Simple navigation methods and instruments served European mariners for centuries.
Starting at a known or assumed position, a navigator used simple but reliable tools to track three things:
• The ship’s compass heading.
• The ship’s speed.
• The time spent on each heading and at each speed.
With this information, the navigator could calculate the route and distance the ship had covered and mark a sea chart, if he had one. This method was called dead reckoning. It was used by Columbus and most other mariners of the Age of Exploration.