What lights must a vessel servicing a pipeline display during the day?

A vessel servicing a pipeline displays three black shapes in a vertical line to indicate its activity, which is a specific signal prescribed for such operations. The configuration, where the highest and lowest shapes are balls and the middle shape is a diamond, is recognized internationally. This visual signal is crucial for other vessels navigating the waters to understand that a pipeline servicing operation is underway, ensuring safety by promoting awareness of potential hazards associated with such operations.

When vessels are engaged in pipeline work, it is important for them to communicate this to others on the water, as the presence of these shapes provides a clear indication of the vessel's role and intention. The use of black shapes, particularly in the specified formation, is a standard adopted in the navigation rules to prevent collisions by providing essential information about the vessel’s purpose and operational status.