The naval architect must have a basic knowledge of everything that relates to her construction. He must consider the choice of materials (steel, aluminium, wood, plastics) and relate his assessments to the individual vessel's displacement, tonnage, and measurement, trim, stability, freeboard, seaworthiness, steering, speed, and propulsion. He must also be competent to advise on the choice of engine and boiler design which will provide the power required, and to-day the nuclear powered ship foreshadows immense new design possibilities. Nor is this all; the naval architect must possess practical knowledge of a ship's auxiliary machinery, electrical, refrigerating and air-conditioning, ventilation, life-saving equipment, winches and lifting tackle. He must also be conversant with docking requirements, ship repairing, shipyard practice generally, and be experienced in the several main factory processes, welding etc. Of considerable design importance today is a full appreciation and knowledge of hydrodynamics and the value of ship model experiment work carried out in the several testing tanks, e.g. at UTM Johor.