Field experiences with present offshore onboard computer systems have made evident that significant limitations do exist. This first generation software performs analytical calculations with dubious accuracy and requires a high degree of computer literacy for proper use. Attention is focused on their shortcomings and on specific approaches to overcome these problems in second generation development efforts. Major safety improvements which can be gained by incorporating "expert system" programming are presented. In future upgraded systems expert programs would help insure an experienced rational performance of emergency procedures.
The software and hardware systems, presently in use, were the first systems of significant magnitude to be installed on commercial marine vessels. These "first generation" systems were a tremendous advancement above "hand calculation methods" and for the most part have proved to be a valuable rig tool. The time has come to improve our present "infancy stage" technology with "second generation" hardware and software to provide increased performance and safety.
A large number of improvements are warranted in the area of basic analytical techniques. Combining these techniques with recent advances in "expert system" programing has the potential to significantly improve shipboard advisory software.
Programs for semi-submersible drilling rigs are the most complex example of first generation software. These programs will be justifiably the primary focus of this paper. Software techniques used on semis can be applied to improve safety on many types of marine systems. This type of software with expert systems could be particularly valuable on military vessels with regards to damage control techniques.
The topic of first generation systems alone is an extensive one. This paper will only briefly describe the major components utilized in software packages presently implemented on world wide semi-submersible drilling vessels. The reader is encouraged to consult other sources for further details of current software packages which are tailored to a variety of different vessels and rigs.
Tasks and systems which currently benefit from shipboard computing are;
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Daily stability Calculations
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Mooring System and operations
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Motion Analysis
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Riser System
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Inventory Control
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Personnel and Business
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Management
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Maintenance Records
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Records Modules
The most frequent calculation performed at sea is the" Daily Stability Evaluation". This is a very tedious procedure, consisting of weight and moment summation in all three dimensions for all weights and forces imposed on the vessel. By computerizing these calculations and automating data entry the time savings and the improvements in accuracy are dramatic.
Computations supporting the Mooring system are fairly complex and have several different sets of equations. Each set has its own valid domain depending on tension, payout, waterdepth and line properties. Present systems require that the shipboard mooring technician be capable of executing the proper computer programs and interpreting the results. They are assisted with published table information to help enter data and obtain a suitable solution from the on board computer system.
