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Board » General Discussion » Distance To Finish - DTF

Posted by
zero


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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


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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


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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 ---
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Posted by
zero


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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

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