If your yacht falls in the 12 to 20 metre range, there are specific international regulations under the COLREGs (International Regulations for Preventing Collisions at Sea) that apply to your navigation lights for boat safety — and they’re not the same as those for smaller vessels under 12 m.
This article breaks down exactly what’s required for navigation lights for 12–20 m sailboats, where the key cut-offs are, and how to avoid common compliance issues — all in straightforward, sailor-friendly language.
Where’s the cut-off?
The rules apply to your boat’s length overall (LOA), not waterline length or hull length.
- Under 12.00 m: categorised as a “<12 m” vessel.
- 12.00–19.99 m: grouped with vessels up to 50 m, but still under a special “<20 m” bracket that grants some helpful options.
- 20 m and above: into a different compliance tier, with more demanding specs.
If your yacht is 12.00 m or longer, the guidance here is tailored to you.
Navigation lights for boat use under sail (engine off)
When sailing under wind power alone, the regulations require:
- Sidelights – red (port) and green (starboard), each covering 112.5°.
- Sternlight – white, covering 135°.
Schematic of navigation light arc coverage (sidelights, masthead, stern)
Optional setups (for yachts under 20 m):
- Masthead tricolour lantern, combining red, green, and white into one fitting at or near the masthead.
- Bi-colour lantern at the bow (red/green) combined with a sternlight.
⚠️ Only one system can be active at a time — either deck-level lights or masthead tricolour.
Visibility range (how far the navigation lights must be seen)::
- Sidelights: 2 nautical miles (nm)
- Sternlight: 2 nm
- Tricolour navigation lights: each sector must meet 2 nm minimum
Navigation lights for boat operation under engine
The moment the engine is on (even if the sails are up), your boat becomes a power-driven vessel. The sailing light setup must be switched off, and you must show a different configuration.
Required navigation lights for 12–20 m sailboats under power:
- Masthead (steaming) navigation light – white, 225°, visible from 3 nm
- Sidelights – red/green, each visible from 2 nm
- Sternlight – white, visible from 2 nm
Mounting height requirements (this trips many people up):
- The masthead light must be installed at least 2.5 m above the gunwale.
- It must also be higher than the sidelights and clear of obstructions.
- Sidelights should be no more than ¾ the height of the masthead light.
⚠️ A common mistake is fitting a steaming light too low on a coachroof or radar arch — non-compliant for yachts 12–20 m.
Key difference vs. <12 m boats:
Smaller boats can use an all-round white light + sidelights as a shortcut, but this is not allowed once over 12 m LOA.
Motor-sailing during the day
When sailing with the engine running, you must also display:
- Black cone, point down in the foretriangle or another visible location.
This day shape is mandatory for boats 12 m and up, though exemptions exist in some inland waters.
At anchor
At night, a yacht at anchor must show:
- One all-round white light — usually at the masthead.
By day:
- Black ball displayed in a visible position.
Minimum light visibility: 2 nm.
Lopolight Navigation Lights
Common mistakes to avoid
Even experienced owners and boatyards occasionally miss the mark on light compliance. Some things to watch out for:
❌ Using a 2 nm steaming light on a 12–20 m boat — it must be 3 nm.
❌ Leaving the masthead tricolour on while motoring. Only one set of lights should be active at a time.
❌ Mounting your masthead light too low — below the required 2.5 m.
❌ Obstructed light arcs — from davits, radar domes or sails. Make sure your lights are clearly visible in all directions.
Pre-sail checklist for 12–20 m yachts
Here’s a simple checklist before heading out:
✔ Under sail: Use deck-level sidelights + sternlight or masthead tricolour (not both).
✔ Under power: Masthead light (3 nm), sidelights (2 nm), sternlight (2 nm). Masthead must be ≥ 2.5 m above the gunwale.
✔ Motor-sailing by day: Black cone displayed.
✔ At anchor: One all-round white (2 nm) visible; black ball by day.
What changes at 12 metres?
As soon as your boat hits 12.00 m LOA, the key upgrades include:
- Longer visibility range for the masthead light (3 nm vs. 2 nm)
- Stricter mounting heights
- Loss of the small-boat shortcut (no more all-round white + sidelights under power)
But you do keep the option for a masthead tricolour when sailing — as long as you use it correctly and switch to the proper set when motoring.
Final thoughts about navigation lights
Understanding the correct navigation lights for boat compliance between 12–20 m is essential for safety and predictability on the water. Always confirm the NM rating stamped on your fittings, check mounting heights, and ensure no obstructions block the light arcs.
At Upffront, we supply a wide range of navigation lights for boats in this size category, engineered for full COLREG compliance and reliable offshore performance.
👉 Explore our navigation lights range byb clicking below or contact us if you have any questions:
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Navigation Lights for Boat Owners: Rules for 12–20 m Sailboats