'Data recording' option for open water swimming

So for me the issue is that the 935 is just not getting or processing the gps signal quick enough when my wrist is over the water.  I think it was more accurate with older software versions but I am not 100% certain of this. 

Yes, I don't like using the buoy. The 935 is marketed as a watch that is good for open sea swimming. I like the stroke count, the lap function and temperature function but if the GPS  distance is inaccurate its all worthless data!

Couldn't agree more, guy_mx99. It's no longer OW season where I live anyway, so I am not quite as annoyed as I am each June to September. I stay with Garmin out of sheer inertia. I'm used to the web and mobile interface, all is nicely synced to Strava and Training Peaks, but this OW weakness can't justify my loyalty much longer. Does anyone know if other Garmin models are **good** at OW?

The best for open water swimming is 735. The 935 measures 10%-15% less than 735.i have 735 2 years and i have swam a lot of races and gps working very good. I bought 935 and I m wearing both together and the measurements are very different (10%-15% less the 935). Also the pace. The diagram on garmin connect with 935 it cuts corners. I hope to find the way to fix it in garmin with an update. 

I'm afraid I'm not talking about 15%, Lefpan, or even 25% as guy_mx99. I'm talking about utter rubbish, like data points way out on land, bringing distances to a double, and speeds like mach 3 to jump to those points from the water...

Garmin must update the gps. They have to find a newer version otherwise the watch will not be able to record true distance. Maybe they can take gps data similar to 735.

What I have noticed is that the 735 counts more slowly than the 935. At a distance and as the meters go up, the 935 goes up at a slower rate.

2.60 was fine, previous version was really bad.  But 2.70 on OWS shorten a little the measure about 5-10%

Agreed.  It kind of ruins the benefit of the 935 watch.  I could just buy a cheaper gps watch.

I continue to be frustrated with Garmin's inadequate OWS.

I routinely have to edit each swim and add distance. I only use the watch for laptimes on a course I use.

I have discovered that the OWS activity does not record many data points compared to other activities.

For example, yesterday I  paddled my SUP  with my 935 set to RUN activity to measure the distance around a local triangular buoyed swim course.

The 935 recorded 340 points in 5 mins in Run mode. It gave a nice smooth course  .Run track vs Open water track.docx

I then swam around the course 4 times in OWS mode. It only recorded 48 data points in 38 minutes!!!

See the attached doc.

OWS mode will never be accurate if the GPS receiver is only managing to get barely more than one data point per minute.#

Before someone asks. Yes the data was set for recoding every second on both modes.

Sorry to hear that, guy_mx99, I bought a forerunner 745 about a month ago, for other reasons really. The temperature readings of the 935 were completely off, steadily increasing, recently 80 degrees Celsius on the wrist (180F) and 60 in the air (140F) - and there is no calibrating. The elevations on my runs had always a considerable drift (come back home  a couple of hundred meters higher than I left...) And it froze sometimes for no apparent reason.
I haven't tried the 745 in OWS as we only have 9 degrees Celsius in the fjord down the street here (48F). But the elevation on the runs is much more stable (actually spot on).

I'll post as soon as I try OWS, could be this week, as soon as we pass 10 degrees Celsius (50F).

I know it is controversial, but I had good results with wrist HR in the pool (tight wear). The reading are reasonably smooth (jittery, but no big jumps that can't possibly be physiological). The range matches what I used to have with a chest strap. And the curve matches the training intensity well.