Harden In

To haul in a sheet or other control so that a sail is held closer to the vessel’s centreline.

The instruction is normally used when trimming for a course closer to the wind or reducing excessive sail movement. It describes changing sheet or control tension, not turning the vessel; the helm instruction to turn closer to the wind is harden up.

The correct trim depends on apparent wind, sail type and desired course. Over-sheeting can stall the airflow, increase heel or load the rig unnecessarily, and loaded sheets should be handled through their intended winches, cleats and fairleads.