NavCAD is a module for rapid performance prediction and analysis of ships, which can be used to select suitable propulsion system units, including the main engine, gearbox, and thrusters. NavCAD is applicable to all kinds of displacement, semi displacement, planing boats, inland river barges and fleets, sailboats and Catamaran. It can also analyze the towing and self propulsion tests of open water propeller, ducted propeller, surface propeller and Pump-jet. NavCAD is different from other similar software in that it is not limited to limited analysis of ship speed in one or two aspects, but provides a complete platform for static balance analysis from the hull to the main engine. It provides strong support for tasks such as minimum hull resistance analysis and multi-objective propeller optimization design. NavCAD believes that the speed of a ship is not the ultimate speed of the ship, nor is it the speed at which the ship chops and chops waves, nor is it the so-called maximum design speed. When each ship navigates in its displacement mode, it generates bow and stern wave systems. As the speed increases, the wavelength also increases, and the phase difference between the two wave systems also alternates. This phase change causes the peak valley of the resistance curve to alternate and become concave convex (which is also the working mechanism of the bulbous bow, where the wave system generated by the bulbous bow compensates and reduces a portion of the bow wave). Designers cannot know the amplitude at the peak and valley of the resistance curve through the calculation of ship speed, but can only know the location where the resistance peak occurs (further analysis shows that many ship parameters affect the size and location of the resistance peak, the most important being the diamond coefficient and the wetting characteristics of the stern seal plate). If there is a peak resistance near the ship's speed, it indicates that the speed here is not economical, but this speed is not an insurmountable physical limit. In short, if possible, ship speed is a speed that should be avoided as much as possible. Adopting the resistance valley value instead of the speed at the peak is the only way to improve the efficiency of the ship. After users input hull performance parameters and select resistance estimation methods, they can apply the minimum hull resistance analysis method to optimize the hull line characteristics. That is, they only need to specify the search range and step size of each parameter change (such as the length, width, longitudinal position of the buoyancy center, etc.), and NavCAD can estimate the resistance of each arrangement combination scheme of the ship and automatically arrange it according to the order of resistance size, The optimal ship type scheme with the lowest resistance is shown at the beginning of the table, and the performance differences between other schemes and the lowest resistance scheme are listed in percentage form. NavCAD can also use the weighted average method to conduct a comprehensive trade-off analysis of the ship's speed at two speeds (usually test speed and service speed for civilian ships, and combat speed and cruise speed for military ships). This feature is unique to NavCAD. NavCAD ensures the accuracy of resistance estimation by taking the following measures: having a method library containing a large number of estimation methods (there are over 30 methods for estimating resistance of bare hulls alone); Using similar compatibility parts between various methods; Perform targeted calculations based on specific technical status; Having a comprehensive analysis environment that ensures that key factors such as shallow water resistance are not overlooked; Able to conduct detailed evaluations and internal inspections. In addition, NavCAD also includes a system for evaluating the applicability of HydroComp's estimation methods. This function can select the most suitable resistance estimation method for a specified ship based on the characteristics of the ship, including the size of the ship's speed, the characteristics of the ship's parameters, and other special parameters (such as the influence of factors such as waterline coefficient and trim introduced in a certain estimation method). When a certain estimation method estimates abnormal results based on the specified ship information, the system will automatically issue a warning message. NavCAD can not only be used as a separate standard tool, but also can be used together with other Naval architecture design software. NavCAD uses parameterized hull data, making it very convenient to input various details of the ship. NavCAD also supports the IMSA Open Ship Data Transfer Standard (IDF), so that ship data developed in other programs can be output to NavCAD. NavCAD can also be run in other Engineering design process; After inputting the design data into NavCAD and performing analysis, the new optimized hull parameters can be returned to the main program. HydroComp collaborates with major ship software developers to enable NavCAD to run in other systems, and ship parameters can be automatically generated and transmitted. Similarly, users can also call other programs in NavCAD. The format of data exchange is based on standard ASCII code. The main improvement of the latest NavCAD version 3.8 lies in improving user productivity and improving the accuracy and reliability of estimation results. The most eye-catching new feature is resistance prediction based on CT. In previous versions, the estimation method could be used for ship types such as displacement, semi displacement, and sailing ships, and the definition of a ship often required repeated modifications back and forth; In version 3.8, all the resistance estimation methods and hull data of these hulls are concentrated on one screen for input, and the input of parameters can also be done in dimensionless form (such as length/width ratio, width/draft ratio, etc.).