What is a "heaving line" primarily used for?

A heaving line is primarily used for towing or assisting in mooring due to its lightweight and ease of handling. It typically consists of a long, thin line with a weight attached to one end, making it easier to throw and reach other vessels or objects. The heaving line enables the crew to establish a connection with another vessel or to assist in tying up a vessel at the dock.

In mooring situations, the heaving line can be thrown to a crew member on the dock or another vessel, allowing for a more efficient and safe approach to connecting larger lines that are difficult to manage directly. This functionality is crucial for maintaining safety and efficiency in potentially tight or challenging mooring situations.

While the other options mention important aspects of maritime operations, they do not capture the primary use of a heaving line in assisting with towing or mooring.