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dorox last won the day on December 29 2020

dorox had the most liked content!

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About dorox

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    Sailing data analysis.

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  1. dorox

    INEOS Team GB

    I have to say, these PR videos might not help them sail faster, but INEOS do get some credits for outreach.
  2. dorox

    Boats and foils comparison

    Scraped from This, or from my website.
  3. dorox

    Boats and foils comparison

    I've updated my web app with new races data:
  4. dorox

    Prada Cup

    I think VMG is calculated using TWA from boat wind instruments. Distance to leader seems to be derived from next mark wind instruments (the buoys are fitted with those). So when there is a wind shift at the leg end, there is such divergence. Also, wind-VMG at the top of the leg isn't perfect because boat is sailing to the mark, not to the wind. Lots of nuances, hard to get it right and simple.
  5. dorox

    Boats and foils comparison

    My job here is done: AC web team added plots.
  6. dorox

    Boats and foils comparison

    So I'll try do add that later. And there is yaw angle to be derived from heading and GPS, too. There is also wind and course data that I want to plot on the map as well. It is on GitHub in a private repository. I didn't want to make it public after reading T&Cs on the AC website, though. (giggling nervously) We have to be thankful for race committee for publishing so much data: F1 is much more secretive, for example.
  7. dorox

    Boats and foils comparison

    On my website I have VMG to the wind direction. The problem is that because wind changes direction, the integrated w-VMG and c-VMG would be different. Even more, integrated w-VMG would be different boat to boat. If you are just looking at race progress, the c-VMG is the way to go. If you want to see distance lost/gained during maneuvers, the w-VMG is the better one. But I might be wrong though. If you click on the slider handle, then you can move it right and left one step at a time with keyboard arrows
  8. dorox

    Boats and foils comparison

    CMG is quite simple to add, just one question: should it be derived from wind VMG, or course VMG, or simply the distance sailed from GPS? Re colour gradients: this is doable, but in a form of scatter (colour-coded dots along the boat track)
  9. dorox

    Boats and foils comparison

    Update: now all races are available at Thanks to @MaxHugen for boat images. If you zoom in, you should see schematic AC75s drawn to scale.
  10. dorox

    Boats and foils comparison

    the data is in UTM format for zone 60S. If I understand correctly, these are x, y coordinates in meters relative to a specific point. Mark data is there too, but is arguably harder to pull out. There is also wind data for buoys and committee boat and race boundaries. You can actually get the leeway angle from the available GPS velocity vector and heading. Alternatively, you can see it for yourself here The boat heading data is used to rotate the boat icon independently of GPS. So if you zoom in to see the boat icons, you'll notice their heading is not always aligned with GPS track. This is especially pronounced on downwind legs.
  11. dorox

    Boats and foils comparison

    I made another web app with boat tracks and data side-by-side. It is better to use it on a PC, because map zoom doesn't seem to work on mobile. So far it has only race 8 from Prada cup. You can scroll the slider at the bottom to change the time and see the race progress. It seems like LR got really unlucky with wind shifts at the last upwind. The boats are shown roughly to scale, but I didn't have a good image for AC75 from above. If someone wants to draw it, it would be really cool. It has to be .png with transparent background.
  12. dorox

    Prada Cup

    TWS data for GBR is consistently higher by 1-2 kn. This is comparing to other boats' TWS data, as well as stationary wind instruments on the course (buoys, committee boat, etc.). Hence it is wrong to compare TWS between boat to boat. One can't say GBR was sailing in consistently stronger breeze. VMG/TWS data becomes skewed as a result of TWS data: i.e. GBR would be showing smaller VMG/TWS, because their TWS is higher. The best measure for a boat to boat comparison would be simple VMG.
  13. dorox

    Emirates Team New Zealand.

    I hope they'll make an AC simulator game together.
  14. dorox

    Boats and foils comparison

    LR data. @X35 GER50, note the wind strength was different between two weeks, so vmg/tws might be better.
  15. Hi, is it possible to get access to the raw data of AC36?

    Would like to run some statics

    I would really appreciate that