Watch stops recording distance during activities

support.garmin.com/.../

Hmmm, ok, doesn't make much sense to me, but I'm curious to see the results. Anyway, I use smart recording all the time, and my open water swim tracks look quite ok. Never experienced issues with distance recording being aborted.

I use smart recording too as the fit files are much smaller and battery charge lasts longer. But think of it like bread crumbs. The more you leave the more exact resolution of the trail path. That said, as I agree that smart recording would not affect whether or not one loses the GPS signal. It would only slightly decrease the recorded distance if there are any short deviations from a straight line (zig zag) or a turn around without pausing a few seconds with the hand above water.

Andy275 said:

It would only slightly decrease the recorded distance if there are any short deviations from a straight line (zig zag)

No, it would not, because smart recording affects only what is stored in the fit file. GPS sampling and resulting distance calculation are in 1-sec intervals, no matter what setting (unless ultratrac is used, but that's another story). Distance is not calculated based on what is stored in the file. It's based on what comes from the GPS chip, and that always works in 1-sec intervals.

Andy275 said:

or a turn around without pausing a few seconds with the hand above water.

Ok, sure, but again this is an inherent challenge with open water swimming, and enabling 1-sec recording won't change the frequency of GPS sampling.

I haven't tested it scientifically, but my experience on one frequented point-to-point OW course is that with smart tracking the recorded distance is less (5-10%) than the distance on Google maps or than when I record every second. While it may read the GPS signal every second, from this post it would suggest that what you see in the mapped track is what is used to measure distance. support.garmin.com/.../ Frankly there are limitations of the technology inherent to OW swimming as you said since the watch is under water much of the time, and knowing that, I can live with this error. Just my anecdotal experience--admittedly I am surmising from that and Garmin and other sites that the recording frequency does affect distance. But I am happy to be wrong as I use smart recording since it is good enough for me.

Yeah, well, the tricky part with open water swimming is that unless you keep your watch under your swimming cap, accuracy will be impaired, no matter what settings you use. And since it is not easy to compare two open water activities - one with smart recording, and another without - then we're left with speculation, mostly. My understaning was that the result of smart recording - smaller file size aside - was somewhat smoothed track on the map, and that's all. But now you made me thinking if things are not slightly more complicated.

Agreed. If one really cares then the swim cap/buoy method would be optimal. But if it is more complicated as we suspect, the smart recording would still impact that approach. Besides Garmin just telling us (which I doubt), it could be tested on land with a zig zap course vs a straight point to the same location. Even there one would need to control for velocity as smart recording supposedly is triggered by changes in direction and velocity. I'd need a robot and motivation to test that. ;-)

Ok, perhaps I am wrong. I compared twice the displayed meters in a 1000yd point to point and the distance measured under smart and 1-sec recording were very similar (within 20 yds). So perhaps it potentially matters only when there are turns or non-straight paths. Interestingly today I noticed with smart recording (my default) toward the end of a 4500yd OW swim that it had stopped recording at ~4k, but then when I paused the swim with my hand above water, it quickly incremented to the seemingly correct distance. It drew a straight line between the 500 yd points interpolating the value.  It work well since that portion of the swim was relatively straight.