2. 3 The man-hour by the difference of ship
The difference of ship is effected on the route, operation time, a sort of operating, the engine plant and also related auxiliaries. Those are effected to the change of the man-hour. Occurrence situations in terms of ship are shown in Table 3.
2. 4 The man-hour by the difference of main engine out put
The difference of main engine output is decided an outline by the size, displacement, ship speed, etc. They exert an influence on the capacity, complexity, a kind of engines, styles, heat load to a man-hour.
It is shown Table 4 as occurrence situation, in terms of main engine output similarly Table 3 in each items.
3. FACTOR THAT EXERTS INFLUENCE ON CORRECTIVE MAINTENANCE TIME
There are many factors that exerts influence on a corrective maintenance hour as follows. However, it is not easy to predict a maintainability.
1) Corrective maintenance hour is composed of the sum in investigate hour for repairing, cause survey hour, recovering hour and reconfirmed hour for recovering places.
2) The cause that exerts influence on corrective maintenance hour are able to classify in the following two items.
[Physical causes]
Ability of abnormal detection are depend on several factors like an efficiency of test device/self-diagnostic function, diagnosis procedure, easiness of instruction book or repairing manual, accessibility of trouble points, workspace and adjustment area. Furthermore, there are easiness of the exchange in component level and parts level, complexity of the equipment, the quantity of the method, attaching method, weight, structure of difference by recovering.
[Human cause]
There are some human causes like an easiness of extent physiological parameter (physical strength, durability, attention, concentration), number of persons, communication of experience/knowledge, education level, training period, skillfulness of maintenance personnel.
3. 1 Investigating Period:
1) Feb. 1982--Apr. 1996 Committee on Ship Reliability Investigation, Ship Research Institute[2]
Diesel Ship: 184 vessels total data 93249 cases
2) Mar. 1993--Mar 1999 Collecting data on trouble report on actual working vessels[3]
Diesel Ship: 50 vessels total data 890 cases
3.2 Definition of Term
Definition of term are shown as follows.
l) failure rate (FR)=total failure number *1000/operating hour (hr): case/10000 hrs
2) maintenance man hour (MH) =man * maintenance hour (hr) per case: mh/case
3) mean time between failure (MTBF) = operating hour (hr)/total failure number: hr/case
4) manning index (MI) =FR * MH: mh/1000 hrs
5) operating hour=running hour (hr) +port rest hour (hr): Remark: FR definite each 1000 hrs depend on approximate operating hour per one voyage by MO ocean sea going ships.
4. MAN-HOUR AND OCCURRENCE CASES
Figure 1 is all average of the distribution diagram of ten systems which is drawn the occurrence cases per one man-hour as a vertical line and the each man-hour per case as a horizontal line.
Fig. 1 Maint.Condition
