DCIEM Decompression Model

[JeffMandell]

The new dive computer from Citizen uses something called the DCIEM Decompression Model.
Is anyone familiar with it and if so, does it seem like a wise choice? Is it comparable to any of the other major computers on the market?
Thanks.

 

[Charlie99]

It was developed by the Canadian government. Unfortunately, the tables are copyrighted and not usually available on the web. The Fleet Diving Unit, Atlantic had it posted for a while. PM me if interested.

It differs from other dissolved gas models (PADI/DSAT, Buehlmann, USN/NOAA, etc) in that it assumes that the different time constant tissues are in series with each other, not in parallel. The tables also differ in that the repetitive dive tables generate a multiplying fudge factor --- you multiply the actual dive time by the fudge factor to get the equivalent dive time (Most other tables have you add a residual nitrogen correction factor.

The DCIEM sports diving table has fairly conservative initial NDLs. 25 min at 80' and 50 minutes at 60' for example. 1 hour after the 80' 25 minute dive, the NDLs for the second dive will be 66% of the initial NDLs. 1 hour after a 60' 50 minute dive, repetitive NDLs are 62.5% of the initial NDLs.

I wouldn't hesitate to use a computer based on this model.

 

[Karl_in_Calif]

I used the DCIEM air tables during my stage decompression course. I found them to be fairly conservative, and I was one of the last people out of the water with them.

If you use computer software for deco planning, you can usually set your own gas tension levels, such as 20% deep and 80% shallow, which is a fairly conservative setting. Or you can use a more aggressive approach that will get you out of the water faster, like 20% deep and 90% shallow.

With DCIEM there is a fixed, fairly conservative convention that roughly approximates 20/80. Therefore if you are using it for NDL air diving, you should be fairly safe with it.

If you are doing actual deco dives, you would be better off with dive planning software like Abyss or DecoPlanner, however. Then you can key in your preferred tolerances and your multiple gasses.

I dont know if your dive computer has nitrox settings. I hope so. EAN36 is a fairly good gas for diving shallower than 100 ft. and for repetitive diving. I only mention that because I would be more concerned that a dive computer be nitrox compatible rather than worry that the algorithm such as DCIEM is conservative and safe.

EAN36 is conservative and safe.

 

[Genesis]

dives his Cyber Aqualand into deco (intentionally) and has yet to bend himself doing so. From the profiles it generates it appears to be QUITE conservative in terms of the stops it demands.

 

[JeffMandell]

Genesis once bubbled...
dives his Cyber Aqualand into deco (intentionally) and has yet to bend himself doing so. From the profiles it generates it appears to be QUITE conservative in terms of the stops it demands.

Does he like the unit despite it being so conservative? Do you think it's more conservative than the Suuntos?

(Also, thanks to Charlie for a very useful answer.)

 

[Genesis]

He loves the thing.

I have to admit - I think its pretty cool. I'd rate its conservatism as roughly equal to the Suunto on the NDL side, and a bit MORE conservative in deco.

He has the air version - the NX is too new, although he said that they will flash it for him - he just hasn't figured out if he wants to dive Nitrox often enough yet to have it done.

I've seen the NX versions on eBAY in the upper 300s, brand new, which is a killer deal given that the "list price" is $850!

He has the download cradle as well, but I don't know if that's really necessary, since I understand that it can do IrDA if you have the port on your PC and software (but I don't know if you can get the software from them without buying the cradle or not.)

IMHO one of the best features of the computer is that you NEVER have to open it, since its battery is recharged when its in its cradle. As such the entire 'oh god, will it flood" thing goes away.

 

[Karl_in_Calif]

Genesis once bubbled...
He loves the thing.

Are these nitrox compatible? Or do you have to follow an air algorithm even though you are diving with EANx?

 

[JeffMandell]

It's hard to believe the newest version is selling on ebay for that little. I found a web site with it selling at 50% off (!!), but $300 has to be below dealer cost and as it's a new item, there can't be excess inventory that's got to go. I"m guessing you're seeing the previous version.
Anyway, pretty tempting at $425.

p.s. Yes, nitrox capable.

Here's the Citizen link for the product. From here you can download the PDF brochure that spells it all out.

http://www.citizenwatch.com/us/technical/aqualand/cyber_aqualand_nx.html

 

[Genesis]

on eBAY for the ones there is from $399 to $550.

These are definitely advertised as the "NX" versions.

My friend's is an air computer, but he dives air - so it doesn't matter to him. He apparently contacted Citizen and was told that the firmware was flashable, but it cannot be done in the field - he has to send it in to them to have it flashed to the "NX" version.

He hasn't done it yet, as he basically always dives air and as such the cost is not worth it to him.

 

[rdriver]

Could someone please tell me if this available in an imperial version or is it just metric?
Rob