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Marking Your Chart

There are some conventions to marking up your chart. The main reason to use these conventions is that anyone can pick up your chart and know instantly whether the course is true or magnetic.

Course Heading is always marked above the line using 3 digits. If there is nothing following the number then we assume that the course is a true heading. It is a good idea to mark all your course numbers with a “T” for true or “M” for magnetic so there cannot be any misunderstandings.

Distance is marked under the course line using one decimal place. Place the letter “D” after the number so it cannot be confused with any other marking on your chart.

Speed is marked under the line with one decimal and the letter “S” after it. All nautical speed is assumed to be in knots. One knot equals 1.15 MPH.

C 082 M
___________________________________
D 7.4   S 10.3
C= Course
M= Magnetic
D= Distance
S= Speed