The application of water-in-oil type emulsified fuel to marine diesel engines is one of the attractive methods from a viewpoint of NOx reduction. Considering with actual application, it must be known how the water content and environment temperature influence the stability of combustion and engine performance. However, the combustion stability of diesel engine operated with emulsified fuel have not been reported. Therefore, the authors examined the influences of water content ratio (water to gas oil ratio : Gw= 0 -1.19mass) and inlet air temperature (25- 6°C) on the stability of combustion.
As a result, the sufficient combustion stability was obtained when the engine was operated under the conditions with higher load ratios than 1/4 (BMEP=0.26MPa) and lower water ratios than Gw=0.51.

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A welded joint is widely used for bonding structural members and machine parts as well as bolted and riveted joints. When some defects or cracks are detected by visual or non destructive inspections aroud welded regions, a so-called “repair welding” is conducted to compensate the strength of welded structure. Since the weld length by repair welding is generally short, the welded portion is likely to undergo a rapid cooling, thus leading to the reduction of joint strength.
In this paper, a numerical approach using three-dimensional Finite Difference Method (FDM) in the transient temperature field is proposed for evaluating the fundamental characteristics of cooling process of repair welding. The shielded metal arc welding is performed to verify the validity of the proposed numerical method, and the numerical results of temperature distributions on plate surface are also compared with those obtained by infrared thermography.

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To improve safety, local fire-fighting measures in machinery spaces, i.e., the measures for fire-extinguishing before the development of fire, are discussed in International Maritime Organization. In order to extinguish fire in engine rooms, it should be detected in its early stage of development. In view of this, fire detectors in engine rooms should be located at appropriate positions. The purpose of this research is to present a guidance for appropriate location of fire detectors in engine rooms.
This paper presents the results of the investigation of fire casualties in engine rooms based on the reports of Maritime Disaster Inquiry. At first, among 553 casualties on fire and explosion in ships, those of passenger ships and cargo ships having 100 tons of gross tonnage and upward were selected. After that, casualties on fire in steel ships were selected. Finally, twenty seven casualties on fire in engine rooms were investigated in details, mainly from the view point of source of ignition. These casualties showed the following issues:
1. Engine room fires mainly occurred during voyage;
2. Major fuels for ignition were combustible oils; and
3. Major sources of ignition were exhaust lines.
As a conclusion, it is pointed out that the location of fire detectors in engine rooms should be determined by taking into account the out-break of fire at turbo-chargers, exhaust manifolds and flexible joints in the exhaust lines for its early detection.

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