Overview
The sternpost rudder could be used to steer larger ships and allowed ships to sail safely in rough seas. During the 1400's, shipbuilders began to produce ships four times as large as any built before. All these ships had a rudder, and most had three masts and at least three sails. By the late 1400's, navigation instruments such as the mariner's compass, which allowed voyagers to navigate their ships without observing the positions of the moon, stars, and planets, helped make possible the great voyages that led to the exploration of the New World.
Excerpt adapted from the "Invention" and "Transportation" articles, The World Book Encyclopedia, © 1999