What is the day signal for a vessel towing astern?

The day signal for a vessel towing astern is represented by one black diamond. This signal helps to clearly communicate the operational status of the towing vessel to other mariners. It indicates to nearby vessels that the depicted vessel is engaged in towing activities, which is essential for ensuring safe navigation and avoiding collisions. The black diamond shape is a standardized visual signal recognized in maritime navigation and is part of the International Regulations for Preventing Collisions at Sea (COLREGs).

The other options represent different signals for other situations at sea, which may not relate specifically to the act of towing a vessel. Understanding the proper day signals is crucial for maintaining safety and effective communication on the water.