COLREG / ARPA / AIS Bridge Rule 23(b) Rule 23(c) 🔒 Course / Premium

Rule 23(c) — WIG Craft (Wing-in-Ground)

NIGHT. A sleek low-flying craft with stubby wings skims just above the surface.

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Scenario briefing

NIGHT. A sleek low-flying craft with stubby wings skims just above the surface. She shows normal PDV lights (masthead + sidelights + sternlight) AND an additional all-round high-intensity FLASHING RED light. Which vessel type is this?

Applicable COLREG rule(s)

Rule 23(b) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

Rule 23(c) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

📸 Night recognition — 8 aspects

The same vessel rendered every 45° of aspect — bow, starboard bow, beam, quarter, stern, port quarter, beam, bow. Use this strip to learn how the lights present from each approach angle. Click any image to view full size.

WIG (Wing-In-Ground) craft on the water viewed head-on (bow aspect) — COLREG Rule 23(c) night-recognition diagram — Bow

WIG (Wing-In-Ground) craft on the water viewed from her starboard bow — COLREG Rule 23(c) night-recognition diagram — STBD bow

WIG (Wing-In-Ground) craft on the water viewed from her starboard beam — COLREG Rule 23(c) night-recognition diagram — STBD beam

WIG (Wing-In-Ground) craft on the water viewed from her starboard quarter — COLREG Rule 23(c) night-recognition diagram — STBD qtr

WIG (Wing-In-Ground) craft on the water viewed dead astern (stern aspect) — COLREG Rule 23(c) night-recognition diagram — Stern

WIG (Wing-In-Ground) craft on the water viewed from her port quarter — COLREG Rule 23(c) night-recognition diagram — Port qtr

WIG (Wing-In-Ground) craft on the water viewed from her port beam — COLREG Rule 23(c) night-recognition diagram — Port beam

WIG (Wing-In-Ground) craft on the water viewed from her port bow — COLREG Rule 23(c) night-recognition diagram — Port bow

Key teaching points

Rule 23(c): a WIG craft only, when taking off, landing and in flight near the surface, shall in addition to the lights for PDV exhibit a HIGH-INTENSITY all-round FLASHING RED light.
Otherwise (afloat, conventional displacement), she shows normal PDV lights (Rule 23(a)/(b)).
WIGs travel at 60–150 kt — far faster than displacement vessels — and need wide berth.

Common mistakes to avoid

Treating the flashing red as a distress signal or as a navigational warning — Rule 23(c) makes it a WIG-only identifier.
Misjudging the WIG's closing speed because the visual size doesn't reconcile with the radar TCPA — she really is doing 100+ kt.

Why it matters

Wing-in-ground (WIG) craft are rare commercial traffic — but when they fly above the surface, they appear visually as power-driven vessels with an additional flashing red light. The pattern was added to COLREG in 2003 specifically because WIGs were colliding with conventional vessels.

Exam relevance

Rule 23(c) WIG lights are a niche topic but appear in STCW OOW orals; rare in yachting exams.

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