What is the primary tool used to measure wind speed at sea?

The primary tool used to measure wind speed at sea is the anemometer. An anemometer works by using rotating blades or cups that catch the wind; the speed at which these rotate correlates directly with the wind speed. This instrument is essential for navigation, weather forecasting, and ensuring safety at sea by providing data on wind conditions that can affect vessel performance and maneuverability.

While a barometer is used to measure air pressure and can provide weather-related information, it does not directly measure wind speed. A gyrocompass is a tool that helps determine the true north direction based on rotational movement, and sonar is primarily used for underwater navigation and detecting objects in water rather than measuring atmospheric conditions. Thus, the anemometer is the specific instrument designed for the task of measuring wind speed at sea.