Garmin Descent MK2

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I would like to learn more about the circumstances on these dives. I've conducted more than 50 deco dives using my old MK1 and I've never seen anything more than a few minutes of difference in the deco schedule between the MK1 and my Perdix.

Without knowing anything about the dives, it's conceivable if one didn't enter their deco gas correctly, you could easily have several hours of deco assuming one did 60 minutes at 130 feet on air and the computer though you'd be deco'ing out on air.

I find it quite a capable tech diving computer, and I'm saying this as someone who has no financial interest in the sales of these computers.

Tony

Although I did only a bunch of deco dives (something like 5), I share your thoughts.

Also, diving mode starts automatically, and if you forget to set the watch properly before a dive, you'll have troubles... which I don't like

It would be surprising if a respectable company like garmin would put on the market a device conceived for tech dives, which is not reliable for its job...

Note: that doesn't mean that mk1 is a good computer, I have it and I think quite the opposite....
 
@stuartv, I'm not certain if anyone has answered your question, yet. (There are still 10 pages of posts to read to the end of the thread and I'll lose my train of thought if I don't reply now.)

So, I like the idea of the Descent Mk2i. I was also not aware of the cost differential between it and the Fenix 6 & Teric you pointed out. Thanks for that.

I don't know which direction I'll go, however, (for me) the advantages of having all my biometric data in one location comes from a vantage point of me as a system rather than piecing out individual components.

For example, while I do find it useful that to analyze my cadence, speed, power, and heart rate while I'm on my bike ... and to analyze my cadence, speed, and heart rate while I'm running ... each for their own purposes to help me better understand how I can improve in those specific arenas ... I also find it useful to analyze systemic changes over time ... and, maybe, why.

Of course, it's about as difficult to view two or three apps for that data as it is to insert an extra step to download dive data to Subsurface ... half of one, six dozen of the other.

Hey, thank you for taking the time.

I can see where having all the data in one app is an advantage - IF the data is the same kind of data. Like, cadence, speed, and heart rate. I can where it would possibly be nice to have that in one place for running and biking. But, what data is there that is really in common between diving and the other activities, that makes it nice to have it all in one place?

I will say another poster did make an effort to answer my question and I could understand his answer. As I took it, he would do a hike to get to a dive spot, then dive. So, having it all in one app meant that he could see his full GPS track from (presumably) wherever he parked to the dive site, and then the dive info. No need to switch to another app and look through the dive log for the matching date/time. That seems pretty niche, but at least it is an example of a convenience to having dive data in the same app with (in this case) hiking data.
 
I would like to learn more about the circumstances on these dives. I've conducted more than 50 deco dives using my old MK1 and I've never seen anything more than a few minutes of difference in the deco schedule between the MK1 and my Perdix.

Without knowing anything about the dives, it's conceivable if one didn't enter their deco gas correctly, you could easily have several hours of deco assuming one did 60 minutes at 130 feet on air and the computer though you'd be deco'ing out on air.

I find it quite a capable tech diving computer, and I'm saying this as someone who has no financial interest in the sales of these computers.

Tony

Yes, a few minutes of difference is not a concern. Even my Predator and NERD sometimes have a slight difference to each other. I attribute that to my Predator being on my wrist and maybe 1 foot deeper most of the time.

The questions about the Descent and tech diving would be:

Can you change the gradient factors during a dive?

Can you enter a new breathing gas and start using it during a dive?

Why would you want to do those things?

Example: I'm diving with GF50/80. During the dive something happens and I decide I need to get out of the water with the max safe speed. So, I want to change my GF to 95/95.

Example: I did a deep-ish CCR dive recently with a buddy. He had an AL80 of 80% for his bail out deco gas. I had an AL80 of 50%. If I had had to bail out, and, for some reason, I lost my 50%, I could have added the 80% to my computer during the dive and then breathed off my buddy's bail out deco gas, if I needed to. In reality, what I actually DID, was program his 80% into my computers, so that they were already in and turned Off. That would have allowed me to switch to it without having to go through entering the actual #. But, if I had HAD to, my Shearwaters would have allowed me to program in the gas and switch to it, during the dive.

If the Descent does not allow both of those things, then those would be reasons to choose a Shearwater for technical diving.

Oh, and does the Descent show the equivalent of what Shearwater calls "SurfGF"? The addition of SurfGF to the Shearwater computers has been a really nice thing (in my opinion)! I use that on pretty much every dive.
 
Also, diving mode starts automatically, and if you forget to set the watch properly before a dive, you'll have troubles... which I don't like

This is my single biggest complaint with the Descent, which I wrote about.

Can you change the gradient factors during a dive?

Yes, both high and low, although I've not experimented a great deal with this, and how it affects your profile. I just saw you could do it.

Can you enter a new breathing gas and start using it during a dive?

Yes, and you can even do this in the single-gas dive mode. Example, I wear the Descent when I'm serving as a hyperbaric chamber attendant. The sessions for the attendant are usually 1 hour, so 60 feet for 1 hour breathing air will result with me in deco. As we rotate out of the chamber, we breath pure O2 for the ascent in the lockout chamber. I can add O2 in as a gas and switch to it during the 'dive.'

Oh, and does the Descent show the equivalent of what Shearwater calls "SurfGF"? The addition of SurfGF to the Shearwater computers has been a really nice thing (in my opinion)! I use that on pretty much every dive.

No, these it will not show.

