In this report, is described the result of the questionnaire concerning troubles supposed to be caused by fuels and properties of the fuels, which was implemented by the Japanese Shipowners' Association during the period from Jan. 1981 to Dec. 1981.
The tendency of the troubles observed is almost the same as the result of the questionnaire which, prior to this, had been carried out during the period from 1976 to 1980. But it is peculiarly noted that troubles such as vapour lock in fuel line, cavitation in fuel pumps and level fluctuation of stand pipe were reported.

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The paper briefly describes the works and evaluations on an investigation undertaken for the utilization of low grade fuel oils applied to marine industries in Japan. The future pattern of marine fuel oil quality is considered to be getting worse year by year in view from the world oil supply and demand.
For solving this problem for marine application, the Ship-Machinery Manufacturers' Association of Japan started an activity on this project in 1980 for three years program. The works being carried out are followings;
(1) survey on the quality of marine fuel oils at various ports in the world, such as density, viscosity, conradson carbon residue, sediment, alminum, silica, etc.
(2) survey on the correlation between the quality of fuel oils used and troubles of ship machineries
(3) burning tests of low grade fuel oils (continuous and diesel combustion)
(4) experimental evaluation on fuel oil treatment including the removal of catalitic fines for shipboard equipments such as centrifuges, homogenizers and filters under various treatment conditions
(5) utilization test of low grade fuel oils (250 cSt, at 50°C) for one year operation done by three coastal tankers under actual service conditions.

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This paper reports on the improvements in diesel combustion of low grade marine fuels. The presented data are on the effects of characteristics of the low grade marine fuels on the diesel combustion, on soot reduction by barium compound additives and in the burning of emulsified marine fuels, on the combustion and wear of two cracked type high viscous marine fuels; a fluid catalytic cracked bottom based oil and a visbreaker bottom based oil, in the experimental apparatuses and in a marine low speed diesel engine. The latter experimental results suggests that, in the burning of the fluid catalytic cracked bottom based oil, the silicon particles in the burnt gas are mixed in the sliding surface between cylinder liner and piston rings, the so called, it is abrasive wear, and the wear rates become large.

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This report discuss how to use the new deteriorated marine fuels in diesel engines on the basis of experimental results obtained with a medium speed diesel engine.
The deterioration is caused by the Visbreaker-bottom and F.C.C. Tar as the components of fuels. This will provide effect on the performance and reliability of marine diesel engines. For example,
* Some fuels have poor combustion properties and cause some changes of combustion performance.
* Some fuels have a poor thermal stability.
* Some fuels have a poor compatibility with marine diesel oil.
* The catalyst fine in F.C.C. Tar causes a serious wear of FO pump plunger and cylinder liner without sufficient purification.
* Some fuels foul the lubricating oil.
It seems that almost these problems spoil the superiority of the diesel engines. But the results of our experiments show that the diesel engines are rather insensitive to these changes in fuel despite of its complex structure and restrictions as a combuster.
We expect that the remaining problems to use such fuels are not unsolvable and the diesel engines will be able to retain its superiority.

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Recent degrading of marine fuel oils is going to trouble both operators and manufacturers of the marine boiler systems. So they are being forced to consider the counterplans to cope with degraded fuel oils. MESJ Boiler Research Committee has investigated presumarable characteristics of near future marine fuel oils, and the countermeasures when those fuels are delivered to the existing marine boilers. The investigation results are described in this paper. The most noticeable characteristics of future fuels are the very high amounts of impurities such as sulphur, vanadium, sodium, asphaltene, etc., which cause severe fouling and corrosion problems in the boilers. Therefore careful design considerations should be paid to prevent those impurities attacking the boiler heating surfaces.

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Ship's machinery plant as a whole is to be designed and installed to match the fuel oil utilized therein. This paper presents various practical aspects to be incorporated in designing shipboard systems, external to main engine itself, where utilization of lower quality fuel oil (having viscosity of 3, 500 sec RWI at 100°F or more) is envisaged.
The paper covers fuel oil receiving, storage, transferring, purifying and service installations, as well as lubricating oil system, and takes the form of recommended practices as much as possible; discussing fundamental difficulties encountered in handling lower quality fuel oil, extent of steam tracing, operational considerations, etc.

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Properly engineerd fuel oil pretreatment is an essential element in effective use of low quality fuel on board.
This article is a composition of four independent papers written by specialists of respective field in centrifugal oil purifiers, filters, homogenizers and marine fuel oil analysis.
Recent development and some experimental data are presented.

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Development activities in 14 types of diesel engines both the slow speed and medium speed variety produced in Japan are collectively presented.
Engine types covered are Sulzer, B & W, MAN, Pielstic, MaK, SWD, UE, Akasaka, Niigata, Yanmar, Daihatsu, Hanshin, Matsui and Makita.

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