Before, “High-Reliable Ship” was studied, and at that time the term “High-Reliable” might give the marine engineers such imagination that the marine propulsion system was operating without break down and free from maintenance. However, in order to obtain and keep the reliability of marine power plant, it has been very cleared how important it is to reconstruct the method for design and maintainance on the power generator plant for marine propulsion. For example, the electric propulsion system is one of the typical plants realized through new design method which has been appeared recently in the world.
The object of this paper is to propose a unified power plant and then to analyze it through the k-out-of-n system method. Here the power generator plant is unified and it provides the necessary power for ship navigation, that is the propulsion power, necessity power for operating subsystems and crew life on board.
First, the concept of a k-out-of-n system method is presented and then using it, necessary results for analyzing the new power plant are introduced theoretically. Next, the obtained results are applied to the new power plant using the data which can be obtained from the field of the marine power plant. Finally, the analytical method based on the k-out-of-n system is shown to be extremely useful one by illustrating the results, and a new power plant proposed newly is very effective from the viewpoint of reliability.

View full abstract

High speed diesel engines are widely used for coastal fishing boats. The problems on cold starting and white smoke emission have occurred in winter when low ignition quality fuel was supplied. Cold starting tests were carried out at a cold test facility at ambient temperatures varied from 25°C to -5°C, on the fuels of different cetane indexes and both compression ratios of 18 or 15 for a small sized direct injection diesel engine. These three factors had also adverse impact on startability and white smoke emission at cold starting of the engine. The effect that reduced the value of 5 in cetane index was equivalent to reduce the ambient temperature in 7.5°C. Cyclic white smoke formation was directly related to the variation of cyclic combustion instability during cold starting. Every cycle that fails to fire will cause the engine speed decelerating, and cause to produce white smoke. In the case of a compression ratio is 15, it should be necessary above 50 in cetane index values without the starting aids. At warmed-up operation, the engine performances were examined under different cetane index fuels with varying the fuel injection timing. The specific fuel consumption at lower loads was increased with decreasing the cetane index of fuel. However, specific fuel consumption at rated power was in agreement with each fuels of different cetane index if fuel injection timing was adjusted for optimum.

View full abstract

This paper describes the new detecting methods of needle valve lift behavior in diesel fuel injector. Authors detected the needle valve lift behavior by using two types of sensors which are the strain gauge type sensor and the piezo-electric sensor in order to verify the fuel injection characteristic for medium speed diesel engine. It was found that these sensors had enough quick response concerning to both opening and closing timing of the needle valve without modification of fuel injector's structure.

View full abstract

The conventional hydraulic system constructed with source and actuator system has several problems such as surging, vibration or noise. Those are caused of use of hydraulic servo-valve or solenoid valve to change the direction or speed of actuator, and the steering equipment for ship has same problems.
To solve those problems and improve the performance of steering system, the author tried to adopt DDV control steering system which can operate the actuator with controlling the motor revolution directly. This system can be thought to reduce the size of system and save energy, and is going to equip on “Shioji-Maru”, the training ship in Tokyo Uniiv. of Mercantile Marine, to confirm the performance.

View full abstract

The following have been understood from this report.
1. The data of the acceleration noise for 18 PWCs sold in Japan was obtained.
2. The guideline to reduce the noise of PWC which make it meet the regulation or the restriction was obtained.
3. The measured data almost meet the theoretical value about the distance attenuation, but in some area the effect by geographical features is necessary to be considered on the way to drive PWC.
4. The frequency element which originated in the number of cylinders of engine and the number of wings of the internal propeller was shown.
5. The time of the maximum of the acceleration noise did not meet the time of maximum revolution of engine. It is an appropriate way to measure the acceleration noise to evaluate the noise of PWC.

View full abstract

The calculating formulae for short-circuit current are computerized by the shipyards or manufacturers of swicthboard according to IEC363 or others. When installing additional generators or motors, short-circuit current is calculated by computer again. If loss of accuracy can be tolerated, simplification on short-circuit current is given the useful guidance to the owners or users when applied to the confirmation or selection of switchgears. The effectiveness for simplifying short-circuit current at the generator busbars is considered on the basis of IEC 363 which has wholly revised at this time. Simplifying assumptions by direct-axis transient reactance of the generators or others are partly described in IEC 363.

View full abstract