Transverse vibration of the frame of slow speed engines has been one of the serious problems so far. With the advent of engines with small number of cylinders, fore-and-aft vibration has also become to attract attention, because its natural frequency tends to diminish approaching the exciting frequency at normal continuous output. This is caused by the increased height due to longer piston stroke together with the decreased length due to smaller number of cylinders as compared with the ordinary type of engines.
In this paper, as an example of such problems, the fore-and-aft vibration and also the transverse vibration of a five-cylinder engine frame are investigated.
The results obtained are as follows:
(1) As for the fore-and-aft vibration of the engine frame, a severe vibration may appear due to an excessive decrease in the natural frequency when the engine is installed on board a ship.
(2) For the purpose of reduction of the transverse vibration, bracings have often been put between the engine frame and the deck of ship's hull. For the fore-and-aft vibration also, bracings are useful.
(3) Reducing the engine frame coupled with the engine-room double bottom to a combination of beams, simulation analyses are carried out to obtain the natural frequencies of the engine-frame transverse and fore-and-aft vibration. The calculated values are considerably close to the test results.

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According to analyses made of the failures of propulsion machinery on MO ships, the cases where engine-room personnel found failures without alarms and stopped or reduced the main engine load by manual operation shared more than 50% of the total cases affecting the ship service. Large parts of monitoring and operation still depend on human senses and manual operation even in a modern automated propulsion system.
The machinery failures were divided into two groups at 6 occurrences/10000 hours under way. Machinery in the upper group requires re-examination in order that improvements in reliability can be made, while the lower group already has considerable reliability.
Most types of machinery have individual failure patterns in the common codes of failure phenomena. These patterns, combined with factors such as temperature, pressure, electric current, working hours, etc. can be utilized as a judgement element in plant performance or condition monitoring for short or long periods.

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In recent years, turbine ships have seldom been built because of the remarkable improvement of thermal efficiency of Diesel engine ships. But, there still exists some room for the formers which utilize coal. However, even in the case of coal firing ships, high thermal efficiency is the crucial point from the economical point.
The turbine ships adopt non-repeat regenerative cycle with usually three heaters. In this cycle, the choice of optimum extraction points is one of the most important problems to maximize its thermal efficiency. Only few studies based on approximative methods have been published on optimization of regenerative cycle with surface-type heaters which are used in actual plants rather than contact-type ones, but their analyses were not thoroughly executed and their modellings not realistic.
In this paper, an exact numerical and two approximative methods are employed to analyse two idealized and one practical schemes of regenerative cycle with surface-type heaters assuming the same assumptions and simplifications as earlier works. First, correct formulae of thermal effi-ciency are led in terms of non-dimensional parameters representing the turbine inlet condition and extraction points. Then, the influences of the number of heaters on the optimum efficiency and extraction points are clarified. Next, the degree of approximation is examined on two approxi-mative methods and the constant enthalpy rise method is proven good. Finally, a practical method to apply the results obtained to the cycle calculation using the steam table is given.

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The studies of mechanism of the scrubbers were carried out by a test plant of IGS. The results of the surveys and the studies were showing as follows:
1) Washing effect of 3% NaGl water was greater than that of fresh water.
2) A few kinds of discharge water were gained. The effluent from the former step scrubber were acid water and contained many sulphur. The water of the after step scrubber were rather clean.
3) The correlation of PH and the total sulphur contents in the effluent water simulated well the character of the actual Inert Gas Systems.

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It has become ordinary to provide a shaft generator with thyristor inverter on 2-cycle low-speed main diesel engine as an energy saving and lavor saving means. It was on M.S. Niels Onstad, a 130, 000 DWT motor bulk carrier, that such generating system was adopted first in Japan in a regular way. This ship's shaft generator has the output of 700 kW, and is driven by chain gears of the 1: 8 step up ratio. It was also a new trial in that ship to use chain as a driving gear of shaft generator. This driving system has been working successfully for about two years since the ship's delivery, and proved a reliable marine equipment. It is expected to be applicable to various equipments. This paper introduces chain driving system for shaft generator with thyristor inverter adopted on the Niels Onstad, and discusses matters to which consideration should be given in designing this driving system, including torsional vibration.

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