Issues with temparature sensor?

Hello lovely folks!

Sorry to bother, just got the amazing Mk1, very happy with it!

However, today I tested it for the first time for a snorkel/freedive, and I am afraid there is a temperature sensor issue?

I've noticed by looking at the post-dive data that temperature acquisition remained all constant at an early stage of the session, once it got to 16 degrees C it stayed like that through the rest of it, and that was not the case for sure! I was wearing the watch on my wrist straight in contact with the skin in Apnea mode. So i wonder if there is an issue with my sensor and if I should look into a replacement or something?

I've enclosed a picture on how Dive depth, heart rate and temperature vary!

Any suggestions or observation appreciated :) Thanks a lot for your attention.

0 atj777 over 3 years ago

Do you think that the water wasn't 16ºC fro that period?

There is a known problem (that has been fixed twice and reintroduced again) where there is a difference between the temperature displayed during the dive and the temperature in the log. I have found that the temperature is the log is quite accurate.

0 trux over 3 years ago

Emiliano said:
Any suggestions or observation appreciated :) Thanks a lot for your attention.

As atj777 wrote, it looks all right, although we do not know what the true water temperature was. What exactly do you find wrong? If you expect that the sensor captures your body temperature, then in water it is not the case. Water's thermal conductivity is 24 times higher than air's (0.6 vs 0.025 W/(m·K)), which means heat moves easier in water, acting thus much stronger than in air, on the temperature sensor. In air, the body temperature influences the sensor reading greatly, because the thermal conductivity of air is not big enough to bring away the body heat from the sensor. Opositely, in water, the body temperature has minimal impact on the reading, because the body heat is conducted away very quickly (unless you have the watch under a neoprene sleeve). Basic physics.

0 Emiliano over 3 years ago

Thanks a lot both for your inputs! :)

I am more worried about the temperature variability in that stretch rather than the actual value. 16 sounds about right for most of the snorkel, but why it stayed constant? I am pretty sure temperature went dramatically up again when re-approaching the shallow water near the shore. But that did not show up in the last stretch for example.

I am expecting the sensor to capture water temp, not my body one of course!

Cheers

Emiliano

0 trux over 3 years ago in reply to Emiliano

Emiliano said:
I am pretty sure temperature went dramatically up again when re-approaching the shallow water near the shore.

Well, it is hard to guess, if you did not have any other thermometer with you to compare it with. The subjective feeling is often very wrong. Also, the temp sensor is quite slow, and it may take up to several minutes before the temp change is recorded.