The task of this paper includes the assessment of the resistance of a tanker for the transportation of petroleum products with a carrying capacity of 8,500 tons. In the paper, the main dimensions of the ship for the transportation of petroleum products with a carrying capacity of 8,500 tons were selected using the MARAD systematic series of ship models. Then the ship form H was defined, which was selected from MARAD. Furthermore, below is a sketch of the ship's line in the Auto Cadu program. The outline of the ship's lines was created using the specified dimensionless shape coefficients in the tables from MARAD, which were later adjusted to the true dimensions of the ship for the bow and stern of the ship. In the final paper, the coefficient of fullness of truth was assumed, which is C_B=0.85. After drafting the line of the ship and the defined form of the ship, a resistance calculation was made for the selected speed range for a fully loaded ship and a ship in ballast condition. The results of the calculation of the ship's resistance are presented in tabular and graphical form. The final chapter presents the results of the resistance calculation according to the Holtrop-Mennen method, which were obtained using the NavCad computer program. NavCad is used to assess design and predict drag and propulsion for vessels from fast coastal patrol boats to the largest combat and support vessels. The results obtained by the numerical calculation of the resistance of the tanker were compared with the results of the calculation of the resistance of the tanker according to the Holtrop-Mennen method. After comparing the results, the conclusion is reached that the results of the numerical calculation of tanker resistance estimation are satisfactory compared to the results of the calculation of tanker resistance estimation according to the Holtrop-Mennen method.