š Key Concepts
ā¢ Chart symbols for positions such as fix, dead reckoning (DR), running fix, and estimated position (EP)
ā¢ Difference between a precise position and a predicted or approximated position
ā¢ Standard plotting symbols used in traditional coastal navigation
š Think About
ā¢ Think about which of these positions is usually completely enclosed (for example, by a circle) versus one that is partially enclosed, like with a semi-circle.
ā¢ Ask yourself: which type of position depends on measured lines of position (LOPs) and which depends mainly on course and speed through the water?
ā¢ Consider which type of position symbol is used when you are least certain of your exact location and are allowing for possible error.
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Before You Answer
ā¢ Verify which symbol on a standard paper chart uses a full circle versus a semi-circle.
ā¢ Check which position type (fix, DR, running fix, or EP) is associated with no visual or electronic observations, only course, speed, and time.
ā¢ Confirm from a navigation textbook or plotting guide which position symbol is used when allowing for current, wind, and other unknowns.