GPS, or Global Positioning System, is a satellite-based system that allows you to accurately determine your speed and location at sea.

Previously, mariners would determine their location and route by the stars in the sky. Now there are over 30 satellites orbiting the Earth at any one time relaying data about a users whereabouts. Each satellite is positioned at an altitude of 12,550 miles and send regular microwave signals to GPS devices back on Earth.

A minimum of 4 satellites are required to determine an accurate location and speed, working by using trilateration.

Random Fact: Satellites usually orbit the Earth twice per day, if you look up at night and see a slow-moving star - it's likely a satellite!

GPS Global Positioning System for Boats