OW swim and GPS accuracy

The Fenix  7xs is accompanying me for almost 2 months, I do running, swimming, and biking with it. Pool swimming was without problems so far. I started OW swimming 2 days ago, and it seem to work somehow. The watch recorded a track I swam, but distance was almost 200 m too low, as I found out by exporting the track as a gpx file and reloaded back to Garmin connect. It seem, as if the watch does record gps points correct but somehow mix up numbers in the header: (record 1305m, correct would be 1530 m). Today I swam another round with a comparable path, and this time the track was completely mixed, giving sort of a fantasy path. Swimming distance was slightly longer, close to 2000m.

With respect to GPS track recording and distance calculating: Running as well as biking show similar ‚low-distance-recording‘ of about 2%, which apparently has nothing to do with hardware recording in the watch. This ‚error’ was observed also for previous models. Why, Garmin, can‘t you get the most important thing not correct, which just seem to be a software issue?

  • Oh and situation is even worse than I thought :( Todays swimrun wasn't very good. Got 352m and real distance is over two times longer.


    I would speculate they are using some stupid algorithm for the distance and not the GPS track distance and this algorithm goes bad especially if one is swimming with paddles and a wetsuit.

  • Even worse, when contacting Garmin, here's what was replied:

    Guten Nachmittag, vielen Dank für Ihre Nachricht. Beachten Sie bitte, dass GPS unter Wasser nicht funktioniert. Dies ist geräteunabhängig & eine physikalische Eigenschaft des Wassers. Entsprechend müssten Sie je nach Schwimmstil darauf achten, dass die Uhr immer ein wenig über der Wasseroberfläche ist.

    Sehen Sie daher zunächst die folgenden Tipps: Verbessern der Genauigkeit für Schwimmen-Aktivitäten im Freiwasser (offene Gewässer)

    Weitere Tipps & Tricks zu unseren Produkten finden Sie unter https://support.garmin.com. ...

    Basically saying that GPS is not working under water, so watch need to be at least a bit above water, and linking to a Garmin website. No question or inquiry to submit fit-file for further in-depth review etc. It is as if after DC Rainmaker has given his ok in his in-depth-review, Garmin doesn't care further. And apparently this problem also has the new Forerunner 955. And that open water swim with freestyle works is shown by other brands such as Suunto or the famous Apple Watch.

  • Yes, I have the new 955 and seeing these problems. Yesterdays swimrun was horrible, under half the distance vs. real distance for one swim. I haven't contacted support as my guess is that they instruct doing full reset and then maybe exchange the watch if problem persist :D Maybe they will follow these forums a bit and at least are aware of the problems.

    945 was utter crap also when released, loosing total swims while OW and swimrunning, now it works, so they will make things better in updates, but this new distance algorithm feels like something made to tackle the GPS issue and is causing more problems than solving with the new watches.

    I was pretty happy with 945 after the fixes and didn't even notice it was doing the same thing as the difference what I got with it was not so noticeable, but with 955 the difference apparently can be over half, so that's noticeable especially if your swim speed is 5:xx/100m and umm.. no that can't be right.