Possibility of Tacking Maneuver Operation of Japanese Traditional Sailing Trader "Bezai-ship"

“bezai船”是18世纪至19世纪中期日本典型的航海商人。钻机很简单；单桅桅杆上有一面巨大的方帆，名叫“Bezai-ho”。对帆船操盘手要求有良好的操舵和操舵操作能力。然而，它还没有透露bezai船能执行跟踪操作。本研究旨在通过数值模拟的方法，探讨贝赛船进行系泊作业的可能性。另一方面，直到20世纪初，许多bezai船都使用中国的拖缆装置，日语称为“Shinshi-bo”，而不是Bezai-ho。因此，对这种情况下的粘着性能也进行了研究。通过风洞试验、海试和数值计算等方法，对“别宰-ho”和“新世-bo”的气动性能进行了研究。在海上试验中使用了一艘帆测力船“富津号”，通过它可以同时测量作用在帆上的气动力和帆的形状。利用测得的帆形，用涡点阵法计算了帆力。首先，将其磨损过程的数值模拟结果与改造后的贝济船“南河丸”号海试实测数据进行了对比。数值模拟计算了舰船对实测舵角的响应，给出了舰船的航迹和航行状态参数。计算结果与实测数据吻合较好。然后，对航迹跟踪过程进行了数值模拟。仿真结果表明，该船与“Bezai-ho”系泊作业难度较大。然而，当用“新世-博”代替“别济-豪”装配时，仿真结果表明，该船可以很容易地进行跟踪操作。因此，可以得出结论，贝赛船的船体性能可以与当时的西方高船相比。

"Bezai-ship" is a type of typical Japanese sailing trader in the 18th to the mid-19th century. The rig is simple ; single mast with a huge square sail named "Bezai-ho." The sailing traders are required to have good maneuverability for tacking and wearing operation. However, it has not been revealed that the Bezai-ship could perform the tacking operation. This research aims to investigate the possibility of tacking operation of Bezai-ship by means of numerical simulation. On the other hand, until early-20th century, many Bezai-ships were used with Chinese lug rig, "Shinshi-bo" in Japanese, instead of Bezai-ho. Therefore the tacking performance in this case was also investigated.Aerodynamic performance of the Bezai-ho and Shinshi-bo were studied by means of wind tunnel tests, sea trials and numerical calculations. A sail dynamometer boat Fujin was employed for the sea trials, by which the aerodynamic forces acting on the sail and sail shapes were measured at the same time. Using the measured sail shapes, sail forces were calculated by means of a vortex lattice method.At first, the results of numerical simulation of her wearing operation were compared with the measured data, which were obtained by the sea trial of the reconstructed Bezai-ship Naniwa-maru. The numerical simulation calculates ship response to the measured rudder angle, and shows the ship trajectory and the sailing state parameters. The calculated results coincided well with the measured data.Then, the numerical simulation of tacking operation was performed. The simulated results showed the difficulty of tacking operation of this ship with the Bezai-ho. However, when the Bezai-ship was rigged with Shinshi-bo instead of Bezai-ho, the simulation showed that the ship could perform tacking operation easily. Therefore it can be concluded that the performance of the hull of Bezai-ship could stand comparison with the Western tall ships of those days.