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 » Technical Support » Is the DTG calculation correct

Posted by
mwagg56


Users avatar

Posts
2
Registered at
2009-03-23 23:12:20
2009-05-22 05:03:29 - Is the DTG calculation correct
Is it just me but does the DTG calculation seem incorrect. Seems to be too much north of the rum line!
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2009-05-22 05:46:31 - Re: Is the DTG calculation correct
DTG is calculated along a great circle (shortest way) and not the along rhumb-line (constant course). ok?
...one of the guys behind the game...
Posted by
mwagg56


Users avatar

Posts
2
Registered at
2009-03-23 23:12:20
2009-05-22 05:59:59 - Re: Is the DTG calculation correct
I understand. However, checking with the great circle tool suggests that the DTG for boats above the rum line is incorrect. eg STU131270 is reading around 917nm to go but the great circle tool suggests the true distance is about 100 nm less.
Posted by
jakob


Users avatar

Posts
364
Registered at
2007-09-04 10:05:30
2009-05-22 06:42:53 - Re: Is the DTG calculation correct
DTG-calcs over long ranges when rounding of waypoints are involved are tricky. Just be cool and things will sort out as you get closer, I promise.
...one of the guys behind the game...
Posted by
Incognito


Users avatar

Posts
183
Registered at
2008-12-06 13:43:52
2009-05-22 07:34:48 - Re: Is the DTG calculation correct
Hi SOLer's,

I have just opened a similar thread. Sorry to repost here.

Jakob, I do not want to be mean, but you seem to be in denial. ;-)

According to SOL, at 7:00 UCT, I was ranked 86th with more than 674 NM to go.

In brainaid's ranking however (http://sol.brainaid.de/pub/ranking-145.html), I was ranked 14th with 637 NM to go.

Quite a difference! And when I use the pliers or the pointer to calculate the DTG, I come to a figure similar to brainaid's.

We had similar issues in led 5. Personnally, I remain convinced that there is an error in the formula used to calculate the DTG in SOL's ranking. It would be nice to fix that sometime.

Regards,

Francois on Incognito

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Gladstone Ports Corporation Brisbane to Gladstone Yacht Race 2026


Sailonline is thrilled to partner with the Queensland Cruising Yacht Club for the 2026 Gladstone Ports Corporation Brisbane to Gladstone Yacht Race! This 308 nautical mile offshore challenge follows Australia’s stunning east coast from Brisbane to Gladstone. Racing the fast and tactical Farr 40, sailors will need precision, strategy, and focus as shifting conditions test every decision from start to finish!
Race #2027
INFO by brainaid.de
Farr 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SUPBUD - SYC
Race starts: Apr 03rd 01:00 Registration Open!
▶ Flash
GO TO RACE

Rapallo to Nador 2026


Welcome to Liguria’s Rapallo, there where Zarathustra spoke - at length - to Nietzsche, for our first race of nine to celebrate all things Mediterranean - fickle winds, history and olive oil. A number of our races in this new Magical Mediterranean series will be partnership with famous real-life races, but this first race is pure fiction - 780nm in refurbed IMOCA 60s, past or through the Balearic Isles and on into the Alboran Sea, to a finish off Nador on the Maroc Mediterranean coast.
Race #1975
INFOby brainaid.de
IMOCA 60v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SYC
Race starts: Mar 30th 15:00 Registration Open!
▶ Flash
GO TO RACE

Red Eye - Melville Island PYOC 2026

Melville Island is the largest of the Tivi group opposite the port of Darwin in the Timor Sea. Tropically forested and thinly populated, not a lot goes on there, but let’s race around it anyway, lar- or starboard round, it’s a little more than 120nm, so, no matter where you are navigating from on the planet, you will be hard-pressed to complete the course aboard your J-80 in daylight hours!
Race #2003
INFOby brainaid.de
J-80 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RED - SYC
RACE CLOSE: Tuesday,
March 31 at 2300 UTC.
Race starts: Mar 24th 12:00 Registration Closed
▶ Flash
GO TO RACE

Cross the Convergence 2026 - Guam to Ouvéa


The third race of our series of ocean voyages across the World’s convergence zones takes us southeastward now down the Pacific, from Guam’s Apra Harbour at 13.5 degrees North, back across the Equator to the glorious New Caledonian resort island of Ouvéa, on the edge of the Tropic of Capricorn at 20.5 degrees South. It’s 2400nm, and there’s more than a few other islands in the way, so mind where you go in your Ocean 50s. Race #1981
INFOby brainaid.de
Ocean 50PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: CCZ - SYC
Race starts: Mar 20th 18:00 Registration Closed
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member KaSToR
  2. Sailonline Yacht Club Member WRmirekd
  3. Sailonline Yacht Club Member rafa
  4. Sailonline Yacht Club Member rumskib
  5. Sailonline Yacht Club Member Panpyc
  6. Sailonline Yacht Club Member CollegeFund
  7. Sailonline Yacht Club Member Sax747
  8. Sailonline Yacht Club Member CriticalHippo
  9. Sailonline Yacht Club Member vida
  10. Sailonline Yacht Club Member sassy63

View full list

Series

Mobile Client

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

The mobile client