| ACo: |
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Altered Course. This is a standard short hand format that is commonly used in logbooks to confirm a change in course. |
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| COG: |
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Course over the ground This term describes the ground track or the proposed ground track of a vessel. |
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| DMG: |
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Distance made good. Used to determine the actual distance a vessel has travelled in a straight line when tacking. |
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| DR: |
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Dead reckoning position. A position found using speed, time and a heading or heading and distance run.
Not considered accurate. |
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| DTW: |
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Distance to waypoint. The distance to the next waypoint or destination. |
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| EP: |
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Estimated position of the vessel. Used when a position is worked out from the course, speed and leeway. |
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| ETA: |
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Estimated time of arrival. |
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| FIX: |
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An accurate position of the vessel. |
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| GNSS |
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Global Navigation Satellite System. Commonly called GPS, there are however a variety of systems in use. |
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| GMDSS |
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Global Maritime Distress and Safety System. The network of satellites and ground stations used to detect transmissions from an EPIRB. |
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| GT: |
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Ground track. A line marked drawn on the chart denoting the proposed or completed course over the ground of a vessel. |
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| XTE: |
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Cross track error. Used to denote how far a vessel has strayed from the plotted ground track |
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| SOG: |
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Speed over the ground. Describes the speed of a vessel over the ground including the effect of tide. |
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| TMG: |
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Track made good. Gives the average course over the ground a vessel has made from the start point it's current position. |
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| TTG: |
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Tme to go. Time to the next waypoint or the destination. |
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| WP: |
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Waypoint. A small box plotted along the propesed course of a vessel. Usually marking a destination or change of course. |