out, are glued together and then cut down to the exact lines of the design, templates being used to test the precision of the curves. In the planked, or built-up model, which is generally chosen by more expert builders, the planks are tacked to the frame, as in the construction of large vessels. Hulls may also be formed from modern plastics, which may be purchased from a manufacturer as thermomoldings or fiberglass layups or fabricated by the modeler, by first making a positive model from clay or plaster (or using an existing model's hull) and then creating a negative mold from fiberglass or plaster. Models may be exaggerated cutters, so far as their underbodies are concerned, or, more often, are fitted with fin-keels weighted, after the manner of full-sized yachts. They may have any rig, but schooner and sloop rigs are most common, the latter being the favorite for racing on account of its simplicity. Mechanical sailing controls For uncontrolled sailing craft some form of steering control is required, since with a fixed rudder position the model will turn into the wind. Three kinds of steering-gear are used, the weighted swinging rudder, the main-sheet balance gear, and the steering vane, the object of each being to keep the model on a true course, either before or against the wind. Models are often sailed without dynamic control of the rudder, but although a perfectly built boat will sail readily against the wind without steering gear, it is almost impossible to keep it on its course before the wind without some contrivance to check for divergence. The setting of the steering gear and sheet positions must be adapted to the wind conditions and this is a subtle art to master. These controls are the traditional methods, for more than 100 years before the advent of radio control and they continue to be used worldwide. Weighted rudder method This is accomplished by the weighted rudder, which falls over when the vessel heels and tends to counteract the force of the breeze. There are two varieties of the weighted rudder, in the first of which the weight, usually lead, is fixed to the edge of the rudder, while in the second the weight, usually a ball of lead, is made to run on the tiller above the deck, so that it can be placed further forward or aft, according to the force needed to