What does "speed over ground" (SOG) measure?

"Speed over ground" (SOG) specifically measures the rate at which a vessel is moving over the Earth's surface, taking into account all external factors, including the effects of currents, tides, and wind. It provides a more accurate representation of the vessel's actual progress towards a destination compared to the speed through water, which does not incorporate the influence of these external forces.

This measurement is crucial for navigation and navigation planning, as it allows mariners to assess their true speed and course relative to the land, enabling them to make informed decisions about routing and timing. By understanding SOG, navigators can better predict arrival times and manage navigational strategies effectively in varying conditions.

Other options focus on different aspects of vessel movement, such as the speed through water, wind speed, and data processing speed, which do not accurately convey the true operational measure of SOG.