Swimming GPS accuracy of Suunto 5
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@tomas5 For those interested, I just checked an activity from yesterday where I did about 1km of openwater swimming halfway my trailrun, using the Suunto 5. I do have Ambit 2 and Ambit 3 watches too, but I never used those to track swimming as I don’t have the appropriate chest strap. Using a Wahoo as it communicates both in ANT+ and Bluetooth. Plus I like how you can switch activities in the Suunto 5. Indeed the swimming track looks jagged as if it only picks up a point every couple of seconds whereas the running track is smooth. It doesn’t bother me too much. Also because I’m not fast or efficient with swimming so the logged track is smooth enough for me ;).
In the attached picture, you see both part of the run and of the swim. And yes, I’m bad at swimming a straight line too ;).
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@vinay thanks for info, i think your track looks pretty good compared to main. I usually get fix only when i purposely stop and take my hand out for multiple seconds. I am swimming breast stroke only. So while swimming watch are close to water surface but rarely above surface. But i will do more of openwater swimming next next few weeks so I will see how it will work.
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@tomas5 Well yeah, could still be that swimming motion is different from mine. I definitely don’t qualify as a skilled swimmer and even though I’d love to call mine a breast stroke too, it may not look like that ;). But chances are I am actually dragging my arm deeper through the water so that may not be the cause. Would the kind of water matter? I was swimming on a small lake, so no salt water. Just trying to find out what the differences are. To be sure, I’m using the regular 5 which, just like the Ambit watches has the external GPS antenna. So not like the more recent 5 Peak which has the antenna under the screen.
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@vinay even a very thin layer of a few cm of water will fully block the GPS satellite frequencies. Remember: Civil GPS is using 1600MHz frequencies. These are microwaves, similar to those used ina microwave oven (2400MHz), where their only purpose is to be absorbed by water.
Plus the signal propagatino delay will be differenz under water. Since the whole GPS navigation is based on signal propagation times of a few nano seconds, this will also have an effect.
Conclusion (as said before): Forget about getting anything out of a GPS receiver if the antenna is not frequently lifted out of the water.
If you swim breast stroke, put the watch under your swimming cap or into a buoy etc. Everything else will result in random data.t6, S6, Elementum Terra, Ambit 3 Sapphire, Spartan Ultra Copper, Traverse Alpha, S7 Graphite LE, S9B Ambassador, S9P Granite Blue Titanium, S9PP Titanium Sand, Vertical All Black, Race Titanium Charcoal,
Race S All Black - TI Canary - Titanium Courtney -
@egika said in Swimming GPS accuracy of Suunto 5:
Remember: Civil GPS is using 1600MHz frequencies. These are microwaves, similar to those used ina microwave oven (2400MHz), where their only purpose is to be absorbed by water.
Ah cool, funny way to think about it like that, that’s for sharing!
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Is the GPS accuracy setting set to best? It’s also possible to combine navigation systems.
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@activejiggy
neither of these settings improve the fact that gnss signals don’t go thru water
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@egika Fair enough. You’d expect Suunto might come up with a swim-gps pod at some point. After all they also have a digital HR sensor that’s good for swimming. Putting the watch on your head or on a floater might solve the GPS issue, but you’ll use some functionality like measuring your cadence etc. Plus of course I’d be worried to lose the watch if it isn’t secured.
So yeah, you can move the watch to another place so you win some (GPS reception) and you lose some (cadence etc). I’m personally fine with the way it is now but for someone who values better GPS reception when swimming, a separate GPS dongle may be good. Might be nice if it also works for those with a Suunto 3.
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@vinay
the track is already reasonably good if you do crawl - freestyle swimming (?)… breaststroke and gps tracking basically doesn’t work at all for me -
@freeheeler Oh yeah sorry, I don’t know all the names in English. I do crawl indeed, no breaststroke. That might be the difference between our GPS tracks (as mine was reasonably fine).
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@freeheeler True, the best setting will sample every second though. Maybe it just needs a constant fix though.
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@activejiggy
it needs filtering as shown in the pictures… as I am not a swimmer, I prefer to do surfboard paddle training but most recently with open water swimming mode instead of SUP mode as previously… see the difference:SUP mode:
ows mode (I did paddle a triangle, not the exact way back):
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@freeheeler same session or different session?
Personally I did use and always use SUP profile so that you can get stroke rate, distance per stroke, along with pace -super useful for determining when you have caught a wave. -
@jamie-bg
that was a different session, I can not record 2 records in one session with one watch
for surfing there would be surf mode but I haven’t used it much and don’t know what it records.
for SUP I’ll keep using SUP, but for just surfboard paddle training, I’m going to use open water swimming -
So i was testing this a lot last two weeks. While breast swimming style, i must put my hand few centimeters above water and wait 10-30 seconds to get gps fix every time i want to record swimmed distance. It is sometimes hard to do if there are waves but it is possible. But after some time i just stoped doing it and recorded just openwater swimming without GPS. So i have just time and stroke. I think strome rate and time is more important than GPS track. Since there are water currents distance is less accurate tu measure work done.
