During the day, what does a vessel constrained by draft display?

A vessel constrained by draft displays one black cylinder. This signal is used to signify that the vessel's draft is such that it cannot safely navigate in shallow waters. The black cylinder is part of the day shapes used internationally to communicate a vessel's operating condition to other mariners.

When a vessel is constrained by draft, its ability to navigate is limited by the depth of the water, meaning it may not be able to safely maneuver into a harbor or away from obstructions. The display of the black cylinder is essential for informing other vessels that they should take caution while navigating near the constrained vessel to avoid potential collisions or grounding.

This signal forms part of the maritime regulations outlined in the Colreg (International Regulations for Preventing Collisions at Sea), aimed at enhancing safety and navigation awareness on the water. Understanding these visual signals is crucial for all mariners in ensuring safe passage and avoidance of accidents at sea.