Day Shape

A prescribed geometric shape displayed by day to indicate a vessel’s status, operation or restriction under the collision regulations.

Balls, cones, diamonds and cylinders, normally black, are displayed singly or in specified combinations and orientations. They can indicate circumstances such as anchoring, being aground, not under command, restricted manoeuvrability, fishing, sailing while also under power or being constrained by draught.

The correct display depends on vessel size, operation and applicable rule, including position and separation requirements. Shapes communicate status but do not replace lookout or grant absolute priority, and an observer should identify the full combination rather than infer meaning from one component.