Fig. 2 Failure distribution in 2-stroke engines only.
3. FURTHER DEVELOPMENT
With the relentless march of computers and their operating systems, it became clear to the authors that the original CIMACUSE data input system would need to be changed so that it would run easily under MS Windows. Therefore, in the Spring of 1999, it was decided to develop a new data input system and accompanying database for CIMACUSE. This happened to coincide with a considerable increase in the WG membership by a number of East Asian ship operating companies joining the WG. Subsequently, a special sub-group was set up for the East Asia members who could then meet in their own geographical area.
The new version of CIMACUSE was ready by mid 1999 and has been distributed to all members and the database subsequently readjusted to suit the new system. The data input program is now mounted in each members' computer from three diskettes and a CIMAC Icon can be put onto the desktop to enable rapid entry to the program if desired. To further assist members using it, there are a number of drop-down choices, within the program, where items such as engine designer, engine builder, turbocharger designer and maker, engine type codes and, the affected engine region are concerned. Again, there are no ship names or owner/operators' names, only a code for each entry which is made by the member himself.
4. FURTHER RESULTS
At the time of writing this paper, the database holds information on 826 engines and Fig.1 gives an outline of these with their respective numbers of failures. This would appear to give an unfair situation where 2-stroke engines of the MAN B&W design are concerned. However, it should be noted that few of the members who have reported major fault or failure cases so far, are operating 2-stroke main engines from the Wartsila-NSD stable. That situation will now change as a number of recently joined members are operating more engines from the Sulzer family and we therefore, expect the proportion for the Swiss-designed engines to increase. That situation is also reflected in the lower numbers of Mitsubishi engines shown in the nomograph and we are waiting for those members with the well-known Japanese design to report on them.
It will be noted from Fig.1, that there are a considerable number of 4-stroke auxiliary engines in the database and a breakdown of the major faults/failures is now under way. The small number of 4-stroke main engines indicates that we lack ferry and passenger cruise vessel operators in the WG so far. We hope to see at least some of them joining us in the foreseeable future.
Our power station members have started to enter their cases to the database but more have yet to come in as indicated by the small number of 2-stroke generator engines on the nomograph.
Looking at 2-stroke engines only, an analysis of all major fault/failures is shown in Fig.2. Here we can see the large proportion of hot components involved:
cylinder covers
cylinder liners
exhaust valves and,
pistons (the large majority of the piston, rod, and stuffing box segment is pistons).
It might well be expected that these components will, together, show the largest proportion of the failures as they are immediately affected by what happens during the combustion phase. With cylinder pressures ever increasing and, it seems, heavy fuel becoming lower in quality, we do not see that the hot components will diminish in their proportion of failure cases.
