David G. Brown
RIP
June 18th 1911. Olympic’s Noon position was 17+ nautical miles - North-west’ly - OFF the GC track.When following a great circle path, a ship must make several heading changes to stay close to the track. From detailed data that we studied from several Olympic voyages, it appears that course segments (in true degrees) would be laid down at Local Apparent Noon (LAN) each day. However, it also seems that very small course adjustments took place as often as every six hours. Whenever possible, being on a great circle path is desired, since it minimizes the overall length of a passage.
Yes! Your observation (highlighted), and explanation given, is foreign to the practice of ocean navigation, especially in 1911 prior to satellite navigation.Is there some point you wish to make Capt.?
Foreign to the practice of ocean navigation prior to satellite navigation? Hmmm! Well let's look at what was recorded for Olympic's 200th voyage from Southampton to NY via Cherbourg in 1931 while traveling the great circle part of her route from Bishop Rock to a corner point at 43N, 50W; then to Nantucket Light Vessel; then to Ambrose Light Vessel. Course headings recorded were in degrees true and time recorded were ATS. This data came from a course book document that Mark Chirnside had shared with me and is presented here with his kind permission.Your observation (highlighted), and explanation given, is foreign to the practice of ocean navigation, especially in 1911 prior to satellite navigation.
The difference between Olympic's 200th voyage actual track distance, with 14 course alterations, and Rhumb (line) tracks from Bishop’s Rock 49° 42'N, 6° 27'W to Corner 43°N, 50°W, with course alterations at noon each day = 1.75 nm @ 22 knots = 5 minutes.Olympic's 200th voyage from Southampton to NY via Cherbourg in 1931 while traveling the great circle part of her route from Bishop Rock to a corner point at 43N, 50W;
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