ABSTRACT
The approach to design and construction of scaled free-running models is very different. First of all the hull of any such model must be geometrically and dynamically similar to the hull of some real vessel, already existing or under design. The scale is chosen as a compromise between the necessity to reduce as much as possible scale effects (Sutulo and Guedes Soares, 2011) and the desire to make the model as small as possible to facilitate its transportation and handling. From the viewpoint of the scale effect the minimum model length must be not less than 6 meters (8-12 meters are desirable), while models with the length 1-1.5 meters would be the most convenient but considered insufficient for serious studies. The length of 2-3 meters is undesirable but still acceptable. However, the model must accommodate certain amount of nonscalable instruments, sensors and equipment and its ability to carry all necessary payload can be checked with the standard displacement equation used in ship design. If the model is not supposed to be tested in more or less substantial waves it can be executed without sealed upper deck which facilitates access to all elements of the equipment.
