Recording extreme dives, ceiling top option & other issues

Nacho Etche said:

During my first diving trip to Patagonia with the descent I experienced a huge problem with it. After 3 days and 6 single gas recreational dives I was drinking cofee during the afternoon when suddenly the diving mode started and recorded a 57 seconds dive at 97 meters!!!!!!! I was shocked, so the next day I called the distributor who sold me the descent, told them what had happened and that I would not dive with that particular computer again and a couple of days later they gave me another one. I asked them several times to send the malfunctioning computer to a official garmin service in order to get an answer regarding the problem but instead they shipped it back to Asia. I also phone called and sent emails to garmin, describing my problem and never got an answer,still waiting for one!!! Given that I´m a dive instructor I needed to continue using the computer for work (my old suunto was not working) so I decided to keep the descent although I am extremely dissatisfied with the product and the company. Anyone experienced a similar problem? 

This sounds like a failed pressure sensor.  I have seen a couple of reports of Mk1s with this issue.  The distributer replacing it was the right thing to do.

I think I have seen reports of faulty pressure sensors from just about every brand of dive computer, including Shearwater.  Things fail.

Nacho Etche said:

That said, I also used the descent for tec diving in Chile - february 2020. Overall I was happy with the perfomance of the descent, did several deco dives at around 50 meters with 3 different gases. But i was particular upset with the fact that you cannot set a ceiling top for planning decompression stops (shearwater has that option). So if you plan using O2 (1.6 PO2) during your last deco stop, the descent sets the ceiling at 3 meters when you can be doing it at 6 meters! I know that you can still do the stop at 6 meters, but then you are not following your dive plan by far. Also, doing a deco stop at 3 meters is way harder than doing it at 6 meters. As I mentioned, other diving computers have the options of setting a ceiling top and it would be a great add on for the current descent software.

I agree this is something that should be added to the Mk1 (and Mk2 models).  Hopefully, Garmin will take that onboard.

Nacho Etche said:

To finish, I believe that the deco stop watch (during a deco dive, bottom left of the the screen) given in minutes and seconds, that updates if you ascend or descend, is really confusing. To illustrate, if according to your dive plan calculated with the descent you have to do deco stop at let say 15 meters (It does not use the ceiling top, just a theoretical stop at a given depth given your profile) the descent shows you a timer in minutes and seconds that is constantly updated, so you can do a shorter shallower stop or a deeper longer one. Other diving computers I used, specially the shearwater, just show you the minutes and the depth for a given stop, normally deeper than the descent, and this stop does not change if you ascend or descend a bit. So I think that garmin tried to used a more complex approach but in the end is more confusing.

I very much agree with you on this and have complained in this forum.  It doesn't give you specific deco information like most other dive computers but simply "time to surface" which includes ascent time AND deco.  It is very confusing.

By the way, your English is fine. 

atj777 said:

I think I have seen reports of faulty pressure sensors from just about every brand of dive computer, including Shearwater.  Things fail.

I can understand things fail (several people told me about malfunctioning pressure sensors in their diving computers), but dissmising the issue by sending the computer back to Asia without the proper analysis by proficient technicians and disregarding my emails and phone calls are not good costumer service habits. I expected a much hands-on service by Garmin. 

Great you agreed on the ceiling top and the deco watch, hopefully Garmin takes note of this.

I would like to add two additional questions I have regarding the descent I forgot to mention in the post above:

1) RMV (Respiratory Minute Volume): Other dive computers allow you to set your RMV which is extremely usefull for gas consumption calculations, specially for tec diving. I think you can manually calculate this metric by editing your dives in the garmin connect app. But I don´t know if you can then can use this metric in consumption calculations in your dive plan, which is not an option actually. 

2) This following issue has been probably adressed many times! Is it possible to erase dives from the descent logbook (not garmin connect)?? I have recently been diving in a quarry with almost no visibilty, certifying OW, and after two days I recorded 30/40 shallow dives, many of them of less than 3 minutes. I did not forget to set the descent in pool mode, which I often use, as some of those quarry dives need to be logged. My point is that if every time I go to the quarry I log 40 dives, in couple of months I will be using a lot of the computer´s memory for logging. 

Thanks

Use SubSurface instead of Garmin Connect, it allows you to group multiple dives into a single dive. It is possible to connect the Descent to SubSurface, though I use mine as a backup so I have only tested this once and use the data from my Shearwater. 

Nacho Etche said:

I can understand things fail (several people told me about malfunctioning pressure sensors in their diving computers), but dissmising the issue by sending the computer back to Asia without the proper analysis by proficient technicians and disregarding my emails and phone calls are not good costumer service habits. I expected a much hands-on service by Garmin. 

Why do you think that sending the computer back to Asia is “dismissing the issue”? How do you know that sending the computer to Asia wasn't the process for analysis?  Are you suggesting that proficient technicians don't exist in Asia?

What did you expect Garmin to do?  They replaced the fault dive computer with a new one.  All good manufacturers would do this.

Nacho Etche said:

1) RMV (Respiratory Minute Volume): Other dive computers allow you to set your RMV which is extremely usefull for gas consumption calculations, specially for tec diving. I think you can manually calculate this metric by editing your dives in the garmin connect app. But I don´t know if you can then can use this metric in consumption calculations in your dive plan, which is not an option actually. 

I’m not sure I understand what you mean.  Are you suggesting you tell the computer what your expected RMV before a dive and it will use that for gas consumption projections during the dive?  I don't think I can even do this with my Shearwater and that is air integrated.

Further, I find that my RMV varies greatly from dive to dive based on various factors including temperature, current and surge.  The average RMV for my last 6 dives varied from 11.2 to 14.2L/min.

Or do you just mean calculate the RMV after the dive?  Yeah, Garmin Connect won't do that for you, but then Shearwater Desktop won't either.

SAC and RMV are easy to calculate especially if you use metric units.  Third party dive logging software, such as Mac Dive and Subsurface, will calculate RMV for you.  Both of these support the Mk1.  Note that Subsurface calculates RMV more accurately based on the fact that air does not compress linearly.  This will give you lower values than a manual calculation or from other software

Nacho Etche said:

2) This following issue has been probably adressed many times! Is it possible to erase dives from the descent logbook (not garmin connect)??

Yes.  Connect the Mk1 to your computer using the supplied USB cable.  All the activities recorded on the Mk1 are in the Garmin/Activity directory.  They are named based on the date and start time of the activity.  You can delete the ones you don’t want.

Nacho Etche said:

My point is that if every time I go to the quarry I log 40 dives, in couple of months I will be using a lot of the computer´s memory for logging. 

My Mk1 has well over 200 activities (dives, runs, etc.) and that takes up 18MB of storage.  Each dive is 100-200kb (my dives are 90-120 minutes).  I have over 11GB of storage remaining.  If I assume 200kb per dive, I have space for over 50,000 more dives!

I doubt Garmin ever determines the exact failures to the component level, the cost of doing so it quite high and they can pretty accurately determine it was the depth sensor with a quick test. Tearing down the Descent is probably not cost-effective in most cases, cheaper to just replace it and scrap the failed unit. The reality is most consumer electronics are not designed to be repaired, or in a lot of cases even dismantled. 

Tried but could not sync it! I will keep trying as I cannot use the garmin connect mobile app as my phone (motorola) does not support it.

atj777 said:

Yes.  Connect the Mk1 to your computer using the supplied USB cable.  All the activities recorded on the Mk1 are in the Garmin/Activity directory.  They are named based on the date and start time of the activity.  You can delete the ones you don’t want.

This works great.