Estimating the key parameters, block coefficient, and lightship weight is crucial in the initial stages of ship design due to its influence on shipbuilding costs. The weight of the hull, machinery, and equipment, along with their distribution, impacts the hull's strength, deadweight, and stability. Accurate estimates of these weights during the preliminary design phase are essential for defining construction costs as precisely as possible. Another fundamental goal for designers is to shape the ship to minimize resistance while sailing at a specific speed. The block coefficient is a significant factor influencing the ship's form. A direct empirical relationship exists between the block coefficient and the Froude number. Since designers often have limited time in the conceptual or preliminary phases of ship design, the methods employed to determine lightship weight and block coefficient must be reliable, quick, and effective. To address this need, a previous database for three types of merchant vessels: tankers, bulk carriers, and container ships is adjusted. This paper reviews and analyzes existing formulas for estimating lightship weight and block coefficient based on empirical data from constructed ships. Combinations of empirical formulas were tested, followed by adjustments to these formulas, but also introduced new formulas. The paper presents a new preliminary design model utilizing the Generalized Reduced Gradient (GRG) method for determining lightship weight. In contrast, regression and Random Forest methods (RFM) are used for determining block coefficients. The results indicate that this model provides satisfactory results.