Swimming distance / laps

The same accelerometer measurements are used to determine stroke type/counts as well as lap turns and the other stats. Problems with lap counts tend to arise from interruptions or stroke discipline. When the battery lasts (won't mention that), my VA3 has been deadly accurate with lap counts from day one. That being said, on the occasions I have had to pause mid-length due to a slower swimmer in front the momentary stop/start will definitely register as an extra length. This is clearly visible in the breakdown after uploading the activity to Connect. Similarly, changing stroke mid-length will likely confuse it into counting another lap. Conversely, 'missed' laps are often the result of a weak push off when starting the lap: the sudden change in direction is what triggers the count. There are a ton of other threads on this topic too. hope this helps...