What defines a "vessel not under command" under the Rules?

A "vessel not under command" is specifically defined as a vessel that is unable to maneuver as a result of exceptional circumstances. This may include situations where the vessel is experiencing mechanical failure, such as engine trouble, or situations where the crew is incapacitated or unable to operate the vessel due to circumstances beyond their control.

This definition is crucial because vessels not under command have specific rights and responsibilities under maritime law, particularly in situations involving navigation and right of way. Other vessels must give way to a vessel not under command, as it cannot safely navigate or respond to other vessels in the vicinity.

The other choices do not accurately represent the definition of a vessel not under command. A vessel that is anchored cannot be classified as not under command simply based on its anchoring status, as it may still be able to maneuver if necessary. A vessel engaged in fishing activities is subject to other regulations and could have the ability to maneuver. Similarly, a vessel operating in reduced visibility, such as during fog, is not automatically considered to be not under command if it still retains the ability to navigate safely.