Dead Reckoning
gud eve... i need you help with this. SHIP AT 0800 OCT 10 2011 LAT 9 2 N LONG 116 49.5E TRUE COURSE 38 SPEED 16 KTS FIND DEADRECKONING POS. AT 1600 OCT 10 2011
Solution:
Step 1. Get the steaming time.
Time of arrival = 1600 10 Oct
Time of departure = 0800 10 Oct
8 hrs is the steaming time
Step 2. Solve for the distance traveled for 8 hours.
Distance = Speed x time
= 16 kts x 8 hrs
= 128 nautical miles
Step 3. Solving for Dlat.
Dlat = Cos 38° x 128 nm
= 100.86 nm
÷ 60 to convert it to degrees and minutes
Dlat = 1° 40.86' N North because the ship is northward
Step 4. Add Dlat and your latitude at position 1 to get the latitude of your new position.
Latitude 1 = 9° 2' N (Add because same name)
Latitude 2 = 10° 42.86' N
Step 5. Solving for the departure and Dlo.
Departure = Sin 38° x Distance
= Sin 38° x 128 nm
= 78.80 nautical miles
÷ Cos 10° 42.86' to get Dlo. But if in equator, Dep = Dlo
80.2 nm
÷ 60 to convert it to degrees and minutes
1° 20.2' E is the Dlo
Step 6. Solving for the new longitude.
Long 1 = 116° 49.5' E
Dlo = 1° 20.2' E same sign; add
Long 2 = 118° 9.7' E
So the new position of the ship is 10° 42.86' N, 118° 9.7' E.
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