Abstract
Manoeuvring prediction is indispensable for the designing stage of ship. It becomes a serious concern that the manoeuvring performance complies with the IMO standard. For medium speed merchant ships such as container ship and PCC, they have the tendency that the advance and tactical diameter become larger by the course-keeping quality too stable, and have a possibility not to comply with the standard. Particularly, at the ballast condition with large trim by the stern, the above tendency becomes stronger. As for fishing vessels, Cb is around 0.6 that is similar to the above merchant ships because of the high Froude number, and has an initial trim in addition to the conventional baseline trim. It becomes very important to precisely evaluate the manoeuvring hydrodynamic forces against the trim.Based on the above background, the authors have made the database of manoeuvring hydrodynamic coefficients for medium speed merchant ship and fishing vessels with one propeller and one rudder system. Then, the regression models which properly presume hydrodynamic coefficients are introduced based on this database.The concluding remarks are summarized below. 1. The linear hydrodynamic derivatives of hull can be well predicted even in the large trimmed condition by correcting Kijima's model that had been predicting a turning circle excessively large.2. The interactive coefficients which have been modeled as functions of principal dimensions of ship are not so affected by them.Particularly, kx, x'H and l'R can be modeled as almost constant. aH and γR are slightly affected by the parameter Cb/(L/B), however the effects are too smaller than conventional models.3. Using the presented new regression models, turning motion and z-manoeuvr are simulated and compared with conventional Kijima's model. As the result, the prediction errors can be reduced to 1/2-1/3 of conventional model.
