🔍 Key Concepts

• Local Apparent Noon (LAN) occurs when the Sun crosses your local meridian (is due north or due south on the compass). • The relationship between longitude and time: 15° of longitude = 1 hour of time difference. • How to advance your DR position from 0830 to the approximate LAN time using course and speed.

💭 Think About

• First, estimate what time the Sun should cross your meridian based on your longitude alone, ignoring motion of the ship. How many hours ahead of or behind 0000 at Greenwich would LAN be at about 73°E? • Next, consider that your ship is moving west on course 280°T. Does moving west make LAN occur earlier or later in zone time than it would if you were stationary? • Compute how far (in longitude) you will move between 0830 and each answer choice using speed and course, then decide which time makes your DR longitude line up best with the meridian passage of the Sun.

✅ Before You Answer

• Convert speed 19.0 knots and time difference (in minutes) into distance in nautical miles using ( \text{Distance} = \text{Speed} \times \text{Time} ). • Convert that distance along your track into change in longitude, taking into account your latitude (use ( \text{departure} = \text{distance} \times \sin(\text{course}) )). • Check whether your final DR longitude at LAN matches the time when the Sun would be on that meridian based on the 15° per hour relationship.