Effect Of Loading Condition On Ship Maneuverability And Its Prediction

The shipping is the main transportation way in which the trade with other countries is at present. The ship has been developed for several generations, and the tonnage is larger and larger, especially for the container, the stowage is over 10,000 TEU for the moment. Because scale of ships and the loading capacity are larger, the ship maneuvering is widely focused on.International Maritime Organization(IMO) has concerned the standard of ship maneuvering, in 1993, IMO adopted interim standards for ship manoeuvrability as Resolution A.715(18). In 2002, the Maritime Safety Committee adopted resolution MSC.137(76) on standards for ship manoeuvrability and definitely come up with the requirement of the magnitude on ship maneuvering, what's more, the government was suggested to carry out the standards. To meet the requirement of the standards, ship maneuvering is evaluated in the initial ship design.The standards is applied to full loading and even keel, hence, the ship maneuvering has to been predicted in full loading condition with even keel. For the oil tanker, the sea test in full loading is done easily, however, for the dry cargo ship, the sea test is only done in ballast or heavy ballast condition, therefore, the method predicting the ship maneuvering has to be studied from ballast condition to full loading condition. In addition, the fuel and the equipped things are consumed, and the cargo has to be loaded and unloaded when the ship sails, which results in the change of the draught and the trim, those will affect on the ship maneuvering. So to ensure the safety, the ship maneuvering in loading condition should be known by the seamen.Firstly, in the paper the mathematical model of ship maneuvering is developed, based on the free running test, the regularization method is adopted to obtain the computated value of the interaction force coefficients between the hull, propeller and rudder, and secondly the measured values of the interaction force coefficients are obtained in captive model tests. The multivariate regression analysis is applied to obtain the regression formula and the prediction formula of the interaction force coefficients, as well as of the characteristic parameters. Thirdly, the comparison of computated values and measured values of the interaction force coefficients is made, and then the characteristic parameters are estimated in the simulation method and are compared between the simulated value and tested value in free running test. Finally, the author analyzed the effect of the draught, the trim and the ship velocity on ship maneuvering. In detail, the main work and research result are introduced in several aspects as follows:(1) A comprehensive review of ship maneuvering in loading conditon is given, as well as various research methods, whose advantages, disadvantages and applicable ranges are also pointed out in detail. And the author integrated the ship maneuvering, numeric analysis, the solution method for inverse problems and the control theory, and made the decision that the regularization method is adopted to obtain the coefficients of ship maneuvering, and that immune genetic algorithm is used as the numerical algorithm of the regularization method.(2) The mathematical model of ship maneuvering is developed in the paper, and the coefficients of the model are introduced. The main factors on ship maneuvering were analyzed. The sensitivity analysis is made to obtain the interaction force coefficients which have a great effect on ship maneuvering.(3) The scheme of captive model test is carried out to measure the interaction force coefficients in different loading condition with the trim by the stern, and then the effect on the interaction force coefficients in different loading condition is studied. At the same time, the scheme of free running test is made, and the turning test & zigzag test are carried out in loading condition with the trim by the stern, what's more, the effect on ship maneuvering is studied in loading condition. As a result, the draught, trim and ship velocity are important factors of ship maneuvering.(4) Demerits of inverse problems are put forward, subsequently the regularization method is used to solve the inverse problems of ship maneuvering, and then the numerical algorithm such as genetic algorithm(GA), immune genetic algorithm(IGA) are proposed to deal with the regularization method. In the research, the author analyzes the merit and demerit of GA & IGA, combines the regularization method with IGA to come up with a new technology which is called regularization immune genetic algorithm(RIGA) to solve the inverse problems. RIGA is applied in the field of ship maneuvering, and showed rapid converging speed and good stability.(5) Based on the free running test, the RIGA is used to obtain the interaction force coefficients in loading condition, and the whole mathematical model of ship maneuvering is developed. The regression formula and the prediction formula of interaction force coefficients, as well as of the characteristic parameters are obtained in the method of multivariate regression analysis, finally, the formula is validated in the sea test or model test.