What is a "sea anchor" primarily used for?

A sea anchor is primarily designed to stabilize a vessel in rough waters. It functions by creating drag in the water, which helps to keep the bow of the vessel facing into the waves, reducing the risk of capsizing and increasing overall safety during storms or rough conditions. This stabilization is crucial for maintaining control of the vessel when maneuvering through turbulent seas, providing a means to ride out unfavorable weather.

The other options pertain to different functions and equipment. For instance, helping a vessel move faster is generally associated with sails or propulsion systems rather than a sea anchor. Entering a harbor safely and assisting with berthing procedures involve navigation techniques and equipment specific to those tasks, rather than utilizing a sea anchor. Thus, the primary role of a sea anchor is distinctly aligned with enhancing stability in adverse maritime conditions.