Patrol boat is designed not to be slow in its movement on the water surface. To be able to move quickly and agilely, the most important requirement for this type of ship is in its maneuverability. The ship's motion at sea (seakeeping) is influenced by several things, speed, body shape, and the direction of the ship's heading waves. In this study, we analyze the six degrees of freedom, especially on the response of the ship's vertical movement, namely rolling on the sea waves of Seastate 7, especially in extreme weather in the South China Sea. The standard limit used is NORDFORSK 1987 with Light Manual Work Criteria. By entering parameters such as variations in speed and wave angle, such as 0°, 45°, 180° and 270°, then from the graph it can be seen the critical value for each movement. The calculation is carried out with the help of computational software Maxsurf Motions Advanced 20 V8i. The results of this study are the maximum roll movement value that occurs at a speed of 14 knots with a wave angle of 45° with a roll angle value of 6.40o. Furthermore, there is a decrease in the value of the movement along with the increase in the speed of the ship. The minimum roll value occurs when the wave angle is 270° when the ship's speed is 28 knots with a value of 5.69o.

To achieve energy efficiency and emission reduction in the shipping sector use of alternative marine fuel is one of the programs implemented. This study on alternative fuels is an active response to increasingly stringent emission regulations and the limited supply of fossil fuels. In addition, an operational feasibility study is an important thing. The method used in this research is computational fluid dynamics to see how the engine performance, combustion, and emissions when using biodiesel B20 at a constant speed of 2200 Rpm compared to when using petroleum diesel. From the results of the numerical comparison study, the use of B20 compared to petroleum diesel, there was an increase in engine performance the level of fuel consumption was higher. The use of B20 causes CO and UHC emissions to decrease while NOx increases compared to petroleum diesel.

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Natural gas has been a promising demand for several years in Indonesia as a fuel for a diesel engine by converted into a natural gas/diesel dual-fuel engine. However, determining the energy ratio of the diesel and natural gas fuel is important due to the engine performance and emissions which affect the engine safety operation. This study presents the method to determine the natural gas and diesel fuel energy ratio on intake port natural gas injection mode through experiment. A direct injection diesel engine is converted to a natural gas/diesel dual-fuel engine by injecting natural gas into the intake port. The diesel injection parameters are unmodified for the experiment; besides the natural gas injection variations are studied to determine the energy ratio. Moreover, the engine is tested for low to high load conditions. However, natural gas injection duration, pressure, and injection timing variation affect the fuel energy ratio and indicated thermal efficiency (ITE). At low load, the optimum fuel energy ratio and ITE are achieved at a long injection duration (10 ms) and with advanced injection timing. Moreover, at high load, the optimum fuel energy ratio and ITE is achieved at high natural gas injection duration (12 ms), high injection pressure (3 bar), and advancing the injection timing.