Open water swim performance of FR965

I'm interested in this topic as well. I found the accuracy of the 945 for OWS to be so-so, it lags behind at least 20-30s, which is quite annoying when changing directions or stopping for a rest. Would be curious to learn if the 965 is any better since the GPS has been significantly improved for running and cycling according to reviews.

It might depend how you swim, for me it does not work well.

First thing is that I like breaststroke, and with the watch being under water almost all the time it has no reception. I also use freestyle and backstroke from time to time, where I would expect it to work better. And the watch does measure position for those stokes, it's still quite inaccurate - position measurement seems very noisy, which is clear when you pretend an outdoor pool is open water :-)

Finally, I do change my pace drastically - or even stop - during my swimming, and the watch does not respond to it well. I could understand that it tries to make some predictions assuming I just continue at the recent pace, but then would expect corrections when an actual position is measured. Either this is not the case or the position measurement noise makes it all fail. When I swim in an outdoor 25m pool and so know the distance, the distance measured by the watch is often ~50% on top of it.

By the way, the pool swimming distance measurement also does not work for me (or others in my family who tried), as it tends to split some lengths into two in quite nonsensical manner (which would require me to suddenly double my typical swimming speed without an apparent change to my heart rate :-)

I wouldn't expect OWS to work for an outdoor pool workout, since GPS accuracy in general is around 1-2m under ideal conditions, which is definitely not the case while swimming. So with a 25m pool you are definitely already in the error range of GPS.

Also, I understand that measuring swim distance with *** stroke will not work unless you stop for GPS signal at least at the corners of your swim route.

However, I'm curious to hear how it performs for freestyle swimming in a lake. From what you describe, it sounds pretty much similar to the 945. The lag is a common problem of the interpolation, which makes it hard to be used for any workout that has pauses and/or turns. However, if it really measures more or less than the actual distance in spite of better GPS info, that would be bad. The 945 had a bug last year when it measured consistently 30% less than the GPX track reported, so maybe another SW problem in the 965.

For the pool distance measurement, do you have any comparison with the 945? I found it to be fairly accurate for all sorts of swim styles. It only failed on technical trainings for me, but that's to be expected as well, and there is a recording mode for that purpose.

When I am cycling, the GPS accuracy is spot-on. When I stop, it detects that I stopped within a second or so (it auto-pauses the activity for me). When swimming, it does not detect that I stopped at all. It keeps adding to the distance even when I hold on to something or stand in shallow water, with the watch being completely out of the water and with perfect view of the sky (or at least way better than what it typically sees when I am cycling). So with multi-channel GPS, large outdoor pools and me making sure that I keep the watch above the water whenever I stop, I am not convinced that it's the GPS accuracy which makes the distance to be inflated by 50%+ compared to what it should be.

I didn't use my 965 in a lake yet, but I did use it both in large outdoor aquapark-style pools (for example swimming in large circles) and in regular 25m pools (swimming there and back). In both cases the distance was seriously overinflated. I didn't compute the distance myself from the GPX track, but the track itself looks rather poor. Not a disaster, but shows both missing data (misses some parts I clearly did) and position wandering (regularly leaves water boundaries and there is more there-and-back than I believe I did) - clearly worse than for my cycling paths. If the distance estimated from this noisy track was 10% off, I could understand and live with it. But it's way more.

I have no comparison to 945, only to Venu 2 Plus. Both are practically unable to distinguish my freestyle from my backstoke. I don't think my style is *that* bad ;-) They also split my pool lengths even when I make sure I have a strong kick during start/turn, coast for about two seconds with no strokes and then continue without stopping until the next turn.

Well if the FR965 reaches a similar result like the FR945 with Freestyle in a lake or in the sea I'd already be happy.

That wasn't the case with the FR955. With the FR955 my usual pace dropped by about 50%.