After I had looked into the Titanic’s navigation for a while I came to hoping someone in Britain would look up the surviving Olympic records because they would be an ideal example of the methods and personal styles used in conducting the Titanic’s trip. Well thank you Mark and Sam, now I have quite a slice of this. I of course immediately put all those 200th voyage locations you posted into one of my spread sheets to get the distances, speeds, possible times changes, etc. I don’t know if you have further info for future use or not but this alone was quite interesting.
The observations that came out are:
-as you say Sam, they passed about 10 miles to the south of Bishop Rock. Once I plotted the course from exactly Bishop and saw the variance from the ideal great circle for each turn I went back and changed the GC start to a rounded 49d42’N 6d27’W and suddenly they stayed within 2.4 miles of the GC for every turn. I understand there are lots of hazards for the first few miles south of Bishop so this all seems to make sense, they want to turn North West here but not that closely.
-the speed was fairly constant, very close to 22 knots the whole way.
-I take it that the 60d31’W figure for Monday noon is a typo of some sort , they couldn’t get there from turning The Corner at 4:40pm without making 23.6 knots.
-if the time changes are figured from noon to noon using a projected 22 knot speed then they come within 1 minute of the noon sun times achieved each day. I got changes of 35-55-54-48-47-61 minutes for Wednesday to Monday nights. I assume Southampton departure was about 4 pm.
-the obvious ways for choosing turn points along a great circle are by time interval, by distance in miles, by distance in degrees long from the previous noon, ditto from a round figured long, by ideal sight time near sunrise or sunset and by sight time to suit some ideal stars -well, okay if they are not near sunrise/sunset then what are you using as a visible horizon? Well none of these patterns fit, not even close. I checked the sunrise/sunset times for what appeared to be the location of each turn and I loaded the locations and GMT into HomePlanet (free, no hooks
http://www.fourmilab.ch) to see if the sky those nights showed any pattern of looking at major navigation stars or looking away from the moon, no luck.
My best guess was that they planned the trips from noon to noon as I feel they had always done and then just added in the subdivisions to appease a 1930’s economy drive. Each day appears to have been subdivided to 3 intervals of sometimes 5 hours and sometimes 2.5-3 degrees and then the last interval was just sighted to finish out the day to noon.
As far as the economies achieved, Capt’n Collins hit it, I got savings of 1.84 miles in 1643.34. The legs from Bishop to Thursday noon and from Sunday noon to The Corner are of course the same as on a one turn per day scheme so it is only Thursday noon to Sunday noon where a saving can be made. I figure that they could either shave 4.9 minutes off the trip for a direct reduction in cost or they could reduce speed by 0.024 knots and arrive on schedule for a “speed squared” reduction in cost. Either way the savings are not even a pittance. I figured their fuel bill in 2005-2007 prices so we could appreciate how it felt to them and while saving $275 or $550 per day of GC sailing would seem to justify taking an officer’s time away from other duties, the benefit of trimming $20-40k from a $36 million per year fuel bill wasn’t going to solve anything. I frankly felt it wasn’t worth the jeopardizing of navigation accuracy.
Anyway much thanks for the data, Bill
