## 4 Case study and Results
The mentioned ship's advance testing results are presented in Figure 7. In all cases, a rudder angle of 25 degrees was adopted (to leave a margin of maneuverability). Tests of real ships for simulator calibration were performed as follows: bulk cargo ship--three ships; container ship (9000 TEU)--two ships; container ship (19,500 TEU)--one ship. The \"Tables of maneuvering elements\" available on the ship's bridge were also used. With the help of a calibrated simulator, at least 10 tests (for G class container vessel--10 tests; for 9000 TEU container vessel--12 tests; for 80,000 t bulk cargo ship--12 tests) of each mentioned ship were carried out. In the simulator, we selected ships from the simulator library which were analogous to real ships with which real experimental tests were performed in terms of type and parameters. The differences, although minor, were mostly due to differences in draft and displacement. For example, the simulator library contained a G-class container ship with an average draft of 14.0 m, while the real ship had a draft of 13.7 m. In order to unify the obtained results, it was necessary to calibrate the simulator, i.e., coefficients of the relationship of the received simulator data with the real ship. In practice, for such simulator calibration, one or two datapoints of a specific parameter of a real ship were sufficient. In the article, there were at least 2-3 real results for specific parameters of specified ships, and up to 7-12 such real ship test results were used for individual ships. Figure 6: Ship’s circular trajectory details. The accuracy of the real ship test results obtained, necessary for research and simulator calibration using the RTK system, was: ship location--up to 0.1 m; ship speed--up to 0.1 knots; ship angular rotation speed--0.2 degrees per minute. When using the DGPS system, the accuracy of the received data consisted of: the location of the ship--up to 0.5-1.0 m (depending on the distance to the base station); the speed of the ship--up to 0.2 knots; the angular speed of the ship--up to 0.5 degrees per minute. The study was conducted as presented in Section 3 using the full mission simulator SimFlex Navigator [40] and using real similar ships for experiments. All received data were filtrated by a Kalman filter [53] and the differences between calculated, simulated and real ships' experimental data were analyzed. The results obtained from the advance calculation and experiments (Figure 7) show that the calculation results using the methodology presented in Section 3 are in high compliance with the results of the real ship experiments and the simulator results. The results of calculation and experiments (obtained on real ships and with the help of a calibrated simulator) of ships' advance in circulation at a rudder angle of 25 degrees are shown in Figure 7, and the differences (accuracy) at different _T/H_ ratios in meters and percentages from the experimental results are shown in Table 4.  
The power changes in the main engines of the ships, due to hull longitudinal speed, and additional resistance in shallow waters were calculated according to the methodology presented in Section 3 and verified using a calibrated simulator and the results of real ship experiments under similar conditions (Figure 8). At least eight types of ships were used to determine the power factor of the ship's main engine, depending on the ship's draft and the depth of the navigation channels, for conducting research and calibrating the simulator. During the experiments, equipment on the ship was used: ship echo sounders were used for depth measurement, the accuracy of which was up to 0.1 m, and the accuracy of the power of the ship's main engine(s) was up to 2% of the engine(s) power. During experiments, the fuel consumption of the real ships was measured by existing sensors in the ship's engine room, the accuracy of which was up to 2-3% of the amount of fuel consumed, and instantaneous fuel consumption sensors, the accuracy of which was about 4%. All data were recorded automatically.