What dayshape must be shown on a partly submerged vessel that is being towed?

When a partly submerged vessel is being towed, it is required to display a diamond dayshape. This shape is used to signal to other vessels that the towed vessel is not navigating under its own power and indicates its unique status. The diamond dayshape is specifically designated for vessels engaged in towing operations and is recognized in the International Regulations for Preventing Collisions at Sea (COLREGs).

The use of the diamond shape effectively communicates to nearby vessels the situation of the towed vessel, which is crucial for maintaining safe navigation and preventing collisions. While the other shapes listed are associated with different types of vessels or operations, the diamond is specifically mandated for a vessel being towed that is partially submerged, emphasizing its importance in maritime safety protocols.