Availability should be 100%. FIG. 7 shows preventive maintenance time
distribution of CREW1 with maintenance serviced by two workers. Corrective maintenance
time distribution of CREW2 is identical to FIG. 6. Comparing FIG.6 and FIG.7, it is
concluded that if both preventive maintenance and corrective maintenance workers are
allocated their work respectively, overtime of crew will fairly decrease. It is assumed in
the proposed simulation model of machinery failures that maintenance of nautical
instruments and marine engines is performed in conformity with the above results. This
model can be used to calculate the optimum size of OBM, that is, the number of maintenance
workers required. Thus, this failure and repair model will help determine the OBM activity
and its program according to voyage Scenario. Attribute values of the model is given
following the Scenario, and the simulation study was made which gives the supporting data
which will help determine the framework of field service and OBM according to importance
degree of the failures of hull and marine engine.
4. CONCLUSION
This research aimed to apply the idea of field service and logistics
concept into the maintenance model of ships. We discussed how the maintenance program is
structured. The method is based on the schedule control of ship maintenance program
according to PERT network technique. The benefits and expenses were checked up to make
system transition from traditional dry docking to OBM using PERT/CPM technique. In order
to strengthen the schedule control of dry docking activity and promote OBM, its cost
performance was measured by using data such as construction cost of new ship, the cost of
operation, maintenance and repair cost. In order to step OBM, its incentives to ship
operators need to be established, and the ship designer and builder have to pay more
attention to easier maintenance and repair.
OBM now became routine works of the crew, so that a transition to OBM
from traditional maintenance will progress rapidly, thus how many service personnel is
provided will sooner or later be important problem to be solved. Also, the shore support
system for ship operation will be surely needed. We considered the relation between
manning of ship's crew and maintenance program. Manning with crew of many nationalities,
and many modes of ship owning such as flag-of-convenience ship will also necessarily
modernize the ship maintenance method. Thus, field service concept will be useful for
constructing maintenance program.
The simulation research was successfully applied to compare the
benefits of the two alternatives of ship maintenance. Thus, investigation of actual
conditions of failures in ship is ascertained indispensable. It is necessary to examine
MTBF (mean time between failures) of service parts of every kind and their volume of
inventories, and a length of voyage. On the standpoint, it is feasible for the management
of a steamship company to effectively allocate the limited financial resources by
minimizing ship's life cycle cost.
