Garmin GPSMAP 235 Sounder Owner's Manual page 114

Thermocline— A layer of water separating warmer water above from cooler water below.
SECTION
APPENDIX
Turn (TRN)— The difference and direction in degrees between the bearing to your destination
E
and your course over ground. The TRN value is used to indicate what direction, and how many
Glossary
degrees, to turn to get back on course.
Universal Time Coordinated (UTC)— The time of day at the prime meridian (0º longitude) in
Greenwich, England.
Universal Transverse Mercator (UTM)— A grid coordinate system that projects global sections
onto a flat surface to measure position in specific zones.
Velocity Made Good (VMG)—The speed you are traveling in the direction of the destination.
Waypoint—A specific location saved in the receiver's memory.
Whiteline—A term applied to the portion of the sonar display which shows the area of strongest
sonar return (typically the bottom).
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