboard (MOB)
Annex IV + seamanship| Action | Priority | Details |
|---|---|---|
| Shout "Man Overboard" | ● IMMEDIATE | Alert all crew; assign one person to keep eyes on the MOB — never look away |
| Throw horseshoe buoy / life ring | ● IMMEDIATE | Throw toward the MOB; it provides flotation AND marks position with dye marker and light |
| Press MOB button on GPS/chartplotter | ● Within seconds | Marks GPS position of MOB immediately — do not delay |
| MOB light (horseshoe buoy) | ● Auto-activates in water | Water-activated white strobe on horseshoe buoy; 8+ hour battery; auto-activates on contact with water |
| Searchlight on MOB (night) | ● Illuminate immediately | Keep searchlight or powerful flashlight on the person in the water; do not let them disappear from visual |
| VHF Pan-Pan call (Ch. 16) | ● Urgency call | "Pan-Pan, Pan-Pan, Pan-Pan — man overboard, position [lat/lon], vessel [name]" |
| Navigation lights — vessel | ● Normal lights | Maintain normal navigation lights for your vessel status; add spreader lights to illuminate recovery area |
Night MOB is extremely serious. A person in dark water at night is nearly invisible. The horseshoe buoy strobe light and a dedicated crewmember with eyes on the MOB are the only ways to maintain contact. Practice MOB drills in daylight before sailing at night.
Scenario 9 — Distress (Life in Danger)
COLREGS Annex IV, Rule 37| Signal | Visibility | Day | Night |
|---|---|---|---|
| EPIRB activated | Global (satellite) | ● | ● |
| VHF "MAYDAY" — Ch. 16 | 20–50 nm VHF range | ● | ● |
| Orange smoke (day only) | 10+ nm | ● | — |
| Red parachute flare | 25–40 nm | ● | ● |
| Red handheld flare | 3–5 nm | ● | ● |
| White strobe light (50–70 flashes/min) | 5+ nm | — | ● |
| SOS by any light or sound | Varies | ● | ● |
| Slowly raise/lower outstretched arms | Visual range | ● | — |
| Orange distress flag | Visual range | ● | — |
| PLB (Personal Locator Beacon) | Global (satellite) | ● | ● |
Use distress signals only when life is in danger. Misuse of distress signals (including accidental EPIRB activation) is a federal offense. Register your EPIRB with NOAA — an unregistered beacon will trigger a full Coast Guard response that cannot be cancelled without a search. EPIRB registration: beaconregistration.noaa.gov
Master Quick-Reference Chart
● = ON — = OFF ▲ = Optional ✕ = ILLEGAL to use in this scenario (S) = Sound signal required
| Scenario | Port Sidelight (Red) | Starboard Sidelight (Green) | Stern Light (White) | Tricolor Masthead (under 20m) | Steaming / Masthead Light (White) | All-Round White (360°) | Red Over Green (Optional) | White Strobe (Distress) | Sound Signal |
|---|---|---|---|---|---|---|---|---|---|
| ☀️ Daytime, Underway | — | — | — | — | — | — | — | — | — |
| 🌙 Sailing at Night (engine off) <20m | ● | ● | ● | ▲ OR above 3 | — | — | ▲ | — | — |
| 🌙 Sailing at Night (engine off) >20m | ● | ● | ● | ✕ | — | — | ▲ | — | — |
| ⚙️ Motor-Sailing at Night | ● | ● | ● | ✕ ILLEGAL | ● | — | — | — | — |
| ⚓ At Anchor at Night | — | — | — | — | — | ● | — | — | — |
| 🌫️ Restricted Visibility (Fog) — Under Sail | ● | ● | ● | ▲ or above 3 | — | — | ▲ | — | ● (S) |
| 🌫️ Restricted Visibility — Motoring | ● | ● | ● | ✕ | ● | — | — | — | ● (S) |
| 🌫️ Restricted Visibility — Anchored | — | — | — | — | — | ● | — | — | ● Bell (S) |
| 🆘 Man Overboard (Night) | ● | ● | ● | — | ● if motoring | — | — | — | ● Pan-Pan |
| 🔴 Distress | ● | ● | ● | ▲ | ▲ | — | — | ● + Flares + EPIRB | ● MAYDAY |
Sound Signals Quick Reference
Maneuver Signals (Inland Rules — US Waters)
- 1 short blast — I am altering course to starboard
- 2 short blasts — I am altering course to port
- 3 short blasts — I am operating astern propulsion
- 5+ short blasts — Danger signal; I don't understand your intentions
Fog Signals
- 1 long blast every 2 min — Power-driven vessel underway making way
- 2 long blasts every 2 min — Power-driven vessel underway, stopped
- 1 long + 2 short every 2 min — Sailing vessel underway; vessel not under command; vessel restricted in ability to maneuver; vessel constrained by draft; vessel engaged in fishing; vessel towing/pushing
- Bell 5 sec every 1 min — Vessel at anchor
- Gong after bell — Vessel at anchor over 100m
- 3 strokes + bell 5 sec + 3 strokes every 1 min — Vessel aground
Signal Definitions
- Short blast — approximately 1 second
- Long blast — 4–6 seconds
- Whistle / horn — required on all vessels; carry a handheld air horn as backup
Equipment Required
- Under 12m: Any sound-producing device capable of making the required signals
- 12–20m: A whistle
- Over 20m: A whistle AND a bell
- Over 100m: Whistle + bell + gong
A handheld compressed air horn is the most common and practical solution for boats under 20m. Carry spare canisters — they deplete quickly in cold weather and tend to fail at the worst moment. A battery-powered or mouth-blown horn is a good backup.
Distress Signals — Full Reference
COLREGS Annex IV lists all recognized distress signals. Use any or all of the following when life is in danger and immediate assistance is required.
Electronic / Radio
- EPIRB — 406 MHz satellite beacon; activates a Coast Guard response anywhere in the world; register at beaconregistration.noaa.gov
- PLB (Personal Locator Beacon) — individual crew member device; same satellite system as EPIRB; worn on PFD
- VHF "MAYDAY" on Channel 16 — "MAYDAY MAYDAY MAYDAY, this is [vessel name], position [lat/lon], nature of distress, number of persons on board, any other relevant information"
- DSC Distress button on VHF — red button under cover; sends digital distress with GPS position to all DSC-equipped vessels and Coast Guard
- SOS on any transmitter — · · · — — — · · ·
Pyrotechnic
- SOLAS red parachute flare — rises to 1,000 ft; burns 40 seconds; visible 25–40 nm; most effective signal after EPIRB
- Red handheld flare — burns 60 seconds; 3–5 nm range; signal when rescuer is close
- Orange smoke (daytime) — 3–10 minute duration; highly visible to aircraft and vessels; day use only
Visual (Non-Pyrotechnic)
- White strobe light — 50–70 flashes per minute; night use; visible 5+ nm
- Orange distress flag — black square and circle on orange background; daytime only
- Slowly and repeatedly raise and lower outstretched arms — recognized distress signal when visible to another vessel
- Flames on vessel — burning rags, flares; last resort; fire is a distress signal
Resources
- USCG Navigation Center — official navigation rules, light lists, NOTAMs
- USCG Navigation Rules (PDF) — free official download
- NOAA EPIRB Registration — register your EPIRB; it's free and required
- BoatUS Foundation — Navigation Lights Study Guide
- Boater Education Resources — courses that cover navigation lights in depth