The fine-tuning of sails and rig — mast rake, shroud tension, outhaul, cunningham, vang. Consistent trim wins more over a season than any spectacular single manoeuvre.
Two identical boats with the same sailor feel different in the same breeze, and the difference is almost always trim, not talent. The controls: mast rake shifts the sail's centre of effort aft and changes the load you feel on the helm. Shroud tension decides how far the mast may bend — more tension means a stiffer rig in strong wind. The outhaul flattens the lower third of the sail, the cunningham pulls creases out of the leading edge, and the vang controls how far the top of the sail twists open. Two habits get in the way: copying tuning tables blindly, and changing everything at once so you never learn what worked. One variable per run, and write down wind and setting. Also factor in your body: a rig set to depower earlier is slower on paper and faster over the full distance, once hiking fatigue arrives.