104
Speed Over Ground (SOG): Speed Over Ground is the measurement of the boat’s
progress across a given distance, and is the speed measurement provided by GPS. An
alternate, Speed Through Water, is provided by a speed paddlewheel, and is the
measurement of the flow past the boat, which may vary depending on current
speed and direction. Speed Over Ground is optimal for navigation because accurate
destination times can be derived from this measurement. Humminbird® products
allow for input and display of both speed measurements.
Time To Go (TTG): Time To Go is the estimated time required to reach the destination
waypoint. TTG is calculated using the SOG and DTG. See SOG and DTG.
Track: A Track is a series of saved points that define the past path of the boat. These Track
Points are saved at regular time intervals. Tracks are a useful and quick method to see
where you’ve been, and an easy guide to follow to get you back to the starting point.
Generally, all GPS units have a limited number of Track Points that can be saved before the
unit runs out of memory and begins erasing the first track points saved. Because of this,
the user can adjust the Track Point Interval menu to increase the amount of time between
when points are saved, and thus extend the distance covered by a track. Tracks can also
be permanently saved to memory, and re-displayed at the user’s option.
Track Line (TRK): The Track Line is the desired line of travel between two waypoints,
and represents the most efficient path between the two points because it is a
straight line. The TRK is measured in degrees (i.e. 321°, where 000° is North, 090°
East, 180° is South, 270° is West). See Cross Track Error and Course Over Ground.
Trackplotter: Trackplotter describes a navigation device that shows Present Position,
along with Track, Waypoint, and Routes, but NO MAP in the background. See Chartplotter.
Trolling Grid: Trolling Grid is a Humminbird® feature that displays a precise
reference grid around a waypoint. This grid is used as a guide pattern for trolling
around a specific area to assure a more efficient and complete coverage of that area.
Trolling Grid resolution be changed by zooming in or out on the chart. The Trolling
Grid can also be rotated on the display to orient it for optimal boat course for wave
and wind conditions.
UTC: UTC is an acronym for Universal Time Constant. UTC is the “standard time” used in
navigation, and is the local time in Greenwich England. (UTC is equivalent to Greenwich
Mean Time (GMT)). To display the correct Local Time in a Humminbird® GPS unit, the
user must use the Local Time Zone menu and select the time zone (i.e. EST, CST).
WAAS: WAAS is an acronym for Wide Area Augmentation System. WAAS is
