A sailor can manage a ship better with rudders and move the ship. Larger sails were also moveable so they could change direction and speed.
because if the sails didn't work you would still have the rudder in the back and you would have to control it another way
Caravels are ships! They used triangular sails that, unlike traditional square sails, allowed ships to sail against the wind. By replacing oars on the ship's side with rudders at the back of the ship, the Portuguese also greatly improved steering.
The technology in the 1400-1500's made ships better for sailing by the use of rudders, moveable sails, and larger ships. Navigating became better through the use of the astrolabe and better compasses. Mapping also was better.
Sailing ships had rudders at the stern.
Sailing ships must have rudders. Columbus's ships were no exception. There is a nice picture of a nao at the link. The Santa Maria, The flagship for his voyage when he discovered the new world, was this type ship. The Niña and Pinta were caravels. They also had rudders.
Fifteenth century ships, such as those Vespucci sailed on were large, and constructed of wood, with numerous billowing sails. The ships were sometimes reinforced with metal to make them more seaworthy. These ships were highly dependent upon wind being strong enough to maintain constant sailing, yet not too strong as to damage the ships.
stern-post rudders
No the Caravel had a lateen and a square sail and was steered by rudders. The lateen sail aloud it to sail against the wind
"Square sails" which are not really square, were/are referred to as four-cornered sails.
stern-post rudders
yes
Ships and navigation improved in the 1400 and 1500's. Ships got rudders and moveable sails. With these they were able to move better and catch winds rather than just sitting waiting for wind. Tools for navigation improved as well. The astrolabe was invented to allow the use of longitude and latitude settings. Ships were also bigger.