About 72% of engine troubles of ships that Marine Accident Inquiry Agency had decided from 1996 to 2005 are related to fishing boats. Moreover, almost half of the engine troubles of fishing boats are caused by the lubricating oil system. The experiments were made to reduce the engine troubles of the fishing boats by developing the device based on the lubricating oil system of the fishing boats in this research； the functions of the filters when impure substance got mixed in the lubricating oil and the flow rate change of the lubricating oil as the filters were blocked were demonstrated. The results of the experiments are given as follows : (1) The amount of the removable impure substance got mixed in the lubricating oil depends on the kinds in the used filters through the experiments. (2) The engine trouble can be reduced when the impure substance which got mixed in the lubricating oil is properly removed by agitator which is installed in the lubrication sump tank to stir the impure substance which got mixed in the lubricating oil constantly.
fishing boat
reduction of engine trouble
lubricating oil system