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Fenix 6s Open Water Swimming under reporting distance & pace

Former Member
Former Member over 5 years ago

I've upgraded to the Fenix 6s sapphire and the distance (and thus pace) is being under calculated on open water swimming. At first I thought I was just having a slow day or the current was stronger than usual but over multiple attempts I am getting the same result.

I have swam in the same bay for years and from my previous watch, triathlon times  and pool pace I know I average between 1:50 and 2:00 per 100m yet on the Garmin 6s it is showing more like 2:30m per 100m. 

I wore my friends Fenix 5 on one wrist with the 6 on the other and over a 600m swim the 6s reports 500m. Likewise over an Olympic triathlon distance swim (1800m) the 6s shows closer to 1500m. 

I have switched between glonass / galileo and changed GPS to every second to no avail. It seems to be more an error in the distance calculation rather than the GPS tracking as the route shows as accurate when looking at the  map post swim. Worth noting distance and pace is accurate for running and cycling. 

Has anyone else experienced this?  

  • 0 over 4 years ago in reply to renton82
    Dr Phil said:
    But what is the accurately measured distance?
  • 0 over 4 years ago in reply to renton82

    Clearly I'm in the wrong. All other devices must be correct and you have a problem with your particular watch. In the light of that obvious result I would suggest you contact Garmin and work with them to resolve a problem that is clearly plaguing your watch.

  • 0 over 4 years ago in reply to Dr Phil

    Last year I replaced 2 Fenix 6x pro solar for screen problems and now i have a Delta Solar and all of them exhibit this problem, so i really think it's a software problem or maybe open water swimming doesn't work at my latitude... who knows....

  • 0 over 4 years ago in reply to renton82

    I guess you will loose a couple of seconds on the turns. Try swimming in the pool without touching the wall. That will probably not account for all the difference. I think that the GPS error (a couple of meters) is more noticable when swimming short laps. On longer stretches i believe that the errors evens out more.

    BTW, if you look at the GritX track, that measured distance _must_ be much longer than in the real world.

  • 0 over 4 years ago in reply to broyson

    I noticed that as soon as i start to swim, lap distance remains at 0m until 5/10 seconds, than starts to count from 1 meter and that's clearly wrong since in 10 sec i surely swim about 10 meters... strange thing is that start and end point is correct on the map, it seems it calculate the distance in wrong way.

  • 0 over 4 years ago in reply to renton82

    Are you swimming intervals and resting at the turns? Then you need to make sure that the watch stays above the water long enough to get a position fix at lap start.

  • 0 over 4 years ago in reply to broyson

    Not always... sometimes i turn without rest and sometimes i rest without turn, however, when i'm resting i always keep the watch above water for a GPS fix.

  • 0 over 4 years ago

    I've done a quick test today: i walk for about 70m using open water activity and come back on the same path using walking activity. The video I made speaks alone: in open water activity, watch starts to count distance too late resulting in about half of registered distance. If you swim making repeated, this error become much more pronounced! I also notice during another test that if i stop from walking without stopping activity, watch continue to add meters to distance and after about 20 seconds it reaches almost corrected distance. 

    However, there is for sure something wrong with open water activity...

    Here you are the video:

    https://youtu.be/M88WksWOn1w

  • Former Member
    0 Former Member over 4 years ago in reply to renton82

    I noticed you started your activity and resumed it literally within a second or two of getting a green GPS bar.  Do you get the same results if you wait 30 seconds to a minute after the green bar appears as many have suggested is the best practice?  This may explain why some get bad data and others don't?

    I just found this on Garmin's website:

    When a device initially displays that GPS is ready, it means that the device has picked up the minimum amount of satellites needed to get your location. Waiting a few moments after your device finds a signal will allow additional time to communicate with satellites before you start moving for your activity. This practice allows for your device to communicate to additional satellites, creating a stronger bond and helping to reduce degradation of GPS signal.