Ratio Dive Computers Announces New iX3M 2!! Our Best Dive Computer yet!

[stiebs]

Any hand on experiences on the gen 2?

I just came back from a week of rec diving using my iXM2 Pro. Had used it on two shallow shore dives before the trip. and then 2 dives per day for 5 days.

Most dives between 20m and 30m, with one to 40m, and all dives around 50-70 mins duration. Overall very happy with it.

I started the trip with both it and the transmitter charged to 100%. I only had the iX3M 2 plugged into USB to download my dives each evening, and that kept the charge above 90% for the trip. I never recharged the transmitter, and the startup light sequence still shows the battery at >50%.

I had the iX3M 2 set to "P2", and my Garmin Descent Mk2i set to GF 80/80 to match.

On algorithms, they ran very close, as expected, with a couple of slight differences, especially when I exceeded NDLs. As expected, both tracked very close to NDL, but on a couple of dives after I triggered a small deco obligation, the Garmin washed it off pretty quickly during ascent. The Ratio also washed it off, but at a slightly slower rate.

On 3 of the 10 dives I exceeded NDL, but deco obligation was washed off by the time I had ascended to around 10-12m. The Garmin still asked for a safety stop, but the Ratio only started a safety stop time if I did not exceed NDL at all. This is possibly due to the "DECO CTRL" setting, which is worded very poorly with a triple negative in the manual:

So DO NOT deactivate the DECO CTRL if you don’t want to carry out the Safety Stop.

The display is excellent, and the buttons very easy to use. I like the way that the screen shows what the buttons are, without having to memorise what each button does in which context. Although not all screens have it - not sure if that's an omission or by design.

I love my Garmin Descent, but my eyes love the Ratio.

I had a couple of queries that I sent to Ratio support, and I found them very engaging and helpful.

 

[roge]

I just came back from a week of rec diving using my iXM2 Pro. Had used it on two shallow shore dives before the trip. and then 2 dives per day for 5 days.

Most dives between 20m and 30m, with one to 40m, and all dives around 50-70 mins duration. Overall very happy with it.

I started the trip with both it and the transmitter charged to 100%. I only had the iX3M 2 plugged into USB to download my dives each evening, and that kept the charge above 90% for the trip. I never recharged the transmitter, and the startup light sequence still shows the battery at >50%.

I had the iX3M 2 set to "P2", and my Garmin Descent Mk2i set to GF 80/80 to match.

On algorithms, they ran very close, as expected, with a couple of slight differences, especially when I exceeded NDLs. As expected, both tracked very close to NDL, but on a couple of dives after I triggered a small deco obligation, the Garmin washed it off pretty quickly during ascent. The Ratio also washed it off, but at a slightly slower rate.

On 3 of the 10 dives I exceeded NDL, but deco obligation was washed off by the time I had ascended to around 10-12m. The Garmin still asked for a safety stop, but the Ratio only started a safety stop time if I did not exceed NDL at all. This is possibly due to the "DECO CTRL" setting, which is worded very poorly with a triple negative in the manual:



The display is excellent, and the buttons very easy to use. I like the way that the screen shows what the buttons are, without having to memorise what each button does in which context. Although not all screens have it - not sure if that's an omission or by design.

I love my Garmin Descent, but my eyes love the Ratio.

I had a couple of queries that I sent to Ratio support, and I found them very engaging and helpful.

much appreciated. This is very helpful!

 

[scubadada]

Hi @stiebs

Do you have any examples of the differences you observed between the two computers set at 80/80? For instance what was the largest discrepancy you observed in NDLs. I would imagine they went into deco at slightly different times and that there were no major differences in your short deco obligations, right? Did they behave about the same on both 1st dive and 2nd each day?

Thanks

 

[stepfen]

Hi @stiebs

Do you have any examples of the differences you observed between the two computers set at 80/80? For instance what was the largest discrepancy you observed in NDLs. I would imagine they went into deco at slightly different times and that there were no major differences in your short deco obligations, right? Did they behave about the same on both 1st dive and 2nd each day?

Thanks

I dive an iXM2 and a Peregrine. Both set to GFHi 75 or so (I can't remember right now GFLo - I don't do long deco dives anyway). Peregrine usually has about double the NDL of the Ratio!!! Interestingly as NDL gets close to 0 the difference between the DCs decreases and near NDL the difference if any is small (1-2 mins).
If interested I can send you subsurface dives showing this.

