Observe and identify
Developing level, about 2 min. International COLREGs / IRPCS.
The situation
A vessel ahead is showing a daytime shape. Inspect the shape and its vertical arrangement with the binoculars. The vessel’s name and status are withheld until your answer.
Which operation or status does this daytime signal indicate?
- Aground
- Restricted ability to manoeuvre
- Not under command
Answers and explanations
Lookout: Three black balls in a vertical line identify a vessel aground. This is a fixed authored state; neither zero speed nor proximity to land establishes it.
The sound answer
Aground
Three black balls in a vertical line identify a vessel aground. This is a fixed authored state; neither zero speed nor proximity to land establishes it.
Why the other options fall short
Restricted ability to manoeuvre
Restricted ability to manoeuvre uses ball, diamond, ball. The displayed signal here indicates aground. Three black balls in a vertical line identify a vessel aground. This is a fixed authored state; neither zero speed nor proximity to land establishes it.
Not under command
Not under command uses ball, ball. The displayed signal here indicates aground. Three black balls in a vertical line identify a vessel aground. This is a fixed authored state; neither zero speed nor proximity to land establishes it.
Rule 30(d) · Day shapes
Three black balls in a vertical line identify a vessel aground. This is a fixed authored state; neither zero speed nor proximity to land establishes it.