On 4 January your 0800 zone time DR position...

Question 1 of 2707066636eea28f7522a1c51ae15

On 4 January your 0800 zone time DR position is LAT 25°25.0 S, LONG 16°09.0'W. Your vessel is on course 290°T at a speed of 13.5 knots. What is the zone time of local apparent noon (LAN)?

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Question 1 of 27070

On 4 January your 0800 zone time DR position is LAT 25°25.0 S, LONG 16°09.0'W. Your vessel is on course 290°T at a speed of 13.5 knots. What is the zone time of local apparent noon (LAN)?

🔍 Key Concepts

• Local Apparent Noon (LAN) occurs when the Sun is on your meridian (hour angle 0°). • Relationship between longitude and time (15° of longitude = 1 hour of time). • Effect of vessel’s motion in longitude when estimating LAN from a DR position and course/speed.

💭 Think About

• From your 0800 DR longitude, how many degrees (and minutes) of longitude are you from the standard meridian for your time zone? Convert that longitude difference to time. • Starting from 1200 at the standard meridian, should LAN at your longitude occur earlier or later? Think about whether you are east or west of that meridian. • Between 0800 and your approximate LAN time, how much does your longitude change along course 290°T at 13.5 knots? How does that change tweak your first estimate of LAN?

✅ Before You Answer

• Compute the initial LAN estimate using only your starting longitude and the 4-minutes-per-degree rule before correcting for motion. • Estimate the time interval from 0800 to your first LAN guess, then find the change in longitude over that interval; be sure you use the correct longitude component of your track, not the full distance. • After applying the running fix (adjusted longitude), recompute LAN and check that the final time is consistent (close to your previous estimate, within a few minutes).