Facebook

Login

Support Sailonline

If you haven't already - join the SAILONLINE YACHT CLUB!

Please also consider making a donation - all amounts are greatly appreciated!

Board » General Discussion » Great circle-explanation please?

Posted by
Jepsom


Users avatar

Posts
30
Registered at
2008-01-28 20:27:15
2010-05-08 18:16:12 - Great circle-explanation please?
Hi

I´m not the best it-guru and I don´t understand all this about the Great Circle. So, can someone please explain way this happens. If you steer 270 degree west and then turn back, vs. rate, east 90 degrees. Why don´t you come back to the point from where you started?
Attachments
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2010-05-08 19:50:16 - Re: Great circle-explanation please?
The great circle is the shortest line between 2 points on the globe. (tip: play with a thread and 2 needles on an orange). This means that the course along a GC typically changes along the path. The courses in your examples are the courses to set at the turning points. Along the rest of the paths, the courses are different. Hence, your question is a little oddly put since you seem to refer to a loxodrome when you state that you steer a certain constant course. Tip 2: Zoom out a lot and play with the measuring tool and you will likely see what I mean.
...one of the guys behind the game...
Posted by
Jepsom


Users avatar

Posts
30
Registered at
2008-01-28 20:27:15
2010-05-08 21:09:14 - Re: Great circle-explanation please?
I hope that you do not think my question was a critical one...
And My Q was not "little oddly" :)))
I am a single Coca-Cola Salesman and no academics. So thats why I ask for things that I do not understand. I understand that it is the most direct route between two points on the globe, but became confused when I measured as in the example. Now you have explained and I have done my homework so that I will be more toxic than in the future;))
If you wonder about the difference between Coke Zero and Coke light, I will be the first to tell you ...;))


Thank! :)
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2010-05-09 01:19:39 - Re: Great circle-explanation please?
"Oddly little" the whole question is by being not able to open attachments in question.

It's fun though to put a face to Jepsom :)

Nice example of how the GC tool in SOL measures angles! Slightly unexpected, but no straight lines on this orange... Try it with CC.

We used to have a coke C2 that had 1/2 sugar but also artificial sweeteners... Maybe our resident guru can explain why they don't make it with 1/2 sugar but no compensatory chemicals for those of us who might like such a thing mixed with rum? ;)

--- Last Edited by 76Trombones at 2010-05-09 01:29:47 ---
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2010-05-09 06:24:38 - Re: Great circle-explanation please?
No problem Jepsom. These questions are very good in several ways. They makes us reflect on how the user interface works, how clear the manual is etc... Also, if you have such a question I bet there are 100 others wondering the same thing :-)

My only Coke-question is: Can I get the recipe please?

/Jakob
...one of the guys behind the game...
Posted by
Jepsom


Users avatar

Posts
30
Registered at
2008-01-28 20:27:15
2010-05-09 07:38:56 - Re: Great circle-explanation please?
Well...

First, 76: I will forward your question to the main office. While you wait for an answer, you may drink only Rome ... if you doubt the content ..;)

And Jakob: It´s all about money I think.. :)

Ps. It´s fun to put a face to 76trombone as well... I do understand you wife... ;) Ds.

/Jesper

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Aeolian Cruise 2025


This is the final race of the ARCH 2025 series and your last chance to improve your ranking. It promises to be an exciting 210nm slalom through the beautiful landscapes of the Aeolian Islands. Our Moody S38's will take off from Tropea and sail west between successive islands to reach the finish line in the Gulf of Palermo.
Fair Winds.
Race #1991
INFO from brainaid.de
Moody S38 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
ARQ4 - ARCH - SUPSOL - SYC
Race starts: Dec 15th 17:00 Registration Open!
▶ Flash
GO TO RACE

Chatham Island TIMED Chase 2025

The final TIMED race of 2025 takes us to the isolated and mysterious Chatham Islands archipelago 430 nm east of New Zealand’s South Island. There promises to be plenty of breeze from every point on the compass as we sail the Farr 38 around Chatham Island, Pitt Island, and The Forty Fours on this 124 nm course. This is a TIMEDrace so you may RE-REGISTER HEREto try again after finishing a run. You will have 13 days and 11 hours to test your skill and decision making after the race opens.
Race #1990
INFOby brainaid.de
Farr 38 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ4 - TRCH - SUPSOL - SYC
RACE CLOSE: Saturday,
27 December at 23:00 UTC
Race starts: Dec 14th 12:00 Registration Open!
▶ Flash
GO TO RACE

Christmas to Christmas Island 2025

Two waypoints, start and finish, and between them 5827 NM of two oceans. Not much time if we want to sit at the Christmas Eve table. You will need to maintain an average speed of over 10 knots, maybe quite possible with this Maxi Trimaran, but prepare your vessel well and choose the best of the many possible routes. Hands up everyone who knew there were TWO Christmas Islands?! OK, maybe you have sailed this Sailonline course before... but it's time to get ready for the 2025 challenge of racing between Christmas Island in the Pacific to Christmas Island in the Indian Ocean! It also marks the conclusion of our prestigious Ocean Race Championship 2025. Please have fun! Fair winds!
PRIZE: SMPF
Race #1967
INFO by brainaid.de
Maxi Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ4 - OCCH - SUPSOL - SYC
RACE CLOSE: Wednesday,
December 24 at 2300 UTC.
Race starts: Dec 01st 11:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member KaSToR
  2. Sailonline Yacht Club Member CriticalHippo
  3. Sailonline Yacht Club Member WRmirekd
  4. Sailonline Yacht Club Member rafa
  5. Sailonline Yacht Club Member vida
  6. Sailonline Yacht Club Member CollegeFund
  7. Sailonline Yacht Club Member bonknhoot
  8. Sailonline Yacht Club Member Panpyc
  9. Sailonline Yacht Club Member sassy63
  10. Sailonline Yacht Club Member BRENTGRAY

View full list

Series

Mobile Client

SYC members have the benefit of access to our mobile/lightweight web client!

The mobile client