 

[scubadada]

Hi @stepfen

Do you have the Ratio Pro, Deep, or Tech model? The Pro and Deep only have Buhlmann presets, no custom GF; 93/93, 90/90, 80/80, 75/75, 50/85, and 45/80. The Tech has custom GF settings. Of course, the Peregrine has the 3 Shearwater presets; 45/95, 40/85, 35/75, and custom GF.

If you have the GF high set the same for both computers, seems like the NDLs should run very similarly. The GF low should only give you deeper 1st stop for longer decompression

 

[stiebs]

Hi @stiebs

Do you have any examples of the differences you observed between the two computers set at 80/80? For instance what was the largest discrepancy you observed in NDLs. I would imagine they went into deco at slightly different times and that there were no major differences in your short deco obligations, right? Did they behave about the same on both 1st dive and 2nd each day?

Thanks

I can't recall the exact differences during the dives, but here's one dive profile from Subsurface for both the Garmin and the Ratio. The Ratio is set to P2, which according to the manual is 80/80. The Garmin is set to 80/80, and as you can see from the screenshots, Subsurface is set to 80/80.

The first profile is the Garmin, showing a 3m deco that cleared at the 29 min mark. Deco started at 18:20
The second profile is the Ratio, showing a 3m deco that cleared at the 34 min mark. Deco started at 18:10
The last screen grab is the Subsurface calculated 3m deco that cleared at 32 minutes. Deco started at 18:10

The subsurface calculated deco shows almost exactly the same for both the Garmin and the Ratio log profile.

The Garmin logs depth every 1 second and the Ratio every 10 seconds, but even if the algorithm calculations occur at a similar difference in frequency I wouldn't have thought that would result in such a large difference. (You'll also notice that the Garmin continues logging to the surface, whereas the Ratio stops logging at 1.5m)

In this dive, the difference is academic as I never got close to my deco ceiling, but I'll need to do a couple of long bottom time dives on twins to see how they compare in a "real" deco scenario. Certainly interesting the differing results from two computers that are in theory running the same algorithm.

 

[BoltSnap]

The Garmin logs depth every 1 second and the Ratio every 10 seconds,

"Logs" is different from measuring. I think that the Ratio measures depth more frequently for deco calculations but records/logs it every 10 seconds.

I'll contact Ratio to clarify.

 

[stepfen]

Hi @stepfen

Do you have the Ratio Pro, Deep, or Tech model? The Pro and Deep only have Buhlmann presets, no custom GF; 93/93, 90/90, 80/80, 75/75, 50/85, and 45/80. The Tech has custom GF settings. Of course, the Peregrine has the 3 Shearwater presets; 45/95, 40/85, 35/75, and custom GF.

If you have the GF high set the same for both computers, seems like the NDLs should run very similarly. The GF low should only give you deeper 1st stop for longer decompression

I have the Pro model (no custom GFs) and I have it at 75/75. My Peregrine is set to 50/75.

See my latest dive (also attached subsurface file), say @20mins Ratio gives an NDL of 15 mins

while my Peregrine 32minutes which closesly matches with Subsurface's calc value (30 mins):

Notice though that both DCs enter (a similar) deco almost simultaneously.

FYI both DCs were set for the same O2 (31% for this dive), Ratio was on my right hand, Peregrine on my left, and surface interval before the said dive was about a week (so no unrecorded residual nitrogen).

One difference I see is that Peregrine is set for 3m (10ft) Deco while Ratio is set for 6m (20ft) but that's irrelevant to the NDL times.

I know that no 2 DCs are the same (depth/pressure sensor differences, differences in algorithm's implementations, sampling rates/times etc etc etc) and I am not complaining. I just find it interesting that DCs with the "same" algorithm get substantially different NDLs.

 

[Tschens]

Can anyone say if the Divelog App (‎Dive Log) is compatible with this computer (direct download of dives with bluetooth)? The app only mentions various "iX2M 2021 GPS" versions of this computer to be compatible. However, the GPS versions can only be bought by the militrary.

 

[drakcheslav]

I know that Subsurface mobile works with bluetooth connection, which I'm guessing that this model is in the libdive library. So i think it should work