🔍 Key Concepts

• Relationship between longitude and time difference from local apparent noon (LAN) to Greenwich Mean Time (GMT) or zone time • Effect of vessel’s east–west motion on the time of LAN (movement toward or away from the meridian) • Conversion between degrees of longitude and time (in minutes)

💭 Think About

• First, if the vessel were stopped at the given longitude, what time (in zone time) would you expect LAN based purely on longitude? • Next, how many minutes of longitude will you gain or lose in the east–west direction between 0830 and a first rough guess of LAN, given course 119°T and speed 20.0 knots? • Is the vessel moving toward the meridian of LAN or away from it, and does that make LAN occur earlier or later in zone time compared with the stopped-vessel case?

✅ Before You Answer

• Determine the correct zone description (ZD) for longitude 129°16.0'W and convert between GMT and zone time consistently • Use 15° of longitude = 1 hour (or 1° = 4 minutes) to convert longitude and motion into time corrections • Separate clearly the static LAN time from longitude alone and the dynamic correction for the ship’s motion before choosing an answer