Stern Light
Definition, Placement, and Compliance for Safe Nighttime Navigation
Plain-English Definition
A stern light is a white navigation light mounted near the rear (stern) of a vessel. It shines in an arc of 135 degrees, visible to other boats approaching from behind or from slightly off to either side.
Together with the masthead light (or all-round light) and sidelights, the stern light helps other mariners determine your vessel’s direction, speed, and movement at night or in low visibility.
What a Stern Light Tells Other Boaters
When another vessel sees your stern light, they can quickly understand:
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They’re approaching you from behind or off your quarter
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You’re moving away or at anchor, depending on other lights shown
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How to safely maintain distance and avoid collision
A correctly installed stern light is essential for situational awareness on the water, especially during nighttime travel.
Required Coverage and Visibility
To comply with U.S. Coast Guard (USCG) and International COLREGs regulations, stern lights must meet the following requirements:
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Color: White
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Arc of visibility: 135 degrees
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Position: Fixed at or near the stern, showing light from directly astern to 67.5 degrees on each side
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Minimum visibility distance:
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2 nautical miles for vessels under 50 meters
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3 nautical miles for vessels over 50 meters
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Operation: Must be displayed whenever underway at night or in restricted visibility
Where to Mount a Stern Light
Proper mounting ensures full visibility and compliance:
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Place the stern light on the vessel’s centerline, facing aft
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Mount it above the deck and clear of obstructions like railings, engines, or towers
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On sailboats, ensure it’s separated vertically from the tri-color or anchor light if both are fitted
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Test from astern and 45 degrees abeam to verify full 135° illumination
Installation Best Practices
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Use tinned marine-grade wire and sealed connectors to prevent corrosion
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Mount on a stable, vibration-free surface
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Apply marine sealant around fasteners to prevent leaks
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Test at night to confirm beam pattern is unobstructed and correctly aimed
Common Stern Light Mistakes
Avoid these frequent errors:
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Mounting too low, causing water, wake, or passengers to block the beam
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Using a non-certified light without USCG or COLREG marking
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Installing at an incorrect angle that narrows visibility
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Allowing deck or underwater lighting to overpower the stern light
Quick Spec Checklist
Before you buy, confirm your stern light includes:
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USCG and COLREG certification
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2 NM or 3 NM visibility rating (depending on vessel size)
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IP67 or IP68 waterproofing
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UV-stable, corrosion-resistant housing
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12V or 24V DC compatibility
DRSA-Recommended Stern Lights
Explore reliable, USCG-compliant options engineered for long service life and harsh marine conditions.
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Perko Horizontal Mount Stern Light – 12V
Compact and durable, this classic stern light meets USCG 2 NM visibility standards with corrosion-resistant housing. -
Lumitec Contour Series Stern Light
Sleek and low-profile, offering precision optics, IP67 sealing, and integration with modern hardtops or arches. -
Lopolight Series 200-012 LED Stern Light – 2 NM
Military-grade construction with 50,000-hour LED lifespan, suitable for both recreational and commercial vessels. -
Aqua Signal Series 34 Stern Light – LED
Compact all-purpose stern light, ideal for small powerboats, tenders, and sailboats.
All DRSA-recommended fixtures feature long-life LEDs, low power draw, and marine-grade waterproofing to withstand saltwater, UV exposure, and vibration.
Example in a Sentence
“The yacht’s stern light glowed bright and steady, marking her position clearly to the fishing boats following in the channel.”
Related Marine Terms
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Masthead Light – Forward-facing white navigation light visible 225°
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Sidelights – Red and green lights visible from the front or sides
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Anchor Light – 360° white light displayed when stationary
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All-Round Light – Full-circle light used at anchor or on small vessels