Does anyone have an algorithm to detect swim laps using the accelerometer data?

Check the elapsed time for the activity.  Could it be you are repeating the same thing, like swimming laps?

No, I've verified that the input data from the fit file is repeated by reading out x, y, z in my debug console.. my fit activity is about 25min however only the first 30-40sec are used then repeated... weird... I've been exporting to excel and plotting looking for patterns and trends when a lap would occur... but I only get enough time for one lap.. 

I've used my own fit files in the sim for years, but not for swimming.

One thing is there is a difference if the fit was recorded with every second or smart recording, as "smart" can jump a few seconds at a time.

My datafield seems to work well. I use my Forerunner 955 watch.

Had not seen this in store, maybe due to v3..

Does it save the hr data in fit?

Will you expose how you detect laps?

Thanks