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 » Distance To Finish - DTF

Posted by
zero


Users avatar

Posts
120
Registered at
2010-02-07 16:56:30
2014-02-21 05:49:02 - Distance To Finish - DTF
Could someone please explain how SOL calculates the Distance-To-Finish of each boat.

In many occasions a boat is clear ahead or behind and the DTF shows the opposite, until very close to the waypoint or finish line when the leaderboard starts to reflect reality.

It would be nice (and helpful) to see a sketch showing the logic behind the calculation.

I really appreciate, thank you.

Antonio
Posted by
outlaw


Users avatar

Posts
33
Registered at
2012-06-01 13:37:55
2014-02-21 12:51:34 - Re: Distance To Finish - DTF
Useful leaderboards can be found on the homepage.
You're welcome :p



For a more complete answer... but keep in mind that the above is 100% true... DTF is the great circle distance to the next waypoint, added up to the finish obviously. It's a bit more complicated, but that doesn't matter for your question, ask hmm if you must know.

The fundamental problem is we care about time to finish, not DTF.

As a thought experiment, imagine using the optimum angles tool and always sailing 'VMC to next waypoint'. This will by definition put you in the lead early on, the downside is you end up dead downwind of your goal quickly. At that point you have pretty much the worst VMC to next waypoint in the entire fleet!

A more useful scoring approach is to draw an advantage line, I tend to draw a line 90 degrees to my VMC target (that is VMC to bearing). Unfortunately you can't use this for race scoring, because different boats will have different targets, and targets change over time.

tldr the race leaderboard isn't very useful.
Posted by
kroppyer


Users avatar

Posts
347
Registered at
2010-02-05 15:25:55
2014-02-21 13:43:11 - Re: Distance To Finish - DTF
More information of hmm's blog:
here and here

And here's an image of how I believe it works. But outlaw is right, DTF is a poor measurement to predict ranking.

--- Last Edited by kroppyer at 2014-02-21 13:43:35 ---
Attachments
Posted by
zero


Users avatar

Posts
120
Registered at
2010-02-07 16:56:30
2014-02-22 00:09:47 - Re: Distance To Finish - DTF
Thanks Kroppyer.
That's very helpful.

I know that DTF is irrelevant until the very end, but still I want to understand the calculation behind it.
Just for fun :)

Antonio

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

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 Open!
▶ Flash
GO TO RACE

Lake Victoria TIMED Race 2026

This month’s TIMED race takes us inland to Lake Victoria in the heart of Africa. Starting at Rosebery Channel in Uganda sail the AC72v2 on a 196nm course around Bugala Island on the way to the finish line in Tanzania’s Speke Gulf. 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 #2018
INFOby brainaid.de
AC72v2 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ1 - TRCH - SYC
RACE CLOSE: Saturday,
28 March at 23:00 UTC
Race starts: Mar 15th 12:00 Registration Open!
▶ Flash
GO TO RACE

SSANZ Round North Island Race 2026 - Leg 4

The final challenge awaits in Leg Four of the Round North Island Series! From Napier, the fleet sets off on a 354 nautical mile run back to Auckland, completing the full circumnavigation where the journey began. Fatigue may be setting in, but this last leg could decide the overall standings. Sailing the fast and responsive Sun Fast 3600, our skippers will need sharp tactics and steady focus to finish the series strong and claim victory!

The start time for this race may change at short notice to align with the real race. The confirmed start date and time will be announced via an in-race “L” flag message — Please monitor race communications closely.
Race #2014
INFO by brainaid.de
Sun Fast 3600 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: RNI - SUPBUD - SYC
RACE CLOSE: Friday,
March 20 at 2300 UTC.
Race starts: Mar 12th 22:00 Registration Closed
▶ Flash
GO TO RACE

Iceland to the Falklands 2026

Welcome to an all-new route, the first of three Round the 'Old World' of Europe, Africa, Australia and Asia. To give each leg of the ROW a bit of length we'll try to hug the coasts as little as possible, so starting in Iceland our first leg of the series, which will also be the final leg of our Quarter 1 Ocean Championships takes us 7200nm to the Falklands, the full length of the Atlantic end to end. To make sure we'll get it done within the month we'll be sailing our Maxi Trimaran.
Race #2010
INFO by brainaid.de
Maxi Trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ1 - ROW - OCCH - SYC
RACE CLOSE: Tuesday,
March 24 at 2300 UTC.
Race starts: Mar 02nd 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 WRmirekd
  3. Sailonline Yacht Club Member rafa
  4. Sailonline Yacht Club Member rumskib
  5. Sailonline Yacht Club Member Sax747
  6. Sailonline Yacht Club Member CriticalHippo
  7. Sailonline Yacht Club Member vida
  8. Sailonline Yacht Club Member CollegeFund
  9. Sailonline Yacht Club Member Panpyc
  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