As marine diesel engine output increases, the combustion chamber will be put under ever more strain. Recently, the catalyst fines of Bunker Fuel Oil by FCC has seriously damaged moving parts and such wear and tear has reportedly affected the safe navigation of ships.
In order to know the wear and tear of moving parts within the combustion chamber, inspection and maintenance are carried out at anchorage; if wear and tear could be studied on board, at sea, such data could improve engine operations and help to prevent engine troubles.
Mitsui O.S.K. Lines has found, as a result of the continuous monitoring and analysis of cylinder oil drain from large-output marine diesel engines, that analyzing such data will allow the continuous monitoring of the wear and tear of moving parts. Consequently, a reduction in the amount of cylinder oil used will contribute to cutting costs.
During the monitoring process, we have tried in various ways to invent a kit which enables easy measurement on board of the concentration of iron powder within cylinder oil drain. We have been successful in developing such a kit using a magnet. We believe that this kit may also be used for monitoring the concentration of iron powder in actuating oil.
We sincerely hope that monitoring wear and tear will secure the safe navigation of ships.

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This paper describes the influences of fluctuation factors in respect to NOx emissions from medium speed diesel engines.
In Part 1, to examine the NOx-concentration correction formula specified in the Technical Code, the authors conducted yearlong research using two types of power-generating medium-speed diesel engines. The purpose of this research was to identify seasonal fluctuation in NOx concentration.
In Part 2, the authors performed a combustion test to observe NOx concentration by varying supply air temperature and absolute humidity with the single cylinder engine. Of the three factors, absolute humidity has the greatest impact on NOx. This test proved that, when the engine load is high, the required NOx-concentration correction on absolute humidity was about double that calculated by the IMO Technical Code.
This present report takes into account fuel ignitability and other possible factors that may be related to NOx-concentration fluctuation, and conducted additional analysis on the degree of contribution of fuel properties to NOx emissions, based on the yearlong measurement data of cogeneration engines, which was discussed in Part 1.

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Recent large 2-stroke marine diesel engines have been developed for more powerful, longer strokes, lighter mass and in a more compact size. As for main bearings of the engines, the higher degree specifications have been required.
For improving the reliability of the bearing, it has been important to grasp the behavior of the bearing as our first study. Measurement of the bearing behavior was carried out with a 7-cylinder diesel engine under the shop trial test. Measurement bearing was the fourth bearing from the fore side of the engine. The bearing is influenced by continuous combustion of both sides of cylinders, so it is considered that the bearing load during the combustion is severe.
Gap sensors, pressure sensors and thermocouples were installed in the measurement bearing. Journal center locus, journal tilting behavior and oil film pressure under the journal tilting behavior were measured on various operating conditions. As the results, the sharp fluctuation of the journal tilting angle was observed during the continuous combustion on 100% propeller law characteristic. Maximum oil film pressure was also appeared at that time. The vertically projected height of the journal in the bearing by maximum tilting angle was almost equal to the half of the bearing clearance. The maximum oil film pressure was sufficiently less than the fatigue limit of white metal of the bearing. On the other hand, the sharp movement of the journal, which was harmful to the bearing, was not detected at starting of the engine.

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