Which vessel is required to follow Navigation Rules when operating under power?

A sailboat with its engine engaged is required to follow Navigation Rules when operating under power. This is because once a sailboat's engine is in use for propulsion, it is considered a power-driven vessel. Power-driven vessels must adhere to the same navigation regulations that apply to motorboats, ensuring safe and responsible operation on the water.

In this context, while all vessels must be operated safely and with consideration of rules regarding navigation, a sailboat under power transforms its status and falls under the regulations pertaining to powered vessels. This includes maintaining proper lookout, safe speed, and correct action to avoid collisions, among other rules.

The other vessels listed have different regulatory requirements. A motorboat with sails down is still categorized as a power-driven vessel and must follow the rules applicable to it. A rowboat, being propelled solely by human power, may have different rules, especially regarding right-of-way and navigation. Similarly, while fishing boats operate under specific conditions, they are categorized as powered or unpowered vessels based on their propulsion method and must comply with the appropriate regulations accordingly.