On the hull form study of Okinawan [Japan] Majian ships

Since ancient times, Ryukyu has developed its own shipbuilding technology. One of the traditional ships is the 'Majian', which had been used for sea transportation around the Ryukyu islands and Japan. The ship is sometimes called 'Yambaru' as well. At the present, there are no actual ships in commercial use, and therefore a very few shipwrights pass down the traditional technology from generation to generation. Historically, it is understood that the shipbuilding technology of the 'Majian' is very much influenced by the Chinese ships called 'Tribute ships' which were used for the voyages between Ryukyu and the Ming and Quing from 1372 to 1876. Such ships were originally built in China and given to Ryukyu. There is evidence that some tribute ships were built in Ryukyu around 1557 by permission of the Ming Dynasty. The technology obtained in those days is thought to have spread out to Ryukyuan shipwrights and was developed to meet the local requirements. In the Marine Cultural Museum in Uruma City, Okinawa Prefecture, large size model ships built by a shipwright Mr. Goeku, who is a living intangible city asset, are exhibited for the public education of their own traditional technology. Furthermore, another large size model was also built by him. The study was conducted by measuring the detail hull form using a Laser Total Station System under the full cooperation of the Marine Cultural Museum and Mr. Goeku. In this paper, the result of the survey is briefly mentioned, followed by the successive technical investigations using the model and theoretical tools for the grasp of hydrodynarmic performance such as resistance and ship motion in waves etc. In relation to the Chinese technology, a comparison is made about the hull form and ship motion in waves. Finally, this type of survey recording an intangible cultural asset by digitizing the traditional ship form and studying the performance by use of modern technology will contribute to pass down the invaluable traditional shipbuilding culture to future generations.