GPS failure in water

Hi fellows,
am I missing something or my fenix 5 sapphire has a problem ?
I tried recently to use the open water activity while swimming in a lake in northern Italy.
first it took so long to get the GPS "green" then I rest in a buoy with my arm outside the water and I catch GPS. ...
aftherthat i made some experience and it result that I cannot catch GPS under water, even a few centimeters. I also lost gps signal when I put the watch under water after getting the gps signal.
is my watch defective ?

Top Replies

Odie21 over 5 years ago in reply to Former Member +1

The timing just turned out to be lucky for you in your latest outdoor swim because Garmin specifically states that GPS (on wearable devices) does NOT work underwater.

I have the Descent Mk1 and it saves…

All Replies

0 PaddyDeng over 7 years ago

It's normal, GPS doesn't work under the water, my apple watch 2, Fenix 5 Sapphire & Fenix Chronos all have lost GPS signal as soon as I rest the watch in the water. It will regain gps signal when my wriest leave the water.

0 KrapfenKringel over 7 years ago

This is especially annoying in water sports and messes up the top speed. On one SUP session I had a top-speed of 90kmh because I fell in. With no way to manually edit the recorded GPS track this really messes everything up.

0 Dr Phil over 7 years ago

It might be annoying, but it's physics.

0 KrapfenKringel over 7 years ago

No its bad software, depending on the activity it could filter out unrealistic/impossible speeds automatically as error. Or Garmin should allow people to manually correct recorded tracks for this.

0 PubBike over 7 years ago

TomTom used to make a bluetooth GPS receiver.

A possibility would be for Garmin to sell a Bluetooth or ANT+ GPS receiver for swimmers to wear in their scull cap, and when detected, the external GPS is used for the watch rather than the internal receiver.

There would need to be a new ANT+ profile for GPS data.

0 mcalista over 7 years ago

No, definitely not defective. GPS radio signals cannot penetrate water, so it has to try to pick up a fix in the brief part of your stroke where your arm is above water. Most watches will struggle to give an accurate plot while open water swimming.

A couple of suggestions:

* Ensure you get a green GPS signal BEFORE you enter the water. (It's not clear from your post whether you did this before, or just when you were already in the water).
* If you have travelled 100km or more before your swim (as you might before a triathlon event?), have the GPS enabled 5-10 minutes beforehand to download the satellite orbit data specific to your new location.
* Try enabling GLONASS as well as GPS in the Open Water Swim settings. This can help in marginal conditions

0 Dr Phil over 7 years ago

ANT+ GPS receiver for swimmers to wear in their scull cap

Or, as has been said before, wear the device under your swim hat.

0 PubBike over 7 years ago

...yes but then wrist HR can't be obtained.

0 Former Member over 7 years ago

use GPS + GLONASS in your activity settings https://www8.garmin.com/manuals/webhelp/fenix5/EN-US/GUID-E03FFCFD-15AD-401E-A15D-715629C6DBF0.html

For actually measuring your heart rate you'd probably want to use a chest strap. Wrist-based optical heart rate is not 100% reliable on any device I've used so far. If you're serious about it I'd definitely get a chest strap for actually recording activities and just use the wrist HR for sleep tracking and 24/7 monitoring throughout the day if you're into that sort of thing..

0 mcalista over 7 years ago

...yes but then wrist HR can't be obtained.

I'm not a swimmer so I haven't checked this myself, but I thought that wrist HR was disabled in swim mode anyway (something to do with wrist slap as your arm enters the water?) - so you wouldn't actually be missing anything.