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?
- At anchor
- Constrained by draught
- Sailing vessel using machinery
Answers and explanations
Lookout: One black ball identifies a vessel at anchor. Give room for her hull and swinging area; a zero-speed underway vessel has a different status.
The sound answer
At anchor
One black ball identifies a vessel at anchor. Give room for her hull and swinging area; a zero-speed underway vessel has a different status.
Why the other options fall short
Constrained by draught
Constrained by draught uses cylinder. The displayed signal here indicates at anchor. One black ball identifies a vessel at anchor. Give room for her hull and swinging area; a zero-speed underway vessel has a different status.
Sailing vessel using machinery
Sailing vessel using machinery uses cone-down. The displayed signal here indicates at anchor. One black ball identifies a vessel at anchor. Give room for her hull and swinging area; a zero-speed underway vessel has a different status.
Rule 30(a) · Day shapes
One black ball identifies a vessel at anchor. Give room for her hull and swinging area; a zero-speed underway vessel has a different status.