DATABASE SYSTEM APPROACH FOR PREDICTING SHIP MANEUVERING PERFORMANCE

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There have been so many fatal accidents which may cause serious marine pollutions and the maneuverability standards is now under discussion at the IMO. Then it becomes important to predict maneuvering performance of ships at the initial design stage. In the present research a database system is investigated for such predictions.The databases of ships' particulars, hydrodynamic forces and maneuvering performance were built up and the procedures to estimate the relations among three databases have been developed. The database of maneuvering performance contains the sea trial results of about 760 ships and this is the most detailed one ever built.To investigate the relation between ships' principal particulars and maneuvering performance, both database were analyzed statistically and the empirical formulae were successfully found for turning abilities. However, it is difficult to find the clear relation between the principal particulars and the directional stabilities.An effort was also paid for finding the relations between the principal particulars and the hydrodynamic forces. It seems possible to estimate the rough relations between both databases. To estimate the maneuvering performance with enough accuracy, however, hull forms, especially of sterns must be taken into consideration. The concept of type ship is shown effective and it is pointed out that the combination of the database approach and theoretical procedures of hydrodynamic force estimations should be investigated.To evaluate the allowable limit of directional instability of ships under human control, simulator studies were widely carried out and the standard of this ability was finally proposed, taking account of the above limit and the possible level estimated from the database analysis. The proposal becomes the standard plan proposed by Japanese government for the IMO.