Sailing Performance of "Naniwa-maru" - A Full Scale Reconstruction of a Sailing Trader of Japanese Heritage

"Naniwa-maru" is a reconstruction of a sailing trader that used to ply between Osaka and Edo, today's Tokyo, in the 18th to the mid-19th century. The rig was simple; single mast with a huge square sail. It was of totally wooden construction in a genuine Japanese manner. The present paper relates to her sailing sea-trial results compared with performance prediction based upon tank tests and wind tunnel studies. According to the trial the ship could reach as high as 70° to weather on her track and the speed then was some 30% of the true wind velocity in a fair sailing breeze. She was swiftest on a broad reach, achieving more than 40% of the wind speed. The said prediction proved to explain the test results fairly well.