The quality of fuel oil which uses residuum after refinement of crude oil tends to degrade year by year. Even in this tendency of lowering quality of fuel, fuel oils should complete burning in good condition and release their thermal energy fully within the combustion chamber of marine diesel engines.
The paper describes the experimental study on pyrolysis of residual fuel oils in heating using a gas chromatography and mass spectroscopy analyser (GC-MS) .
The result shows that the pyrolysis and polymerization of residual fuel oils in heating process were made clear. The considerations were also performed on the combustion characteristics of residual fuel oils relating with the substances formed after pyrolysis and polymerization in heating process.

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To improve operational efficiency and safety, an expert system technology has been utilized widely for automating ship's operations. In the present report an attempt is made to develop an expert system for sequential control of a marine diesel engine.
At first the structure of a typical marine diesel engine with several subsystems is briefly introduced. Taking into account of the relations among many components of such subsystems, the procedures of sequential control are discussed. The procedures were described like“If- - -, Then- - -.”and build as the knowledge base in a computer. The knowledge base contains the rules not only for normal conditions but also for troubles.
The reasoning engine of the expert system can select sequantially-proper operations and it can also suggest possible countermeasures in trouble conditions. Finally it is point-ed out that the expert system thus build can be utilized as an automated sequential operating system and also as a supp-orting system for marine engineers.

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Former studies, we showed the characteristics of the squish flow in engines. And we proved that the energy of intake flow was better maintained by reducing the entrance of piston cavity.
This paper reviews about the difference of characteristics of the squish flow by using of three different shapes of cavity entrance. In this work, we investigated the correlation between the pattern of turbulence characteristics of the squish flow and the shape of cavity entrance near top dead center of the power stroke by using of hot wire anemometry. Consequently, the round nozzle type was the best matching with the cavity.

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The experienced crew can diagnose the fuel oil line by the touch on the fuel injection pipe. The first paper discussed the experiment of diagnosing the fuel oil leakage from the fuel pump by the accelerometer fixed on the fuel injection pipe. At abnormal condition, the attenuation time of the signal occured at the time of combustion becomes longer then that at the normal condition.
This paper presents the experiment of diagnosing the fuel injection valve by the strain gage fixed on the fuel injection pipe. The abnormal condition is simulated the lowering of the opening pressure of the fuel injection valve by the adjustment the spring tension of the valve.
The distinctive signal is found at the time of the fuel injection. This signal at the abnormal condition becomes bigger than that at the normal condition.

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The fouling on ship hull and propeller surface by the attachment of sea water organisms has bad effects on the propulsive performance. This causes an increse in the frictional resistance between hull and water resulting in the loss of speed and the increse of fuel consumption.
For the prevention of this marine fouling, anti-fouling paints (AF paints) containing noxious compounds such as organic tin and cuprous oxide have been generally coated.
In our experiment, a new typed nontoxic paint that is in no fear of polluting sea environment is coated to ship hull and propeller surface as a new attempt. This paint is made of a special silicon regin, and has useful physical properties for the prevention of attaching organisms, low critical surface tension.
The experiments using a training ship, a tug-boat, a pleasure-boat and a small fishing boat are carried out for one year.
Obtained results are as follows: (1) The nontoxic paint used in our experiment shows a good effect for the prevention of attaching organisms on the FRP-hull and the propeller surface. (2) Attaching organisms on the film of the paint are easily removed by water-jet washing at the pressure as low as 30-40 kgf/cm2. (3) The adhesive force of barnacles on the film of the paint is extremely small and has no particular relationship with the size of the shell.

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The hull of pleasure-boat and the surface of sea cultivating net are fouled by the attachment of many sea water organisms. For the prevention of these foulings, antifouling paints or antifoulants containing noxious compounds such as organic tin and/or cuprous oxide are coated.
Recently, the dissolving out of these noxious compounds into a sea water has caused the marine pollution in the enclosed coastal seas.
Then, our coating-experiments are carried out by using a nontoxic paint which is made of special silicone resin and is in no fear of polluting sea environment.
The results obtained from two year's experiments applying this new typed paint to a pleasure-boat and a cultivating net, are as follows : (1) The amount of fouling of the coated boat is 75-90% less than that of the uncoated boat. (2) The amount of fouling of the coated net is below half of that of the uncoated net. (3) The attaching organisms on the coated net are easily removed by water-jet washing at the pressure as low as 50 kgf/cm². (4) The physical properties of the paint and the dynamical action of waves on it have remarkable effects on the prevention of the attachment of organisms, and further, the influences of the sunshine and the type or the colour of undercoating paints cannot be neglected.

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