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 versus loxodrome

Posted by
Nea


Users avatar

Posts
1
Registered at
2008-01-17 23:04:43
2009-01-18 15:52:02 - Great circle versus loxodrome
If the line from start to goal is the loxodrome, does sailonline calculate distances taking great circle into account.
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2009-01-21 14:30:27 - Re: Great circle versus loxodrome
I don´t really understand what you are asking for but the boats sail in loxodromes if constant cc is set. So does the course tool and "ruler".
...one of the guys behind the game...
Posted by
Velum SUI


Users avatar

Posts
2
Registered at
2007-11-07 09:37:58
2009-01-28 15:57:06 - Re: Great circle versus loxodrome
hmm, may I enhance the question?

I read in the manual:
"In Sailonline you can choose to navigate using great circles."

How?
I only know navigation using CC (loxodrome) and TWA, but not great circle navigation.

Can you explain?
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2009-01-28 17:06:23 - Re: Great circle versus loxodrome
Well... in the old client you could chose. In the web-based client you cannot.. yet...
...one of the guys behind the game...
Posted by
captjack1942


Users avatar

Posts
239
Registered at
2008-01-18 03:24:03
2009-01-28 23:34:12 - Re: Great circle versus loxodrome
In the meantime there are a few web based calculators for great circle, I like this one (cause it is easy to enter lat/long in same format as sol chart): http://www.waypoint.org/gps1-calc.html
Posted by
Velum SUI


Users avatar

Posts
2
Registered at
2007-11-07 09:37:58
2009-02-11 07:33:41 - Re: Great circle versus loxodrome
Last night I anchored at the coast,
because I had scheduled my tacks too early for the decreasing winds.

I am a newbie in this, I guess following idea was discussed already before, but I couldn't find anything on it, so:

A steering option like "steering towards a coordinate" could be useful for great circle navigation as well as to launch new commands by reaching a position (not by time). This would allow me to program a much more reasonable and reliable behaviour during my absences.

Sorry for this silly wish, but I am one of the old fashioned human beings that still require some hours sleep per day, have fixed working hours, but still enjoy this game very much.


--- Last Edited by Velum SUI at 2009-02-11 13:09:37 ---
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2009-02-11 12:55:52 - Re: Great circle versus loxodrome
Hi! Your request is understandable, not new and logic. Different steering alternatives are discussed and on our list. Thanks for communicating :-)
...one of the guys behind the game...
Posted by
Zembu


Users avatar

Posts
41
Registered at
2008-12-15 20:58:27
2009-02-14 22:59:18 - Re: Great circle versus loxodrome
This is not a reply but a query related to this topic.
I think there is an error in the way the "ruler" works now. The map is Mercator Projection I believe, which is created by projecting the earth's surface onto a surrounding cylinder as if illuminated from within using a line light source from North to South poles. Thus the latitudes are horizontal, and towards the poles the area is stretched latitudinally. Using such a projection for Great Circle lines, a theoretical Great Circle line drawn on the earth's surface from Qingdao to Cape Horn and projected on your Mercator projected map would not go further south than necessary to round the horn. But your lines go far further south, and even traverse across Australia and other land. I think your algorithm for the Great Circle lines assumes some sort of projection as if from a point source at the centre of the earth instead of from a line source.
Posted by
Zembu


Users avatar

Posts
41
Registered at
2008-12-15 20:58:27
2009-02-15 14:00:23 - Re: Great circle versus loxodrome
Further to my previous (2009-02-14 22:59:18) I see that I am wrong and you are right - as you knew all along I guess - you were just too nice to say so. Not having a globe of the world I experimented with a baseball, a flowerpot, a pencil and a pair of dividers, and I see that by my approximate method the line from Qingdao to Cape Horn could go as far as 70 degrees South. So your 75 degrees is I guess correct. Sorry for doubting you all! :-)

