The straight sail, as a propulsion device, was discovered a long time ago. And every time the next generation of boys enthusiastically repeat this discovery for themselves, observing how a dry leaf is rapidly sliding along the surface of a puddle, driven by a fresh breeze. But the oblique sail had to be invented.
From the history
The question of who first invented the oblique sail is as rhetorical as the question of the inventor of the wheel. Most likely, the invention was made almost at the same time in several places at once. It is known that the Europeans borrowed it from the Arabs, and they, in turn, learned about the oblique sail from the Polynesians. This fact is not in doubt - without an oblique sail, Polynesian sailors would not have mastered the Pacific Ocean. He was also known in Ancient China. Attempts to move at a steeper angle to the wind using a straight sail were unsuccessful.
Straight means straight
The movement of a ship under a square sail can be compared to sailing with the current. In both cases, you move where the current is blowing or the wind is blowing. Maneuverability with rudder or stern oar is very limited. Moreover, there can be no question of suddenly turning around and swimming in the opposite direction.
To return the ship along the river back, upstream, in Russia, for example, they used the hard labor of barge haulers. Under the "Dubinushka" they pulled the barges by a long line, moving along the coast themselves. At sea, if the wind was not fair, the sail was removed and the crew members or the oarsmen specially contained on the ship sat on the oars.
In coastal sailing, regular sailing was carried out using the breeze cyclicality of the wind direction. The day (or sea) breeze blew from the sea, at night the coastal breeze filled the sail with the wind from the shore.
A revolutionary invention in navigation
The main advantage and advantage of an oblique sail is that it allows the vessel to move against the wind, maneuvering the tack, that is, substituting one or the other side to the headwind. In this case, the direction of the headwind for ships well armed with mixed sails can be up to 20 degrees from the front.
Speaking about the meaning of the oblique sail, one cannot but point out an equally important innovation in the design of medieval ships - the use of a keel. This invention allowed the ship to be stable on course in strong crosswinds and storms.
The disadvantage of sailing vessels with oblique armament was that tacking required the constant participation of a large number of sailors on deck and on masts in order to throw haffles and yards with sails from side to side. This significantly increased the crew of such a ship compared to a ship on which only straight sails were installed, and it could go for weeks with a fair wind.
