Vessels must be _____ of each other to give any maneuvering or warning signals.

For vessels to effectively communicate maneuvering or warning signals, they must be in sight of each other. This requirement is grounded in the need for visual acknowledgment of the signals being exchanged, ensuring that both vessels understand the intentions conveyed. The International Regulations for Preventing Collisions at Sea (COLREGs) highlight that visual signals are essential for maintaining safety and preventing misunderstandings between nearby vessels.

When vessels are out of sight, alongside, or at a distance without being able to see one another, the likelihood of misinterpretation increases. In situations where vessels are far apart or not visible, other methods of communication such as radio might be more appropriate. Therefore, being in sight is crucial for clarity and effective navigation between vessels, allowing crews to respond appropriately to the signals given.