Soot emission is one of the most serious disadvantages of diesel engines. Although it is an urgent need to find an appropriate method to reduce it, no practical means have yet been developed nor has the mechanism of soot formation been made clear enough. The authors have concentrated on an optical measurement named the “transmissive light extinction method” to investigate the soot behavior in a diesel combustion chamber.
In the 1st report, the theoretical principle and its reductions to practical methodology were presented, as well as discussions on applicability of the method to diesel combustion flame.
This paper reports on an attempt made to apply the transmissive light extinction method to an actual measurement of soot particles in a diesel combustion chamber.
First, an experimental engine was developed, which was installed with a disk shaped combustion chamber with quartz windows on its both sides to allow optical access. It was also equipped with a 2nd stage piston, over the original 1st stage one, which was designed for non-lubricated operation to prevent oil mist from intruding into the combustion chamber.
With the experimental engine, measurements of soot particles in actual diesel combustion flame were performed. The progress of the soot density with time was successfully obtained, showing a quick generation of soot particles soon after the initiation of combustion, and a considerable amount of soot formation in later part of diffusion combustion period.

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Machinery Plant Committee Group III reviewed and partly altered the original standard established in 1971.
The standard gives standard design, calculation method such as current density and service life, and fitting method of sea chest protective zinc.

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Some factors relating to the design and fitting of stern tube bearings and their bushes analyzed on the basis of shipbuilders' standards and their actual performances have been summarized in this paper.

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According as world business recession and excess of ship bottoms, the shipping agents became unprofitable, therefore they request cheaper heavy fuel oil for their vessels.
High viscosity residual marine fuel oil produced by new petroleum refining plants puts great difficulties in treatment system of marine diesel engines.
This paper explains on over 2 steps purificatory system and 2 steps pressure supply system to cope with residual heavy fuel oil.

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Recently, many studies have been conducted for stern tube seals, though which their performance has been considerably improved.
In this course, number of troubles on stern tube seals caused by the damage of sealing rings or liners have been reduced compared with those by other causes such as the catch of fishing nets and ropes. The aft stern tube seal is usually covered with a propeller rope guard to protect the seals from fishing nets and ropes. The fishing nets and ropes caught by the propeller blade, however, would easily coil around the liner through the gap between the propeller boss and rope guard.
Some improved rope guards were designed to prevent the coiling of fishing nets and ropes around the liner and then the performances were examined. It was found from the examination that a new idea “Net Protector” is very effective to protect the stern tube seals from fishing nets and ropes.

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Generally the specific fuel consumption of electric generator diesel engines, which are normally smaller, are more than that of propulsion diesel engines. So, it is said that shaft driven generator systems is effective to reduce the fuel consumption of ships.
By the way there are wide variety of fishing methods and different types and many sized fishing boats. Power output of propulsion engines and generators of fishing boats varied in accordance with the kind of fishing, and their load varies widely by the operating condition.
So, author selected following seven model fishing boats from the so called medium-size fishing boats to compare fuel economy of the shaft driven generator systems with that of the auxiliary engine driven system.
1. Squid fishing boats (99GT)
2. Skipjack pole and line fishing boats (79GT)
3. Tuna long liners (79GT)
4. Tuna long liners (99GT)
5. Salmon drift net boats (97GT)
6. Small offshore trawlers (65GT)
7. One boat purse seiners (80GT)
And author also selected following two systems as the shaft driven generator systems of the above boats.
1. Direct drive system (propulsion engine is running constant speed and boat speed is controlled by controllable pitch propeller.)
2. Thyristor/inverter system
Model operating patterns of these fishing boats during one year were established and calculated their fuel consumption on several generator driven system.
Direct drive system was found ineffective for fuel saving except salmon drift net boat and one boat purse seiners. Thyristor/inverter system obtained 0.5-2.0% fuel economy. However in consideration with the initial cost, for medium-size fishing boats, shaft driven generator systems were not economical in comparison with auxiliary diesel engine driven generator system.

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