Time for action – using a NURBS surface to make the mainsail

You have used Subdivision Surfaces to model the sloop's hull and Bézier curves to make the rudder and keel. Now, you will use a NURBS (Non Uniform Rational B Spline) surface to make the mainsail:

1. Press Ctrl + NumPad 3 to see the Left view. Zoom out so you can see the whole sloop.
2. Press Shift + S and select Cursor to Center.
3. Put the cursor between the boom and gaff in the middle of where the sail will be.
4. Press Shift + A. Choose Add Surface and then NURBS Surface.
5. In the Tool Shelf's Add Surface Patch subpanel, check the Align to View checkbox.
6. Press the Tab key to get into Edit Mode.
7. In the Properties window, select the Object Data button; it has two dots that hold up a surface at one end.
8. In the Properties window, the Active Spline subpanel appears; check the checkboxes for Endpoint: U and Endpoint: V.
9. In the 3D View, zoom into the area between the boom and the gaff. Press A to deselect all the control points. Press...