🔍 Key Concepts

• Time of LAN and Sun LOPs – how a meridian passage (LAN) fix gives you a line of latitude and a longitude line of position (LOP) at a known time • Running fix – advancing a line of position from one time to another along the vessel’s track using speed and course made good • Longitude by chronometer / meridian passage – how the Sun’s GHA and your observed LAN time relate to your longitude

💭 Think About

• First, convert all times (both the 0931 ZT sight and the 1206 ZT LAN) to a consistent reference, including the chronometer correction. What is your time zone offset from GMT/UTC? • Determine how far the ship traveled between 0730 ZT and each sight time using the given course and speed. How do you use that to advance or retire a line of position to 1200 ZT? • Think about what information LAN gives you directly (latitude) and what part of the longitude solution comes from the earlier Sun sight and dead reckoning, then decide which direction (more east or more west) your longitude should have moved from 0730 to 1200.

✅ Before You Answer

• Be sure your chronometer correction (slow 02m 22s) is applied with the correct sign when finding UTC for the sights. • Confirm the distance run between 0730, 0931, 1200, and 1206 at 19.0 knots using ( \text{Distance} = \text{Speed} \times \text{Time} ). Round carefully to tenths of a mile when appropriate. • Before choosing an answer, check whether your final longitude is west of your 0730 DR longitude and by roughly how many minutes of arc; eliminate any options that imply an unrealistic change in longitude over the 4.5 hours at 28–29°N latitude.