A vessel is being propelled by both sail and engines. Under the Rules, the vessel is a

Answer: B — A power-driven vessel

In the Rules of the Road, vessels are classified by how they are propelled. A sailing vessel is propelled by sails alone and not by any engine, while a power-driven vessel is propelled by machinery. If a vessel uses both sails and an engine to move, the engine provides propulsion, so it falls into the power-driven category. That classification is important because the applicable rules—such as who must keep clear or how predictable actions are—are written with these categories in mind. A sailing vessel would follow the sailing-specific rules, but once engine propulsion is present, the vessel is governed by the power-driven rules. The other descriptions don’t fit because they describe vessels that are either sailing-only, not propelled at all, or use a term not used for the formal regulatory classification in the Rules.