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  •  » Drift and Set Not Calculating in 12.7.16 (Navionics)

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    5/30/2026 5:45 pm  #1

    jbranson
    Admiral

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    Registered: 5/07/2022
    Posts: 16

    Drift and Set Not Calculating in 12.7.16 (Navionics)

    I can't work out why drift and set is not being calculated after selecting "Calculate Set and Drift" in the System options in All Settings.  I believe I have all the NMEA sentences needed to do the calculation:

    $--VHW Water speed and heading
    $--HDT Heading true
    $--HDG Heading magnetic + deviation/variation
    $--RMC GPS position, COG, SOG
    $--VTG COG and SOG

    I also don't see TWA, TWS or TWD values unless I select to calculate them.  I know I'm receiving the NMEA sentences $--MWV and $--MWD

    What am I missing?
    I'm running v12.7.15 for Navionics.

     

    Last edited by jbranson (5/30/2026 5:51 pm)

     

    6/22/2026 5:03 pm  #2

    jbranson
    Admiral

    Offline

    Registered: 5/07/2022
    Posts: 16

    Re: Drift and Set Not Calculating in 12.7.16 (Navionics)

    I'm now seeing weird numbers for TWA and TWD.  TWD is out by 10-15 degrees compared to the boat's MFD.  The boat electronics are a relatively new Raymarine system.  TWS is out by about 15%.  I've unchecked the options to have Expedition calculate TWS and TWD.  Is there anything else I should be looking at?
     

       •Thread Starter
     

    6/22/2026 7:40 pm  #3

    Nick
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    Registered: 9/16/2015
    Posts: 3,435

    Re: Drift and Set Not Calculating in 12.7.16 (Navionics)

    Are you getting TWS & TWD from Raymarine? I thought they didn't send those.

    Check the AWA, AWS, HDG and BSP values are the same in Exp as you are seeing in Raymarine world. It may be that you have more than one source.

     

    6/22/2026 8:15 pm  #4

    jbranson
    Admiral

    Offline

    Registered: 5/07/2022
    Posts: 16

    Re: Drift and Set Not Calculating in 12.7.16 (Navionics)

    I'm getting the TWS and TWD from Raymarine but it's like the TWD is having local variation added to it.  If I set the mode to True (i.e. uncheck Magnetic), I get the right number.

    AWA, AWS, HDG and BSP are the same in Expedition and Raymarine.

       •Thread Starter
     

    6/22/2026 8:32 pm  #5

    Nick
    Moderator

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    Registered: 9/16/2015
    Posts: 3,435

    Re: Drift and Set Not Calculating in 12.7.16 (Navionics)

    You could post or email a sample of the raw data into Exp (the text file, not an image) along with what you thing the twd should be (magnetic and true).

     

    6/23/2026 1:14 am  #6

    jbranson
    Admiral

    Offline

    Registered: 5/07/2022
    Posts: 16

    Re: Drift and Set Not Calculating in 12.7.16 (Navionics)

    Hi Nick, I just tried to upload to this forum but it won't accept .txt files.  Where should I email them?

       •Thread Starter
     

     

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