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13 Comments

  1. Ivan
    May 24, 2019 @ 09:59

    Very good article Patrick!

    Reply

  2. Rozgonyi Balázs
    May 29, 2019 @ 01:33

    if i may ask, why does True Wind calibration goes out of, well, calibration?

    Reply

    • Johan Barne
      May 29, 2019 @ 23:11

      Dear Rozgonyi!

      The wind calibration is needed due to that the wind is affected by the top of the rig (and some other minor items). That effect is different in different wind speeds and different wind angles. Therefore different wind calibration values is needed for every wind speed and angle.

      However, wind speed is only measured at one height = the mast height. Depending on the weather and wind profile, the wind at other heights can variate for at a certain wind speed measured at mast height. The wind at other heights affect the flow at the top as well.

      Subsequently, the wind calibration needs to be adjusted as conditions changes.

      Reply

  3. Torben Falholt
    Jul 9, 2019 @ 13:16

    Very interesting article. I am a little confused on how to Heel correction function works. The numbers in the table show’s what ? 0 Degree at 2,5 kn show a correction factor of 0.68 in the above table. What does this factor represent.

    Also if I wanted to calibrate my boat – how would I be able to measure my speed with a heel of 20% degree ??

    Reply

    • Torben Falholt
      Jul 9, 2019 @ 19:14

      I resign from this question. After upgrading the CPU to the latest software level – the calibration issue has changed – and this question is not on my agenda.

      Reply

  4. David Eastwood
    Jul 19, 2019 @ 09:07

    I find it’s helpful to log AWA/MWA and AWS/MWS – comparing these values post-fact is useful as it tells you whether your wind calibrations are about right. MWS/MWA are sort of checksums for the calibrations.

    In H5000, AWA/AWS values are back-calculated from TWA/TWS whereas MWA/MWS are the raw values from the sensors. In a perfectly calibrated world, MWA=AWA and MWS=AWS. However, as the output variables are damped and the sensor data isn’t, you need to compare the values by logging them and loading to a spreadsheet over a time period and calculate averages.

    On the water, you can eyeball AWA/AWS vs MWA/MWS in StripChart or the B&G Web interface to get a feel for any errors but it’s a bit imprecise.

    To log MWA/MWS you need to be using the Websocket interface to Expedition, they aren’t available over HLink for some bizarre reason.

    Reply

    • Peter Gustafsson
      Jul 19, 2019 @ 11:41

      Great tip David!

      Reply

    • Andy Robertson
      May 3, 2022 @ 01:09

      David – upwind i have an average difference of .1 where MWS is lower than AWS – yet the TWS average is well lower. I know that it should be – but by feel the TWS is too low. This is also backed by the TWS was 15knts going into the top mark, 18knts on the reach and 21knts going into the run. The wind built a bit but not that much- so by intuition the TWS upwind is reading too low. But are you saying that if the MWS=AWS then a TWS adjustment is not required? or would i still look to add say +2 or 3 to the TWS upwind?

      Reply

  5. David Eastwood
    Jul 22, 2019 @ 22:55

    👍

    Reply

  6. Dave Nauber
    Jun 19, 2022 @ 17:45

    Maybe not the right place for this question, but when pinging the starting line, do the ends need to be pinged from a certain direction (i.e. mark at the bow, bow head to wind)? I would think mark at the bow from any direction should work if the offset from GPS to bow is entered correctly.

    Reply

    • Peter Gustafsson
      Jun 20, 2022 @ 07:56

      I think this is taken care of by the software. That said, we try to be consistent with the “standard way” (i.e. mark at the bow, bow head to wind).

      Also helps with traffic since everyone is pinging in a similar pattern 😃

      Reply

  7. Eric Petersen
    Jun 26, 2022 @ 03:38

    Can someone explain what the upwind angle and down angle numbers are for?

    Upwind angle 165?

    Down Angle 135, 140, etc.?

    Reply

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