Part CIntermediate
Rule 22: Visibility of lights
Specifies minimum visible range for each light type by vessel length category.
Detailed Explanation
Rule 22 gives mandatory minimum ranges:
(a) Vessels 50 m+ — masthead 6 nm; sidelight 3; stern 3; towing 3; all-round white/red/green/yellow 3.
(b) Vessels 12 to <50 m — masthead 5 nm (or 3 if <20 m); sidelight 2; stern 2; towing 2; all-round 2.
(c) Vessels <12 m — masthead 2; sidelight 1; stern 2; towing 2; all-round 2.
(d) Inconspicuous partly submerged towed vessel/object — all-round white 3 nm.
Key Points
- Masthead: 6 NM (≥50m), 5 NM (12-50m), 3 NM (<12m)
- Sidelights: 3 NM (≥50m), 2 NM (12-50m), 1 NM (<12m)
- Know the range table—wrong range = non-compliance
Examples
- Your vessel is 45 m LOA. The masthead light must be visible at a minimum of 5 nautical miles per Rule 22(b), not the 6-mile requirement that applies to vessels 50 m or over.
- A 10 m motorboat's sidelights are only visible at 1 mile. Rule 22(d) requires a minimum 1 NM range for sidelights on vessels under 12 m, so it complies — but just barely.
Common Mistakes
- Fitting lights with sufficient intensity for the wrong vessel length class, resulting in non-compliant visibility ranges.
- Assuming all navigation lights have the same minimum range regardless of vessel size.
- Not realizing that a vessel between 12 and 50 metres has different range requirements from one over 50 metres.