When instructed to "Slack (line #)", what should be done?

When instructed to "Slack (line #)", it means that you should release tension on the line. This command is commonly used in nautical operations where lines, also referred to as ropes, are under tension. Releasing tension allows for more flexibility in the line, which is necessary for various tasks, such as adjusting the position of a vessel or facilitating maneuvers without putting excessive strain on equipment or personnel.

This action is crucial for maintaining safety and efficiency on board, as having too much tension can lead to injuries or equipment damage. In scenarios like docking, anchoring, or adjusting sails, knowing when to slack a line is an essential skill for ensuring proper handling and maneuverability of the vessel.