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Open water swim issue

Since few days ago, my 935 device won't measure accurately open water swim distance. It's basically an euphemism for won't measure at all. I swam today 2.5 km over 1 hour and measured distance was 3 m. Since two of my friends who own 935 also have the same issue for the last couple of weeks, I wanted to see if this is a common thing with 935. I don't recall any software updates that would be the root cause. Had an olympic distance triathlon race on Saturday and everything was fine then.

  • Either way, I recall 2.51+ on GPS version is basically when I personally started seeing worse tracks.  I think this roughly lines up with when most (that see the issue at least) note they devices got worse.  I just wish I could revert to 2.50 to see if it made a notable difference that I think I recall.

    I have been swimming the same lake 2x a week or so with my wife for the last 2 months or so and her fenix 6s plots fantastic paths while mine looks totally bonkers.

  • How can we revert GPS to a previous version ?

  • You can’t that I’m aware of.  With the beta releases they usually had the old stable firmware included but I don’t think you can drop that in the remotesw folder to downgrade from a non-beta version.

  • Another total wreck of a swim track...

    Purple and Teal are in a swim buoy, one a Vivoactive HR and the other an Edge 530.  The brown track from the 935 with GPS+Galileo.

    Total distance across is ~750 yds for scale / reference.  Total swam 1.3 miles, FR935 measured 1.95 miles.

    Maybe for fun I'll see if I can use my wife's fenix 6 on my other wrist.  Not an equivalent test given likely different arm motions but it could be fun to see.

  • My watch has suddenly recording about half of the distance I have done. I've not changed anything. All updates are on. My pace per min down by about half. Not sure why? 

  • Yes I agree. Suddenly my watch not recording distance properly.about half the distance I’d say. My pace has dropped by about half per 100m. And intensity minutes aren’t registering either.

  • So no correction for this?? A expensive watch and garmin will not fix this issue? i am having the same problem.

  • I've got the same issue with my 935.  Running 21.0

  • So,  I have commented previously on this matter. It really bugs me ! I've swum 285000m in the Irish sea over the last year.  I used to think the 935 was fairly accurate until I started swimming a 320m triangle course. Each time I do that,  the 935 underestimates by 20%. The track shows truncated triangles. I compared the track with a Locosys BT 31 in a swim buoy. I was astonished that over a 23 minute swim  the 935 only recorded about 25 data points. The Locosys recorded over 2000 points Garmin boast that the 935 has an algorithm that takes account of  the break in gps signal each time you put your wrist in the water.  It doesn't seem to work.

    Straight line swimming fairs OK because you only need 3 points to be recorded: start, turn around and end data points, to get accurate distance and therefore pace etc.

    I contacted Garmin who gave me a replacement unit. Same issue. 

    I've tried all the different GPS settings. Updates, blah blah. Maybe the new Apple watch will be better.  I'm really disappointed that a €550 Garmin is so inaccurate.