## 4 Case study and Results
which is characteristic of harbor approaches and internal navigation channels, using the methodology presented in Section 3, and the results obtained on the real ship, are presented in Figure 11.  
As can be seen from the results obtained, the methodology presented in this article for the estimation of the usable power of a ship's main engine for ships navigating in the port approach and the internal channels can be applied for practical purposes. The comparative studies of the calculation and experimental results of the received engine power and fuel consumption factors of the ship showed (LNG standard tanker) that the maximum difference between the calculation and experimental results (real ship and calibrated simulator) was up to 0.23, or, as a percentage, up to 9.3 percent. On the basis of the results obtained, it can be concluded that the methodology presented in Section 3 for the estimation of the fuel consumption of ships in port approach and internal navigation channels can be successfully used for practical purposes and further calculations, for example, for the estimation of generated emissions. Fuel consumption of the standard LNG tankers while sailing (Figures 9 and 10) at the specified sailing distance using LNG and diesel fuel depending on the ratio of the ship's draft and depth while the ship is sailing at a speed of 7-8 knots obtained by calculation and experimentally are presented in Figure 12.  
As can be seen from the obtained calculation results (ship's circulation advance at low depths and ship's main engine(s) factors using the methodology presented in Section 3) and the results of experiments on real ships in corresponding conditions, there is a good correlation between the calculation and experimental results, which allows the use of the methodology developed and presented in this paper for practical purposes. At the same time, it is necessary to appreciate the fact that fuel consumption for ships sailing and maneuvering in ports depends up to 10-12 percent on the qualifications of ship crews and port pilots [15]. Figure 11: Standard LNG tanker main engine power and fuel consumption factors depending on the ratio of the ship’s draft and depth (_T/H_) received by the theoretical method (lines) presented in Section 3, and experiments’ results of the real ship (fuel consumption factor, engine power factor) and calibrated simulator. The methodology presented in Section 3 is used to calculate the emissions. Emission values were calculated using petroleum products (diesel) and LNG fuel. The values of \(CO_{2}\) and \(SO_{x}\) emissions, depending on the amount of fuel used, when sailing from the beginning of the port entrance channel to the turning basin (taking into account the differences in the energy capacity of LNG and diesel) were calculated. When the ship sails at a speed of 7-8 knots and different T/H ratios, the amount of \(CO\), \(NO_{x}\) and \(PM\) emissions of a standard LNG tanker, depending on the T/H ratio, was calculated according to the methodology presented in Section 3, based on engine power, engine operating time and the corresponding emission generation factors presented in Tables 1 and 2. The results of generated emissions are presented in Table 5.  
The fuel consumption and emissions of the vessels to maintain the same speed in channels and other similar locations at low depths were calculated using the methodology presented in Section 3 and verified with simulators and real vessels under similar sailing conditions. As can be seen from the obtained results, the difference between the calculation and experimental results is not significant (maximum difference of 8 percent) and therefore the calculation methodology presented in Section 3 can be applied to the estimation of fuel consumption and emissions of ships sailing in harbors and other channels at low depths.