Sailing at night: a different challenge
Night navigation is a fundamental skill every skipper must master. Whether it is a planned passage, a late arrival at port, or an emergency, sooner or later you will find yourself at the helm in the dark.
At night you lose the visual reference of the horizon, depth perception changes radically, and hazards are harder to detect. However, with proper preparation, sailing at night can be a calm and even magical experience.
Navigation lights: the language of the night
Navigation lights are the only visual means of identifying other vessels and their heading. Knowing them is mandatory and can prevent collisions.
Basic lights on a motorized vessel
- Red to port: visible in an arc of 112.5 degrees from the bow toward port
- Green to starboard: visible in an arc of 112.5 degrees from the bow toward starboard
- White stern light: visible in an arc of 135 degrees from the stern
- White masthead light: visible in an arc of 225 degrees toward the bow, higher than the sidelights
Lights on a sailboat under sail
- Red and green: same as a motorized vessel
- White stern light: same as a motorized vessel
- No masthead light: sailboats under sail do NOT carry a masthead light (this is the key to distinguishing them from a motorboat)
- Optionally: red over green lights at the masthead (sailboats only)
Lights on an anchored vessel
- One white all-round light (360 degrees) visible at 2 miles
- Vessels over 50 meters: two white lights (bow higher than stern)
How to interpret the lights you see
This is the most critical part. When you see lights at sea:
- Red only: the other vessel is showing you her port side, moving right to left in front of you
- Green only: she is showing you her starboard side, moving left to right
- Red and green together: she is heading straight toward you. Head-on situation
- White only: you see her stern, she is moving away from you, or she is anchored
- Masthead + red + green: motorized vessel heading toward you
- Red + green without masthead: sailboat heading toward you (under sail)
COLREG rules for night navigation
The COLREG rules (International Regulations for Preventing Collisions at Sea) always apply, but at night they are especially critical:
Rule 5: Lookout
Maintain permanent visual and auditory lookout. At night this means:
- At least one person on deck watching the horizon at all times
- Scanning the horizon every few minutes through 360 degrees
- Turning off or dimming interior lights to avoid blinding the lookout
- Listening for fog signals from other vessels
Rule 7: Risk of collision
If the bearing of another vessel (the angle relative to your bow) does not change, there is a risk of collision. At night, watch the relative position of the lights:
- If the other vessel's lights remain at the same relative angle, you are on a collision course
- If they move to the right, she will pass behind you
- If they move to the left, she will pass ahead of you
Rule 18: Priorities
At night the right-of-way priorities do not change: 1. Vessel not under command 2. Vessel restricted in ability to maneuver 3. Vessel engaged in fishing 4. Sailing vessel (under sail, no engine) 5. Power-driven vessel
Preparing the boat for night
Before departure
- Check all navigation lights: turn them on and verify they work correctly. Carry spare bulbs
- Charge the batteries: navigation lights must run all night without problems
- Plan the route: mark waypoints on the plotter, identify hazards, and calculate ETA
- Prepare the deck: stow loose lines, close hatches, secure anything that could move
- Prepare food and hot drinks: to keep the crew's energy and morale up
- Assign watches: 2-3 hour shifts so everyone gets rest
Onboard lighting
- Navigation lights: verify visibility and angles
- Instruments: reduce the brightness of plotters and screens to minimum so you do not lose night vision
- Red interior light: use red lights in the cabin to preserve the eyes' adaptation to darkness
- Red headlamp: essential for moving around the deck without blinding anyone
Night vision: how to preserve it
The eyes take between 15 and 30 minutes to fully adapt to darkness. A single exposure to bright white light can destroy that adaptation, and you will need another 15-30 minutes to recover it.
Tips for maintaining night vision
- Use only red light when you need illumination (red light does not affect the eyes' dark adaptation)
- Reduce instrument brightness to minimum
- If you need to consult a chart or document, use a red flashlight
- Avoid looking directly at the lights of other boats or the shore (use peripheral vision)
- Do not use your phone at normal screen brightness (activate night mode or turn it off)
- If someone needs to turn on a white light below deck, warn the lookout first so they can close one eye and preserve vision in that eye
Electronic navigation at night
Plotter and GPS
The plotter is your best ally at night. Configure: - Night mode: black background with dark colors - Brightness to minimum: readable without causing glare - Alarms: set proximity to land alarm, depth alarm, and off-course alarm - AIS active: see nearby vessels with their data on screen
Radar
If you have radar, nighttime is when you appreciate it most: - Detects unlit vessels, floating objects, and the coastline - Use the guard zone function to alert you if anything enters your safety zone - Complements visual lookout but never replaces it
Specific hazards of night navigation
Floating objects
Logs, containers, fishing nets, and other debris are virtually invisible at night. Navigate at moderate speed so you can maneuver if you detect something.
Unlit vessels
Unfortunately, some small craft navigate without lights. Artisanal fishermen, kayaks, and small boats can be invisible. Radar is the only way to detect them.
Coastal light interference
Near the coast, lights from cities, ports, and buildings can make it difficult to identify buoys and navigation lights. Pay special attention to the flashing patterns of buoys and lighthouses.
Fatigue
Fatigue is the greatest real danger of night navigation. A drowsy skipper makes poor decisions and can fall asleep at the helm. Respect the watch schedule and sleep when you are off duty.
Entering port at night
Entering an unfamiliar port at night is a demanding maneuver. Follow these steps:
- Study the chart: identify the entrance alignment, buoys, shallows, and obstacles
- Identify the port lights: look for sector lights and illuminated buoys
- Reduce speed: enter at minimum steerage speed
- Turn on a deck light: to illuminate the berth and make yourself visible in the port
- Have fenders and lines ready before entering
- Contact via VHF if the port has a harbor office or dock attendants on duty at night
Sector lights in ports
Lighthouses and leading lights in ports use color sectors: - Green: safe zone, entrance channel - Red: danger zone, shallows or rocks - White: general sector
The nautical chart shows the exact angles of each sector.
Night navigation checklist
Before sailing at night, verify:
- Navigation lights working correctly
- Batteries charged
- Radar operational (if available)
- Plotter in night mode with alarms configured
- VHF on channel 16
- Red headlamps for all crew
- Life jackets accessible (preferably worn)
- Route planned and waypoints entered
- Watch schedule assigned
- Food and drinks prepared
- Deck clear and secure
Night navigation requires more attention, more preparation, and more experience than daytime sailing. If you are a novice skipper, practice first in familiar waters and good weather before venturing on long nighttime passages.
