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Board » Technical Support » Rhumb lines versus Great Circle routes

Posted by
Chappo


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2009-04-17 12:00:35
2009-11-12 00:46:40 - Rhumb lines versus Great Circle routes
This may be muddled thinking but when you use the divider to check distances, it draws a great circle route. In the case of the Transatlantic race, the distance matches the declared sailing distance. So if you are sailing the rhumb line as shown on the SOL course, aren't you actually sailing a great circle route. I am curious that if you sail the great circle route drawn by the dividers between Boston and Plymouth, aren't you effectively sailing the rhumb line as shown on the SOL course.
Posted by
jakob


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2007-09-04 10:05:30
2009-11-12 08:00:56 - Re: Rhumb lines versus Great Circle routes
Hi. The course is shown as a rhumb line (not great circle) and the divider uses the great circle. So yes, if you sail with a constant compass course along the rhumb line you will sail a longer distance. Did I answer your q?
...one of the guys behind the game...
Posted by
Chappo


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2009-11-12 10:28:36 - Re: Rhumb lines versus Great Circle routes
Thanks Jakob. So is it correct that the great circle route is the shortest distance but it requires a changing compass heading the whole time? A rhumb line is a constant heading but is a longer route especially as you approach the poles. Is it correct to say that in practice it is partly academic because a routing programs like SP (I am a subscriber, great product)concentrates on putting you into the best pressure and polar lines for the longest times and this more than compensates for extra distance sailed following rhumb lines?
Posted by
Incognito


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2008-12-06 13:43:52
2009-11-12 10:38:36 - Re: Rhumb lines versus Great Circle routes
All correct.
Posted by
Chappo


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2009-04-17 12:00:35
2009-11-12 10:47:59 - Re: Rhumb lines versus Great Circle routes
Thanks Incognito. So in a perfect world SP picks the great circle route between Boston and Plymouth and doesn't change that prediction for 5 days!!!
Posted by
Incognito


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2009-11-12 10:50:06 - Re: Rhumb lines versus Great Circle routes
Yes, assuming that in your perfect world there is no land either.
;-)

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