How many Global Positioning Satellites are required to ascertain a fix position at sea?

To ascertain a fixed position at sea using Global Positioning System (GPS) technology, a minimum of three satellites is necessary. This is because the GPS works by triangulating the position based on the signals received from these satellites. Each satellite provides a signal that contains the time it was transmitted and its location, allowing the receiver to calculate the distance to each satellite by comparing the timestamp.

With three satellites, the GPS receiver can determine a two-dimensional position, such as latitude and longitude, by intersecting the spheres created by the distances to each satellite. However, to calculate altitude and establish a three-dimensional fix, a fourth satellite is required, which is why having more satellites on hand enhances accuracy and reliability. In practice, while three satellites can provide a basic location fix, four satellites ensure the most reliable and precise positional data, factoring in altitude as well.

Thus, the choice indicating that three satellites are necessary highlights the fundamental understanding of how GPS technology operates in determining positions at sea.