1. Navigation
NAU 102
Lesson 20

2. From Deduced (ded.) Reckoning
Dead Reckoning
From Deduced (ded.) Reckoning
Abbreviated DR

3. Dead Reckoning Definition
The process of determining present position by projecting course and speed from a known past position.
Or, the process of determining future position by projecting course and speed from a known present position.

4. Dead Reckoning Considers only course and speed.
Does not take into account any other factor.
Leeway (movement downwind)
Current
Steering errors
Compass error

5. Determining course of advance Estimated Time of Arrival
Dead Reckoning
Uses
Voyage planning
Determining course of advance
Speed of advance
Estimated Time of Arrival

6. Approximate location between fixes.
Dead Reckoning
Uses
Keeping track of location in the absence of other positional information.
Out of piloting range.
Overcast sky.
GPS acting up.
Approximate location between fixes.

7. Dead Reckoning Uses Determining outside forces.
Wind
Current
Bad steering
If you know the forces, you can compensate for them.

8. Plan future movements after a fix Compare position to desired location
Dead Reckoning
Uses
Plan future movements after a fix
Compare position to desired location
DR to determine course and/or speed necessary to regain track or avoid a hazard

9. Dead Reckoning DR Symbology Use of standard symbols is important
Anyone else (Captain/Relief) can instantly understand the situation.

10. Dead Reckoning Visual fix – circle Electronic fix – triangle
GPS fix – diamond
Running fix – circle labeled “R-fix
R-fix
Estimated position – square
DR position – half circle

11. Written horizontally for fixes and EP’s Written diagonally for DR’s
Dead Reckoning
Times
Written horizontally for fixes and EP’s
2000
0812
1932
R-fix
1447
Written diagonally for DR’s
1447

12. Dead Reckoning Courses Labeled “C” 3 digits
True degrees unless otherwise marked
Written above the track line
Speeds
Labeled “S”
Written below the track line

13. Dead Reckoning

14. Dead Reckoning Rules of DR Plot a DR:
1. At least every hour on the hour
2. After every fix or running fix
3. After every course or speed change
4. After plotting a single line of position (LOP)

15. Dead Reckoning Constructing a DR Start from a known position (a ‘fix’)
Draw a line in the direction of the course
(Use True directions only)
Calculate the distance to next DR point
(using the Rules of DR)
Using the mid-latitude, mark off the distance
Label!

16. Dead Reckoning

17. Dead Reckoning

18. Between fixes, you may fall off your planned track.
Dead Reckoning
Departure from Plan
Between fixes, you may fall off your planned track.
Wind
Current
Bad steering
From your latest fix, DR to regain track and/or avoid navigation hazards.

19. Dead Reckoning

20. Dead Reckoning

21. Dead Reckoning Fix Expansion
A DR is an approximation of position based on very limited information.
There will always be inaccuracy and positional error in every DR.
The longer the time since your last fix, the greater the error.

22. Dead Reckoning
Be extra vigilant when a navigational hazard falls within your error circle.

23. Alternative format for voyage planning.
Dead Reckoning
Alternative format for voyage planning.
Each turn point (waypoint) is labeled with ETA to the point and distance to destination.

24. Introduction to Navigation
Questions?