While sailing, the painter is led into the cockpit and stowed in one of the compartments along the side of the boat. Easing the forestay depowers the sail by allowing the mast to tilt away from the wind. This should only be used upwind in heavy air. They should be tighter in light air and looser in heavy air. The Cunningham controls the luff tension.
More tension moves the line of maximum camber forward and slightly reduces the camber.
Off the wind, the vang prevents the boom from rising. The C Scow halyard is half rope and half wire. It should only be used on very low reaches. Thus, the main sheet, rather than the boom vang, is used to adjust the leech tension and maintain sail shape when going upwind. Running backstays relieve some of the tension on the sidestays.