many industrial diesel engines are used as the main engine of the ship. Apart from being relatively cheaper, the availability of industrial engine is also very abundant, and the repair process is also not too complicated. However, when viewed from the SOLAS regulations related to the main requirements for a ship propulsion engine, it must also be considered, because it operates at sea, so that ship engines must be tougher than industrial engines, especially related to engine performance when experiencing rolling and trim. The purpose of this research is to test the feasibility of industrial diesel engines being operated on ships. By using a water-cooled single-cylinder diesel engine which is commonly used in small ships. The experimental method was used in this research to obtain optimal results according to the conditions in the field, the engine was made in three variations, namely the normal condition (without inclination angle), the rolling condition of 15 0 , and the trim condition of 5 0 which complies with SOLAS regulations related to the inclination angle. The results of the research obtained torque, Specific Fuel Consumption (SFC), and engine thermal efficiency in various engine variations. The highest torque is in the condition of the 15 0 rolling engine, which is 13.87 N.m. The lowest SFC is in the condition of the 15 0 rolling engine, which is 194 gr/kW.h. and the highest thermal efficiency was also obtained at the condition of the 15 0 rolling engine, namely 44.9%. The higher the engine speed, the higher the engine performance value in rolling 15 0 conditions, and the 5 0 trim conditions experience an increasing trend, but in low rotation conditions (750 Rpm) the performance decreases. Seeing the results obtained, a water-cooled single-cylinder diesel engine can be used as a small boat propulsion engine.

In order to save spaces inside a small-sized fishing boat, the high-pressure flow behind propeller is utilized instead of a special cooling pump to cool the main engine. From the previous study, the system is referred to as the Propeller Flow Cooling System (PFCS). As a continuation of the previous study, the present study conducted more experiments in order to compare the performance of a single and a double intake designs of the PVCS with the same cross-sectional area. The designs with circular and elliptical intakes shapes were measured. The experiments were also conducted at the Circulating Water Channel (CWC) facility. The main parameter which was compared in the experiment and analysis was the flow capacity produced by both designs for various propeller revolution (RPM). The experimental results showed that single intake design has a higher flow capacity than the double intake one which was caused by higher flow losses inside the pipe of single intake design mainly due to higher surface friction as well as an additional elbow joint needed in double intake design. This tendency occurred for both circular and elliptical shapes cases.

To enhance performance of a ship in waves, improvement of its geometry appears to be important and should be treated properly. For this purpose, a practical integrated optimization method is developed to acquire improved ship geometry. Namely the Enhanced Unified Theory (EUT) and the Binary-Coded Genetic Algorithm (BCGA) are integrated together to optimize the ship hull geometry of a basis hull through its Sectional Area Curve (SAC). A modified Wigley model is firstly employed as a basis hull and optimized for some wavelength regions. From the obtained results, the added resistance of modified Wigley model decreases in large amount at the desired wavelength region. Furthermore, optimization with an actual ship e.g. SR-108 is also performed with the aim of illustrating effectiveness of the present method for practical purposes. The obtained results show a large reduction of the added resistance while discrepancy in the steady wave resistance is negligible and the total resistance is confirmed to diminish accordingly.