Moving this forward moves the center of effort forward. The line of maximum camber. Twist refers to the curved line made by the leech of the sail. This is shown in figure 4. More twist reduces the force on the upper part of the sail.
Twist is the curvature of the leech.
To locate the following, refer to figures 5 and 6. 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.