Navculus Signals

Vessel type

Tow length > 200 m

For towing vessels: enables third masthead light and diamond shape (Rule 24).

Using auxiliary engine

For sailing vessels: shows cone (apex down) day shape (Rule 25(e)).

Show 2nd Masthead Light

Rule 23(a)(ii): Optional for vessels < 50m; mandatory for ≥ 50m.

Max speed ≤ 7 kts (PDV < 7 m)

For power-driven vessels <7 m: affects all‑round white light and sidelights requirement (Rule 23(d)(ii)).

Length overall (LOA) [meters]

Critical thresholds: L<12m, 12-20m, 20-50m, 50-100m, >100m

At anchor / underway? (affects lights)

Show 3D Markings & Labels

Identify FWD, AFT, and specific light names in 3D.

Select vessel parameters & click generate
to see light, shape & sound signals

Based on COLREG 1972 (rules 20-31, 34-35, annex I & III). For professional use only.