Did anyone noticed inaccurate with lap swim with this watch? it seems that it always adding around 20% of what I actual swim. do you have any ideas how to solve it? cheers Yair
Pretty certain the results you are experiencing are not specific to the 645M. Read some of the posts from this search - swimming accuracy What stroke(s) are you swimming? Are you swimming lengths without any interruption? What do you do at the end of each length?
It counts laps with accelerometers. So suddenly speeding up to pass someone or slowing down will add lengths. Also fidgeting on the wall between laps (press the lap button at the start and stop of each length to avoid this). The search results above have other suggestions as well. I find the swim function on Garmin watches 100% accurate unless I don't follow these or have a mid-lap interruption.