I tried not to compare the computer too much to the Teric, but as I write before, I get many questions as to how the computers match up. The lack of the SurfGF, @ + 5, GF99 (etc..) is one of the reasons I say just from a diving standpoint (excluding the fitness features) the Teric is a better dive computer.

For me, I dive with the NERD2 as my primary, so the Descent serves as a backup computer. I'm I'm doing a planned 60 or 100m dive, I'll also wear my Perdix.

For entry level into tech diving (40m with limited deco) it will serve fine as a primary. As one advances through the tech classes, my suggestion would be to get a Shearwater as the primary, and the Descent will serve well as a backup.

Tony
 
I tried not to compare the computer too much to the Teric, but as I write before, I get many questions as to how the computers match up. The lack of the SurfGF, @ + 5, GF99 (etc..) is one of the reasons I say just from a diving standpoint (excluding the fitness features) the Teric is a better dive computer.

For entry level into tech diving (40m with limited deco) it will serve fine as a primary. As one advances through the tech classes, my suggestion would be to get a Shearwater as the primary, and the Descent will serve well as a backup.

Tony
Thanks for addressing that. I’ve been writing out my stops on my forearm tablet from the dive planner using a Citizen dive watch for back up to my Perdix AI. I ‘m looking at upgrading. But no @+5, SurGF, or GF99 is going to take some consideration. I really like having something I can jog,swim, workout and dive with. The tides and having a GPS fix for dive site is nice as well. But lacking those calculations is a minus for sure.
And what about the battery and battery change out? Is it like the Garmin exclusive power pac deal they do with their hand held GPS units?
 
I would like to learn more about the circumstances on these dives. I've conducted more than 50 deco dives using my old MK1 and I've never seen anything more than a few minutes of difference in the deco schedule between the MK1 and my Perdix.

Without knowing anything about the dives, it's conceivable if one didn't enter their deco gas correctly, you could easily have several hours of deco assuming one did 60 minutes at 130 feet on air and the computer though you'd be deco'ing out on air.

I find it quite a capable tech diving computer, and I'm saying this as someone who has no financial interest in the sales of these computers.

Tony
Ditto here. I have probably done 10-20 dives with my Mk1 where I went into deco. While the deco requirements are not that intuitive compared to my Perdix, the times were within a minute of the Perdix!

The only time the Mk1 gave me a long deco was a dive I did with EAN32 but the top right button on my Mk1 was broken so I couldn't set the O2 mix. It thought I was diving on air. Now, I had my Perdix and Oceanic Atom 3.0 with me so it knew I was nowhere near going into deco.
 
The more I think about it, I think calculating SAC is meaningless. Aren't you comparing air consumption during some sort of activity on the surface with the activity at whatever pressure you are diving to and trying to come up with how much dive time you have left? If so it sounds like apples and oranges to me. Convince me otherwise.
That is not what SAC is.

SAC is surface air consumption. It is your actual air consumption but normalised to the depth you are/were at, either currently, or average depth for the whole dive.

There are two ways you can use SAC. One is to calculate your SAC after your dive (either manually or with dive software) and you can use this to compare your air consumption between dives. The other is what many AI dive computers do where it calculates your SAC during the dive (based on your air consumption and average depth over the last n minutes) and can display the SAC plus estimate your air time remaining - much like modern cars predict how far you can go before your fuel tank is empty.

If you dive metric, SAC is very easy to calculate after a dive. All you need is starting pressure, ending pressure, dive duration and average depth (in metres):
SAC = ((starting pressure - ending pressure)/duration)/((average depth/10)+1)

An easy example. 100 minute dive with an average depth of 10m with starting pressure of 230 bar and ending pressure of 30 bar.
200 bar was consumed during the dive so air consumption was 2.0 bar/min. But as you were at an average of 10m where the pressure is doubled, SAC was 1.0 bar/min.

For non metric it is:
SAC = ((starting pressure - ending pressure)/duration)/((average depth/33)+1)
where average depth is in feet.

If you always dive with the same sized tank you can directly compare the SAC from one dive to the next. Different sizes tanks make it not so good and you are better off using RMV (respiratory minute volume) which takes the tank size into consideration.

On a dive, an AI dive computer does exactly the same calculation but only over the last n minutes, where n could 1 to 5, It tells you how you are currently doing in terms of air consumption but it can also calculate how long your remaining air will last assuming you keep the same air consumption and stay at the same depth.

But my Oceanic dive computers and my Perdix do this. I find the Oceanic very accurate for the whole dive. The Perdix seems a bit conservative at the start of the dive but gets more accurate towards the end of the dive.
 
I have one app on my phone (i messed around with the subsurface app but I don't find a use for it on my phone, just on my pc).
It has all my run/dive/hike/bike data on it.
If I wanted to, I could switch from Simrad to Garmin on my boats and have all that data there too.
The Garmin Connect app is not that great for displaying dive data. This is my dive from yesterday:
GarminConnectUnknownActivity.jpe
 
The Mk2 is reported to have DEM calibration, which potentially will provide more accurate altitude readout, depending on how the feature is implemented.This is a big deal for me. But not big enough.

The Mk2 also has "magnetic buttons" which suggests a sealed case without dynamic o-rings. Also a big feature, but again not ... .
I wonder how the updated altimeter will function then

I manually set mine while on a boat and did the auto calibrate on the mk1 and both times the altitude went above and below sea level.

Yeah the inductive buttons are interesting but not something that pushes me over the edge.
 

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