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

ORCV Melbourne to Hobart 2024


Welcome to the legendary "Westcoaster," a race that has tested sailors for over 50 years. Spanning 435 nautical miles, this iconic journey takes racers from Melbourne, across the formidable Bass Strait, and around Tasmania's rugged west coast to the finish line in Hobart. Organized by the Ocean Racing Club of Victoria, the Westcoaster is renowned for its challenging conditions and adventurous spirit. This year, our SOLers will tackle the course in the swift and capable First 47.7, a yacht launched by Beneteau in 2000, built for speed and endurance in long ocean races. Get ready for an exhilarating ride in one of Australia’s most celebrated yacht races!
Race #1841
INFO by brainaid.de
First 47.7 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Dec 26th 23:00 Registration will open soon
▶ Flash
GO TO RACE

Refeno Rally 2024


Although since 1986 this 300nm course from Recife, Brazil, to Fernando Noronha Island has been run many times IRL, we have only used this route twice in SOL. This time it will be the route of the last race in the ARCH 2024 classification.
Although the winner of the general classification can already be determined, the fight for the next places on the podium should be fierce. There are several contenders and Dofour34 have them at their disposal. Since we are starting in Vida_Maldita's home waters, he will give us a 30-minute handicap. Or maybe we should give it to him? 😊
Race #1865
INFO from brainaid.de
Dufour 34 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
ARQ4 - ARCH - SUPSOL - SYC
Race starts: Dec 23rd 17:00 Registration Open!
▶ Flash
GO TO RACE

Tristan da Cunha TIMED Race 2024

Originally designed by NZL_Scotsman, we head for the remote outpost of Tristan da Cunha where gales and storms may come and go but the sea is everlasting. This 64nm TIMED race has been raced on several occasions before, and this time we will be doing it in Rustler 36s.
RE-REGISTER HERE to race again after finishing a run
Race #1875
INFO by brainaid.de
Rustler 36 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ4 - TRCH - SUPSOL - SYC
REGISTRATION CLOSE: Saturday, 28 December at 22:00 UTC
RACE CLOSE: Saturday, 28 December at 23:00 UTC
Race starts: Dec 15th 12:00 Registration Open!
▶ Flash
GO TO RACE

The Beagle in the Azores 2024


And west the Beagle went one final time to round the Cape of Good Hope on May 31 1836. Ashore, Darwin met up with the Astronomer Royal, Herschel, who just happened to be in South Africa at the same time mapping the southern skies. After sounding out his many ideas on evolution and extinction with Herschel, the Beagle now sailed north, stopping briefly in St Helena, Ascension and Brazil, and the Cape Verdes again, to reach the Azores on September 19, 1836. Fitzroy and Darwin at this stage were in a hurry to get back to Britain, but online in 2024 we will stay a little longer to explore this final remote archipelago in our virtual Tall Ship Class B Beagle, 630nm round and about the islands, minding as always in these waters not to bump into any large cetaceans!
Race #1758
INFOby brainaid.de
Tall Ship Class B PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SVF - SYC
RACE CLOSE: Friday,
December 27 at 2300 UTC.
Race starts: Dec 14th 13:00 Registration Closed
▶ Flash
GO TO RACE

Christmas(W) to Christmas(E) Island 2024

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, so prepare your 90ft 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 2024 challenge of a reversed race, starting in the Indian Ocean, racing to the Christmas Island in the Pacific! It also marks the conclusion of our prestigious Ocean Race Championship 2024. Please have fun! Fair winds!
PRIZE: SMPF
Race #1868
INFO by brainaid.de
90ft Monohull PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ4 - OCCH - SUPSOL - SYC
Race starts: Dec 02nd 11:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member FreyjaUSA
  3. Sailonline Yacht Club Member Vida_Maldita
  4. Sailonline Yacht Club Member CriticalHippo
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member Kipper1258
  7. Sailonline Yacht Club Member Satori
  8. Sailonline Yacht Club Member Sax747
  9. Sailonline Yacht Club Member BRENTGRAY
  10. Sailonline Yacht Club Member CollegeFund

View full list

Series

Mobile Client

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

The mobile client