Navigation / Instrument Acronyms

February 22, 2011

Since users ask about these from time to time, here is the list of acronyms used to denote certain navigation related data items in PolarCOM instruments and elsewhere:

POS – position, that was easy
SOG – speed over ground. Speed of a vessel relative to stationary land.
COG – course over ground. Course of a vessel relative to stationary land.
VTW – speed (velocity) through water. Speed of a vessel relative to water.
HDG – heading. Compass direction into which the bow of a vessel is pointing.
DBK – depth below keel. Water depth measured from bottom of keel
DBS – depth below surface. Water depth measured from surface of water or vessel waterline.
DBT – depth below transducer. Depth as returned by transducer, unadjusted.
AWA – apparent wind angle. Angle of apparent wind as seen from a moving vessel, relative to vessel bow-stern axis.
TWA – true wind angle. Angle of true wind relative to vessel bow-stern axis.
TWD – true wind direction. Compass direction from which the true wind is coming.

VMG – speed (velocity) made good. Speed with which a vessel is moving towards its destination, as measured on a line between current vessel position and destination.
XTE – cross track error. In general, shortest distance from current vessel position to the nearby route leg.
BTN – bearing to next. Compass bearing to the next waypoint enroute.
DTN – distance to next. Distance to the next waypoint enroute.
ETEN – estimated time enroute to next.
ETAN – estimated time of arrival to next.
DTD – distance to destination. Distance to the final point of multi-leg route. Measured along the route.
ETED – estimated time enroute to destination.
ETAD- estimated time of arrival at destination.

ROT – rate of turn.
RDA – rudder angle
SDA – set and drift angle. Used in combined set & drift instrument.
SDD – set and drift direction. Used in combined set & drift instrument.

Any of the direction acronyms above may have a suffix of ‘M’ to denote that they are in degrees magnetic. Without this suffix, assume degrees true. I.e. HDGM vs. HDG.


New “orange” night palette for PolarCOM

March 5, 2010

I am trying to emulate the look of my old LCD nav. instruments. Is this red/orange glow warm enough?