A vessel at LAT 21° 32' N, LONG 160° 30' W,...

Question 1 of 2707066636eea28f7522a1c51b7c6

A vessel at LAT 21° 32' N, LONG 160° 30' W, heads for a destination at LAT 30° 00' N, LONG 150° 00' E. Determine the true course and distance by Mercator sailing.

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Question 1 of 27070

A vessel at LAT 21° 32' N, LONG 160° 30' W, heads for a destination at LAT 30° 00' N, LONG 150° 00' E. Determine the true course and distance by Mercator sailing.

🔍 Key Concepts

• Mercator sailing: using difference of latitude and meridional parts to find course and distance • Converting longitudes West/East across 180° and finding the difference of longitude (DLo) correctly • Using the relationship: tan(Course) = DLo in meridional parts / DLat

💭 Think About

• First, convert both positions to the same hemisphere of longitude and carefully compute the algebraic difference of longitude. Are you crossing the 180° meridian? • Decide whether you should use mean latitude or meridional parts for Mercator sailing. Which one fits this method? • After you compute the course angle from your triangle, think about the quadrantal location: is the course generally NW, NE, SE, or SW from the starting point?

✅ Before You Answer

• Make sure your difference of latitude (DLat) sign (north/south) matches the change from 21°32' N to 30°00' N • Confirm your difference of longitude (DLo) accounts for crossing the 180° meridian (from W to E) and is expressed in minutes of arc • After finding the course angle from the triangle, convert it to a true course (0–360°) and check that the distance is reasonable for the change in latitude and longitude involved