Monday, October 29, 2007


Step 1 Enter the date.

Step 2 Go to " THE NAUTICAL ALMANAC " and use the time of meridian passage for 24
January 1981.

Step 3 Set up universal plotting sheet
Plot 0700 DR position and DR ahead to 1212
Example: 1212 - 0700 =
5h 12m at 12 knots = 62.4 miles

Step 4 Enter your DR longitude for the time of meridian passage you used from the almanac
( 1212 ).

Step 5 Enter the nearest standard meridian.

Step 6 Calculate the difference in arc between the standard meridian and your DR longitude.

Step 7 Convert the arc in step 5 into using the " Conversion of Arc to Time " from the Nautical

Step 8 Now apply the time correction to the time of meridian passage from the almanac.
Because we are west of our standard meridian,we must add the difference. By applying
this correction you will have the time of LAN at the meridian for your DR position. This is
called the first estimate of LAN.

Note: if your clocks are set to daylight savings time ( DST ) add one hour to your zone
time or use the standard meridian that your clocks are set to.