You can't control the sail without a line. Made just like the tiller, it shows the flexibility of this technique:
Press A to deselect all objects. In the File menu, select Append.
Find
4909OS_09_sloop_line.blend
.Open the Object folder.
Press A to select the line and the line shape.
In the 3D View, select the line as shown in the following screenshot:
Press the Tab key to get into Edit Mode. You see the control points of the Bezier Curve that creates the line. Press the Tab key to re-enter Object Mode.
In the Properties window header, press the Object Data button. It has two dots connected by a curve. The line is made just the same way as the tiller. In the Geometry subpanel, you will see Line Shape listed as the Bevel Object, as in the following image.
Press Shift + LMB to select Empty. Press Ctrl + P to parent the Empty to the line.
Select Empty and press R, Z, and Z to do a test rotation. Press the RMB when you are done.