| 翻訳と辞書 |
Oar
An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end. Oarsmen grasp the oar at the other end. The difference between oars and paddles are that paddles are held by the paddler, and are not connected with the vessel. Oars generally are connected to the vessel by means of rowlocks or tholes which transmit the applied force to the boat. In this system (known as a second class lever) the water is the fulcrum.
Oarsmen generally face the stern of the vessel, reach as far as they can towards the stern, and insert the blade of their oar in the water. As they lean back, towards the vessel's bow, the blade of their oars sweeps the water towards the stern, providing forward thrust – see lever.
For thousands of years vessels were powered either by sails, or the mechanical work of oarsmen, or paddlers. Some ancient vessels were propelled by either oars or sail, depending on the speed and direction of the wind (see galley).
==History==
Rowing oars have been used since the early Neolithic period. Wooden oars, with canoe-shaped pottery, dating from 5000–4500 BC have been discovered in a Hemudu culture site at Yuyao, Zhejiang in modern China.〔Deng, Gang. (1997). ''Chinese Maritime Activities and Socioeconomic Development, c. 2100 B.C.-1900 A.D.'' Westport: Greenwood Press. ISBN 0-313-29212-4, p. 22.〕 In 1999, an oar measuring 63.4 cm (2 ft) in length, dating from 4000 BC, has also been unearthed at Ishikawa Prefecture, Japan.〔The Japan Times. (February 10, 1999). (Oldest oar unearthed from Ishikawa ruins ). Retrieved on 2008-08-13.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Oar」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|