sailing boat
A sailing boat is a ship I catch the wind on "sail", and to assume driving force. The sailing boats are classified by the number of the mast and a kind of the sail. There are two kinds of "a square sail" and "the fore-and-aft sail" on "sail". "The square sail" has high efficiency to capture a fair wind and turns to move a long range using periodic wind. "The fore-and-aft sail is inferior in the use efficiency of the fair wind, but I can use wind to blow from the front I leave for the wind more and plow through the waves that is and it depends and am advantageous in that it is easy to do steerage (it is reference with item sail" about a kind of the sail, the principle). I do not understand when the human invented the sailing boat well. A fresco like the ship which I served sail in is had for remains of the Egyptian Nile ravine. It is estimated that this fresco was drawn about 8000 years ago. In ancient Greece and the Roman Empire, the warship was a galley ship of the flat-bottomed boat which used a lot of oars together with sail to make much of movement performance, but the merchant ship was a pure sailing boat. As for these sailing boats, square sail was filled one mast with diagonally for the front and back direction of the ship, but has begun to appear on the sailing boat which had two masts in the Roman Empire of front and back in the first year in A.D. The Arab built a seaborne trade network by the sailing boat that the end extended to China based on a community and a trust system of the Islam from the East Africa around the Indian Ocean, and the Indian Ocean presented the aspect of "the sea of the Islam" (it is after European countries go into Portugal in the 16th century that a figure of power changed). The Arab developed the unique chart and navigation and enabled the night voyage.