Lesson 19: DR Practice Problems.......

Use chart 12221 TR with 9 degrees West variation and the compass deviation table from Lesson 10......

Practice DR Plot Problems

1. At 1712 your GPS indicates a position of LAT 36°54.8' N - LONG 75°39.8' W. You are on course 319° PMC at a speed of 9.9 knots – what’s the latitude and longitude of your 1800 DR position?

A. LAT 36º 59.0’ N LON 075º 47.3’ W
B. LAT 36º 59.9’ N LON 075º 47.3’ W
C. LAT 37º 00.5’ N LON 075º 47.7’ W
D. LAT 36º 59.3’ N LON 075º 47.0’ W

i. Plot 1712 FIX at – LAT 36º 54.8’ N LONG 075º 39.8’ W.

ii. Draw a projected course or DR track line starting at the 1712 fix in True degrees (convert PMC to True using a variation of 9W and the compass deviation table below).

iii. Now you need to plot your 1800 DR position by first determining RUN TIME in minutes from 1712 to the 1800.

iv. Using a boat speed of 9.9 knots and the number of minutes from the above - find the distance to be run until 1800 in nm using D = (S X T)/60.

v. Take the above distance (from mid-latitudes) and plot your 1800 Deduced Position on the DR track line from the 1712 FIX. Be exact. This point is your 1800 DR Position. Label it as such and determine its latitude and longitude.

More DR problems…..

2. At 1354 your GPS indicates a position of 37º 00.0’ N - 075º 45.8’ W. You are on a course of 088º PMC at a speed of 9.5 knots. What’s the latitude and longitude of your 1500 DR position?

A. LAT 36º 59.9’ N LON 075º 33.2’ W
B. LAT 36º 01.6’ N LON 075º 32.5’ W
C. LAT 37º 01.5’ N LON 075º 32.8’ W
D. LAT 37º 08.2’ N LON 075º 32.0’ W

3. At 0954 your GPS indicates a position of 36º 57.0’ N - 075º 41.0’ W. You are on a course of 119º PMC at a speed of 12.8 knots. What’s the latitude and longitude of your 1017 DR position?

A. LAT 36º 54.2’ N LON 075º 35.3’ W
B. LAT 36º 55.9’ N LON 075º 35.7’ W
C. LAT 36º 54.5’ N LON 075º 35.8’ W
D. LAT 36º 55.2’ N LON 075º 35.3’ W


Answers: 1. B
2. C
3. D