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Open-water swim distance differs from the track recorded? (Todays swimrun 352m vs. approx 750m, unacceptable)

jmto
over 2 years ago

Hi,

Did my first open-water swim today with 955. Track looks nice and smooth, but the distance is something that makes me think.

Garmin Connect reports 3810m: https://connect.garmin.com/modern/activity/9055012148 

Opened the GPX in GPXSee as wanted to have a little bit closed look and it looked like it's 4k. Umm. Upload GPX to some online tool:


What are others seeing as open-water swim distance? Does it differ from the GPX track? 

Does anyone have any ideas/explanations to give?

Here is the exported GPX if someone wants to analyze it.
activity_9055012148.zip

EDIT: Apparently this was just a mild issue compared to todays one. Link to it: https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-955-series/298162/open-water-swim-distance-differs-from-the-track-recorded/1443414#1443414 

  • 0 over 2 years ago in reply to renton82

    Do you know this for a fact? I mean running has this auto calibration done outdoors that is later used for treadmill indoor running?

    And I'm quite sure most of us swims rather non-symmetrical?

  • 0 over 2 years ago in reply to cwikdahl

    I'm following this bug since Fenix 6/945, i have tried everything. I know for sure that there there isn't any calibration for OW swim.

  • 0 over 2 years ago in reply to renton82

    Ok. My 945 was about 10 sec/100 faster OW. Quite close to actual speed, maybe somewhat negative... But both are very constant at least. Was hoping for better OW accuracy with this watch thanks to the GPS chipset, but seems to be messed up by algorithms.. sad.

  • 0 over 2 years ago in reply to cwikdahl

    gpx shows good distances, but the distance shown by the watch is wrong. GPX will bridge signal outages a shows good data but when the signal fails, my swimming speed is 5min/km

  • 0 over 2 years ago in reply to VISOR13

    Same story since years...

  • 0 over 2 years ago in reply to renton82

    but, my forerunner 945 had better results. Forerunner 945 - mistake +10% until -20% , forerunner 955 mistake -30 until -50%

  • 0 over 2 years ago in reply to VISOR13

    My impression looking at teammates with older watches is also that they're way closer to reality than the FR955.

  • 0 over 2 years ago in reply to cwikdahl

    I have it on left wrist like the watch is. So I would say it's irrelevant. And idea of some kind of calibration is kind of absurd. The swimming speed is affected very much with many other factors than the wrist movement. Waves, currents, what are you wearing. Technic some could argue could be seen from the wrist movement but that also doesn't really tell the full picture of your form, etc. So I wouldn't even try to do some algorithm as it feels impossible.

    But Strava's correct distance, that's good tip, haven't though about it. Got my longest swim to look more proper now :D Yay, but of course it's still stupid on Garmin Connect.

  • 0 over 2 years ago in reply to 3064576

    I am sad that such a big mistake is in the top model of the watch and it has been going on for two months. No statement from garmin - that's a mistake!

  • 0 over 2 years ago in reply to renton82

    For me, it worked with latest firmwares with 945 so closely that I didn't even notice problems. So it's much worse with 955 for at least me. Normal OW swim is somewhat shorter but not so hugely terrible as the swimrun swims are. They are missing half the distance.

    So something has been "improved" with 955.