Observe and identify
Developing level, about 2 min. IALA worldwide marks.
The situation
A navigation light lies ahead. Start playback and watch at least one complete cycle. Its period is an illustrative charted example; identify the combination of colour and rhythm.
Which mark matches the light you observe?
- South cardinal
- North cardinal
- East cardinal
Answers and explanations
Lookout: Both cones point down; black is below yellow. Six quick flashes are followed by a long flash.
The sound answer
South cardinal
Yellow above black, with both cones pointing down. Six quick or very quick white flashes followed by a long flash. The long flash distinguishes six from nine. Pass south.
Why the other options fall short
North cardinal
Black above yellow, with two cones pointing up. White continuous quick or very quick flashes. The named northern side is the indicated side for passage; check the chart for the danger and clearance. Here the observed cue identifies south cardinal. Yellow above black, with both cones pointing down. Six quick or very quick white flashes followed by a long flash. The long flash distinguishes six from nine. Pass south.
East cardinal
Black–yellow–black, with two cones pointing apart. White light in groups of three quick or very quick flashes. Pass on the eastern side and establish clearance from the chart. Here the observed cue identifies south cardinal. Yellow above black, with both cones pointing down. Six quick or very quick white flashes followed by a long flash. The long flash distinguishes six from nine. Pass south.
Cardinal marks
Yellow above black, with both cones pointing down. Six quick or very quick white flashes followed by a long flash. The long flash distinguishes six from nine. Pass south.