Day Skipper theory guide · Lights & shapes
Day Skipper navigation lights: recognise the pattern
At night, one light rarely tells the whole story. Identify the pattern, then ask which lights you can actually see from your angle. These examples concentrate on distinctive all-round lights used in Day Skipper revision.
Practise this topicWhat to look for
Read vertical combinations together
A pilot vessel on pilotage duty shows an all-round white light over an all-round red light. If underway, it also shows sidelights and a sternlight. Two all-round red lights in a vertical line indicate a vessel not under command.
Red, white, red signals restricted manoeuvrability
Three all-round lights in a vertical line, red over white over red, identify a vessel restricted in her ability to manoeuvre. Do not confuse this with two red lights or with a single red sidelight seen from a particular angle.
Aspect matters
Sidelights and a sternlight show different arcs. A missing light in your view may simply be outside its arc or obscured. Keep watching as the bearing and apparent pattern change, rather than deciding from a brief glimpse.
Worked example: white over red
You see two all-round lights in a vertical line: white above red. That is the distinctive pilot-vessel signal while on pilotage duty. If you can also see sidelights and a sternlight, the vessel is underway. Continue to assess the full situation and risk of collision; identifying the vessel is only one part of the decision.
Name the whole pattern before interpreting an individual colour.
A common mistake
Assuming a vessel type from one red light. It could be a sidelight or part of a vertical signal. Check position, number, colour and visibility arc together.
Try three questions
These are independent practice questions. Read the answer and explanation after making your choice.
01At night you see, in line, a white light over a red light. What is the vessel?
Answer: A pilot vessel on duty
A pilot vessel on pilotage duty exhibits an all-round white light over an all-round red light. When underway, she also shows sidelights and a sternlight.
02Two all-round red lights in a vertical line, displayed by a vessel underway, mean…
Answer: Vessel not under command
Two all-round red lights in a vertical line indicate a vessel not under command. The signal identifies her condition; all vessels must still keep a proper lookout and act to avoid collision where possible.
03A vessel restricted in her ability to manoeuvre displays which all-round lights?
Answer: Red-white-red
'Red, white, red' in a vertical line indicates a vessel restricted in her ability to manoeuvre.
Sources and further reading
Examples checked against these primary sources on 27 September 2026. Check the latest editions before using any rule or calculation afloat.
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