🔍 Key Concepts

• Difference in latitude and longitude between the two positions and how to plot them on a Mercator chart or maneuvering board • How to find course made good from the first position to the second using a line of position or simple plotting • Using the time difference and distance between positions to compute speed made good with ( \text{Speed} = \frac{\text{Distance}}{\text{Time}} )

💭 Think About

• First, determine the total time elapsed between 1930 and 2024 in hours and decimals. How many minutes is that, and what is it as a fraction of an hour? • Plot the two positions and draw the straight line from the first to the second. What is the true bearing (course) of that line from the origin point? Is it generally trending NE or SW? • Measure the distance along that line in nautical miles. Once you have the distance and time, what speed does that give you, and which choice is closest?

✅ Before You Answer

• Make sure you convert minutes of latitude directly to nautical miles (1 minute of latitude = 1 NM). • Check whether the latitude is increasing or decreasing and whether the longitude is moving further west or east, to decide if the track is generally NE, NW, SE, or SW. • After finding distance and time, double-check your speed calculation: ( \text{Speed (knots)} = \frac{\text{Distance (NM)}}{\text{Time (hours)}} ).