Power-driven vessel underway
White masthead light(s), green and red sidelights, white sternlight. From the side: a white masthead light above a sidelight. From ahead: two whites (the after one higher) plus green and red.
Drag across the scene to walk around the ship. Tap a light to see its name.
Lights (Rule 23)
| Light | Colour | Sector | Height above water |
|---|---|---|---|
| white forward masthead light | white | masthead, 225° (from right ahead to 22.5° abaft the beam on each side) | 16 m |
| white after masthead light, higher and abaft (50 m and over) | white | masthead, 225° (from right ahead to 22.5° abaft the beam on each side) | 20.5 m |
| green sidelight (starboard) | green | sidelight, starboard, 112.5° | 13 m |
| red sidelight (port) | red | sidelight, port, 112.5° | 13 m |
| white sternlight | white | stern, 135° (around the stern) | 6 m |
Model: a 90 m ship with the superstructure aft. Heights and positions follow COLREG Annex I (positioning of lights).
Fog signal
One prolonged blast at intervals of not more than 2 minutes when making way (Rule 35a); two prolonged when underway but stopped (Rule 35b).
A short blast lasts about 1 second, a prolonged blast 4 to 6 seconds (Rule 32). The play button is in the trainer above.
What to watch for
The second (after) masthead light is compulsory from 50 m of length. Below 50 m it may be shown, but does not have to be.
A vessel under 12 m may instead show one all-round white light and sidelights.
Quick answers
What lights does a power-driven vessel underway show at night?
White masthead light(s), green and red sidelights, white sternlight. In full: white forward masthead light; white after masthead light, higher and abaft (50 m and over); green sidelight (starboard); red sidelight (port); white sternlight.
What is the fog signal of a power-driven vessel underway?
One prolonged blast at intervals of not more than 2 minutes when making way (Rule 35a); two prolonged when underway but stopped (Rule 35b).