What device allows the anchor line to spin freely?

The device that allows the anchor line to spin freely is the swivel. A swivel is designed to permit the anchor chain or line to rotate without twisting, which can be particularly important when an anchor is being deployed or retrieved. This rotation helps to maintain the integrity of the anchor line, prevents tangling or kinking, and ensures that the anchor can respond effectively to changes in water movement and direction.

In contrast, while a windlass is a mechanical device used to raise and lower the anchor, it does not provide the same freedom of movement for the anchor line. Similarly, a cleat is a fastening device used to secure lines on a boat and does not allow for free spinning. The hawse pipe is a tunnel through which the anchor chain passes, guiding it to the anchor locker or storage area, and while it aids in anchor deployment, it does not facilitate the line’s ability to spin freely. The swivel is specifically engineered to accommodate rotational movement, making it the correct answer.