The luff itself is shown as a thick blue line. The horizontal upper and lower seams are shown as a thick green line. Quit Transfer control to the start-up menu. The shape control is provided by the sliders located on the right of the picture frame. They affect the shape of the spinnaker as follow.
Vertical factor Adjust the vertical distribution of depth.
Twist Adjust the twist of the sail by opening the leech and tightening the luff. Very powerful effect on the way the spinnaker will fly. Always use a value of 0 for symmetric spinnaker. Depth Adjust the design depth of the spinnaker in the lower part. Combined with the above twist factor this give you full control of the spinnaker horizontal profile.