🔍 Key Concepts

• Running fix using multiple celestial LOPs (lines of position) at different times • Advancing earlier LOPs to the time of the last observation using course and speed made good • Using DR (dead reckoning) to check whether your final fix is reasonable compared to where the vessel should be at 0455 ZT

💭 Think About

• How far (in nautical miles) does your vessel travel between each sight time, given 18 knots? Convert those time differences to distance along course 030°T. • Once you advance the earlier LOPs (Mirfak and Regulus) to 0455, where should the intersection of the three LOPs lie relative to your 0455 DR position? Closer, farther, or wildly different? • Compare the distance between your 0430 DR and your candidate 0455 positions: does the change in lat/long match what you would expect for 25 minutes of steaming at 18 knots on 030°T?

✅ Before You Answer

• Compute distance run between 0430 and 0455 using ( \text{Speed} = \frac{\text{Distance}}{\text{Time}} ). Make sure units are consistent (minutes of time to hours). • Check each answer’s change in latitude and longitude from the 0430 DR: which one is closest to the DR track of 030°T at 18 knots over 25 minutes? • Ensure the longitude change direction (more east or more west) makes sense for a course of 030°T starting from LONG 65°31'W at this latitude.