What is the purpose of a fin stabilizer on a ship?

A fin stabilizer on a ship serves to counteract the ship's roll, which is the side-to-side movement caused by waves or other environmental factors. By reducing the amplitude of rolling motions, fin stabilizers help to improve onboard comfort for passengers and crew and maintain operational efficiency. As the fins are deployed in the water, they generate lift, which counteracts the forces causing the roll, allowing the ship to remain more upright.

While other options might seem plausible, they do not accurately reflect the primary purpose of a fin stabilizer. Improving fuel efficiency or enhancing propulsion are more closely related to the ship's hull design and propeller efficiency rather than stabilizers. Stabilizing navigation equipment also does not pertain directly to the primary function of fin stabilizers, as navigation equipment is typically stabilized through different means. Thus, the primary role of a fin stabilizer is clearly to mitigate the ship's roll, enhancing stability and safety during voyages.