How do you calculated approximate lightship data?

Approximate lightship data is calculated by determining the weight and distribution of the vessel's structure, equipment, and systems when it's empty of cargo, fuel, and crew. This involves estimating the weight of the hull, machinery, and onboard systems, then summing these values to establish the lightship weight. Additionally, factors such as the vessel's design, materials used, and regulatory requirements are considered to ensure accuracy. Finally, naval architects may use empirical formulas or software tools for more precise calculations based on similar vessels.