This paper desribes that how many diesel engines with multi-cylinders are installed in both propulsive system and power generating station one due to both the surveyed results by the 3rd. Technical Committee of Machinery of MESJ (the Marine Engineering Society in Japan) with 13 shipyards in the west part of Japan and the Database of JSRIC (Japan Ship Reliability Investigation Committee) by lots of field data (more than 11500 failures) during a long propelling hours (more than 7 millions hours).
And a model of redundant power system is theoretically demonstrated by not only the degree of reliability and but also the degrees of mainainability and dependabilty with three kinds of evaluation indices whihc are failure rate λ, man-hour mh and manning index MI. A very usefull expressive measure is proposed as a multivariate evaluation chart (MVC), in which λ, mh and MI can be recognized at a glance. By means of this MVC it would be helpful for us to understand that a redundant system should be not evaluated by not only one index which is reliability λ or maintainability mh but also dependabilty MI which has two senses of λ and mh.
The proposed multivariate evaluation chart MVC could be also confirmed to be very usefull expressive measure because three kinds of evaluation indices can be recognized in the chart at a glance.
2. OUTLINES OF SURVEYED SHIPS AND REDUNDANT SYSTEMS
It is very important for the vessels to have a redundant system of their generating power station which consists of many diesel engine sets with multi-cylinders.
In 1964 and 1999 there were reported on the number of generating sets for each vessel twice by authors (R1) and the 3rd. Technical Committee of Machinery (R2) of MESJ which consists of the 13 shipyards in the west part of Japan. The first paper reported that the average number of generating sets was estimated to be 2.70 [sets/vessel] whose total ones were 102 sets installed parallel system for 12 vessels and triple system for 26 ones respectively about 36 years ago.
Now at the end of 20 century its average number has increased up to 2.90 [sets/vessel], whose details are shown in Table 2-1A, which shows also statistical values of combination of diesel engine sets and their cylinders.
It means that the increased degree of redundant generating system were equal to 0.20 [sets/vessel] during 33 years. Its range were 2 and 5 [sets/vessel], and total survey vessels were 661 ones, out of which 13 ones have had a shaft-driven generator installed during 1997 〜 1999.
These statistical values of the above the cases in 1964 and 1999 satisfies the safty reqirement of the Classification rules, it is noticed that in the later case some part of increased generating power needs the electric power for both air-conditioning machinery and additional electric machines, which are not always necessary for safety of sea-going.
The average number was estimated to be 2.70 [sets/vessel] whose details are shown in Table 2-1B. From the above statistical values shown in Table 2-1B its average number was estimated to be 2.53 [sets/vessel], which concerns with only diesel engine prime mover without turbo-generator or shaft-driven one. Therefore if the later two generators were counted into the statistical one the actual average one might be estimated to be range 2.53 〜 3.5 [sets/vessel], whose actual number of generating sets might to be range 2 〜 5 [sets/vessel] installed during the last two decades 1982 〜 1997.
