FR945 swim map vs swim distance (GPS Issue)

The problem with watches losing GPS early on in a swim and even during a swim was present on most of the watches when they were first released with the Sony chipset but not sure it’s an issue anymore. Or put it another way, it’s nothing I’ve experienced this season. It is clear that the watch will ‘catch up’ if you stop somewhere along the swim and allow it reconnect properly to the satellites. That’s hardly surprising given the very sketchy connections it’s had while you were swimming but I am finding now that is usually only a few meters, not the 10s or 100s from earlier.

 I don’t agree that the Sony chipset is bad for accuracy either. I think what we see with the swim tracks is an increase in sensitivity that is not being handled well by the algorithm used to map the swim path taken. If you compare the swim track form a 935 or an Instinct (not sure if that has the Sony chipset) the track does look smoother. And for other activities I can easily demonstrate that the Sony chipset is at least as good as the earlier chipsets with runs over the same course dating back to the 310XT.

After another swim (and again a perfect track), only two candidates are left for the messed up measurements (for Swim2 at least, but the software and the problem is the same for FR945). One is still Physio TrueUp (but I tend to agree that it has no effect at all), but the most possible candidate is bluetooth. 

So for everyone experiencing massive over measurements of distance and weird tracks, please switch OFF bluetooth connection next time before you start OW swim and measurements. I know that for most of the people it is constantly on. For FR945 it might be a good idea to switch OFF wifi as well (Swim2 does not have wifi, so I do not need to worry about that)

My first 6 OW water swim tracks were a mess, always the same symptoms (and I am sure that for all of them BT was on), now the last 2 tracks are extremely good - and today BT was off, and I do not remember how it was last time. I am sure that the Sony chipset is very good for accuracy. Only some settings need to be checked.

My BT has always been on and remains on.

I was sure that you will disagree. Anyway, I shared my results, everyone does what he/she wants. If no BT and no Physio TrueUp (red herring or not...), the remaining options for others is to switch off every unnecessary metrics/red herrings in the watch to spare on computing resources. The OW swim software seems to be working well if watch is not overloaded.

With Swim2 I am happy now, for FR945 I stopped troubleshooting :)

PG said:

I was sure that you will disagree.

It's not a question of disagreement. It's an observation. You are free to hypothesise just as I am free to offer my observation that I generally have no problems with the swim tracking with those settings on.

As noted, the occasions when I have had poor results have usually been after an update. The poor tracking has then resolved itself once Garmin issue a subsequent update without me changing any settings on my watch in between times.

It is a good thing that you raise a red flag against my theory. It's the way how you do it...

Remember, this poor tracking (again, SAME issue for Swim2 and FR945) was resolved for me WITHOUT any Garmin intervention, no updates, nothing. And as you can see, Garmin has not the slightest clue about this problem (support is useless completely), most probably they can not reproduce it in test environment if the root cause is capacity limitation. You are lucky, that your settings do not cause the issue.

Anyway, the symptoms are not always visible in map track, it is much more visible in pace chart.

Anyone is free to play with the settings and experiment. If you and your watch are fine, than why bother.

I agree with you on how to experiment with garmin swim 2. I have had this problem with garmin 935, chronos, 5X ... Thank you

Hi, I seem to have exactly the same issue with my new 945, software is the latest. I had a 920XT for several years, it's been faultless but the 945 swimming the same locations doesn't track the route, just the furthest point to point and no record of loops. Distance appears to be correct but pace is suspiciously flat. Can I ask if you resolved this issue? Thanks

I can tell only from Swim2 perspective (it has the same Sony chipset and the same OW software, but much weaker HW).

With Swim2 there is a bug somewhere in the settings, what can destroy the OWS tracking completely and always. I managed to set my watch to eliminate this issue. But the watch still loses GPS signal sometimes, and if it does, the track and measurement are terrible.

For me it seems that Garmin still needs a lot to work on handling the Sony chipset well, and eliminate occasional slow recovery from GPS loss. Sometimes it loses the signal just for some seconds (recovers during swim), but sometimes the watch needs about half a minute stable view to the sky to recover from the loss (meaning that recovery during swim is impossible).

So check for GPS updates and hope for a fast solution from Garmin.

Thanks, at this rate they'll be getting mine back pretty sharpish. Very disappointing that tech several generations newer works nothing like a good as the old tech and that it's sold with such obvious defects ️