Fitbit Sense swimming

[TimothyWillian]

I was a happy Fitbit Ionic Adidas version for many years until it was recalled. I was especially pleased with its app for swimming. It could faithfully record my swims of 1 km in a 25 m pool and gave the correct lengths and times in minutes and seconds. I bought a Fitbit Sense 1 with the refund money and have found that it cannot match the prevous watch. I now have to count my laps and swim in 250 m sets because the watch cannot accurately measure distances. Mostly it overcounts in a strange way, with 100 to 200 meters over the actual distance of a 1 km swim. In addition the summary on my phone rounds up times to minutes only, giving 5 min for a 250 m swim that was actually 5 min 10 seconds. However, using my computer to access the Fitbit website, the dashboard gives the times in minutes and seconds. Why not the watch? The times with the Sense are correct but the distances are not always correct. Even when I swim in 250 m sets, the watch sometimes reads 275 or 300 m for 10 laps that are confirmed by the time, which is always correct, to be only 250. This is frustrating for me, since I formerly concentrated on my non-stop 1 km swims and smply looked at the watch to know when it was complete. The Sense is OK for walking and running. 

[Allorb]

I also regularly swim a km in a 25m pool. The Sense frequently undercounts lengths by one length. Never had it over count lengths. I'm aware of this, as by habit, I count the lengths mentally, as I did prior to getting the Sense.

[TimothyWillian]

Thanks for your comment Allorb. I swam yesterday, 8 sets of 250 m each in about 6
minutes each. All 8 were logged this time with one coming out 275 m and all
the rest 250. With respect to under-counting, I used to get this sometimes
with my former Fitbit Ionic but found out that if I waited just a few
seconds at the end of the lap before hitting the stop button, it added the
initially missing 25 m. You might try this with the Sense. I am still not
happy that the time record on my phone doesn't show seconds but rounds down
to 5 min even for a 250 m set that was actually almost 6 min. I also had a
problem with the Sense that it didn't record all of my 8 sets each time.
Sometimes only 4, sometimes only 6. I realized yesterday that it may be
that I need to sync my watch with my phone before any long exercise like
swimming, walking or running, to be sure that the watch memory doesn't run
out of storage space before I finish my exercise.

[t.parker]

I found one solution - stopped tracking swimming with any Fitbit. Instead, I track it with a different, more reliable device and just sync it into my Fitbit account. This way I get a record in the Fitbit account (which anyway is worthless as Fitbit's swimming support is a joke) and lots of other data and accuracy in another platform. Additionally, I don't risk water damage of Fitbit.