What are sheets used for on a sailing vessel?

Sheets are essential lines on a sailing vessel that are used to control the angle and trim of the sails relative to the wind. By adjusting the sheets, sailors can effectively change how much sail is exposed to the wind, which directly influences the boat's speed and direction. Properly trimmed sails ensure that the vessel sails efficiently, which is key to maximizing performance and maneuverability on the water.

The other options do not accurately describe the function of sheets. For instance, sheets are not used for anchoring the boat or tying sails together; those tasks require different types of lines or equipment. Furthermore, sheets do not influence the speed of the engine, as sailing vessels rely on wind power rather than engine propulsion for their primary movement. Understanding the role of sheets is fundamental for effective sailing practices and overall vessel handling.