Nitrox and computers

[frndrfoe]

Hi,
I am new to nitrox and have only had the class so far. I am looking at computers and trying to decide how important multi gas abilities are for recreation only diving. I would expect to go out on dives with the same gas for every dive but sometimes bad things can happen and that's the only time I would change gas.

I am wondering if thinking about getting stuck with air or a different mix on a second dive due to tanks getting mixed up or left behind is enough of a concern to base a computer purchase on if I only expect it to occur by something beyond my control. I know that each person is resposible for their own equipment but **** happens.

I am looking at that new Deepblu computer and it states

"Multi-Gas: COSMIQ does not offer a multi-gas function. Only one type of gas may be set (oxy-
gen 21%-40%). If you are planning a multi-gas dive, DO NOT use COSMIQ as your primary
device."

I might be over thinking possibilities and should plan to just do math or skip a second dive if I'm in such a situation.

Thanks for your input

 

[MaxBottomtime]

Multi-gas computers are for using more than one gas during the same dive. You should look at Nitrox computers.

 

[Fogest]

Nitrox is not multi gas. That is tech diving kinds of things they are talking about with gas mixes. What you quoted there sounds fine. It can do up to 40% oxygen in your nitrox mix. It can be changed between dives no problem. By multi gas they are not talking about using various nitrox mixes in a day.

 

[frndrfoe]

Ohh, I misinterpreted that. I thought changing your mix between dive 1 and dive 2 would mess up your computers algorithm or just not be a changeable parameter. Obviously my first dive computer purchase

 

[tbone1004]

so, my opinion on this matter is being forced out of the black and white rule that I had because this COSMIQ is what it is, but I disagree with the comments above 100% and will explain why. Disclaimer, I am a COSMIQ ambassador and my computer will be arriving shortly and am very excited about it.


Normally I only advocate for divers to purchase computers with at least two gas capability, that have algorithms programmed for decompression. That was based on the fact that you could purchase something like the DG03 for $250, or the Nitek Q for $400 both of which could do that and were not any more expensive than the junk recreational computers like the Zoop which is a truly useless computer imo. Reasons being that it is easier to change from gas 1 to gas 2 if you have two tanks that are different nitrox mixes and you want to maximize bottom time. I.e. you have a 30% and a 32% tank, doing two dives with the same profile, so dive 1 is on 30, and dive 2 is on 32. It is easier to make a gas switch on the boat than it is to have to reprogram your computer. The other scenario is if you are in the water and your buddy is on a mix significantly lower than yours, i.e. you are on 32% and he is on air. You want to switch over to air on your computer so it calculates your decompression schedule accordingly, whether that is NDL's and it isn't giving you too much time on your second dive, or if you are pushing NDL's on nitrox, you don't get bent by violating NDL's. The comments above are true in the fact that normally when we talk about multi gas computers it is with the intent of using a different gas for decompression, or stage diving, or whatever, but there are benefits to having at least a 2 gas computer for recreational diving. They also don't become paper weights or relegated to gauge mode with tables if you do actually get into light decompression diving.

Now, this COSMIQ comes out at $300. It currently has a fixed deco algorithm, but it is at least buhlmann and they will be coming out with conservatism options in the next firmware upgrade, but it is one gas for recreational diving. The nice thing with this is they allowed the app to program the gas mix and set alarms, but you can also set the mix from the computer in the same fashion as any other computers mix changing. You cycle through the options until you get to the mix you want. Included in the $300 is a free diving and gauge mode, something the normal recreational computers don't offer, and most importantly dive log uploads. There are some minor quirks in terms of how they handle deco if you go into it that I am hoping they fix in a firmware upgrade, but as of right now I think for a recreational only computer, it is the logical choice on the market, especially when up against computers like the Zoop

 

[frndrfoe]

Thanks guys, I have already learned from this thread and that's awesome.

 

[stuartv]

Normally I only advocate for divers to purchase computers with at least two gas capability

I agree with tbone that being only one gas is a non-issue for the Cosmiq. I further think it's a non-issue for any Rec computer. Sport (aka Recreational) diving is implicitly a "one gas" affair. The training for all sport diving is for only using one gas. If you are using more than one gas during an individual dive, you are no longer doing "recreational" diving. You have strayed over into "technical diving". My Rec computer supports 3 gases. And I normally use a different mix on every dive, compared to whatever my previous dive was. Whether it's 28% on one dive and 30% on the next or 30% on one dive and Air on the next or whatever. Despite this fact, I have always just programmed Gas 1 on my computer before each dive. At least on the Oceanic, Shearwater, and SeaBear computers I have used, changing the FO2 on Gas 1 is so quick and easy that I've had no motivation to set up 2 different gases and just switch between them.

Also a non-issue because I would guess that most people buying their first computer are going to be using the same gas on all dives in the same day anyway. If you're going out on a charter boat and renting tanks, they're almost certainly going to give you the same gas in both tanks.

OTOH, I would be a tiny bit reluctant to buy a Cosmiq yet.

- They obviously don't have it TOTALLY together yet as they don't have an adjustable conservatism factor built in yet and their website says they will have one in a future firmware upgrade.

- Their algorithm is proprietary, which means nobody outside their company knows how it really performs. The manual doesn't even give an NDL chart (like, for example, my Oceanic computer's manual does). So, there is no data to know how conservative or liberal their proprietary algorithm actually is.

- The FAQ on their website says this:

You MUST download and install the Deepblu app in order for COSMIQ to operate properly. Only a limited number of settings can be changed manually using COSMIQ so it is imperative that you download the Deepblu app to properly adjust your settings.

A REQUIREMENT to use a separate app to access all functions/options of the computer is a big No for me.

- The spec'ed battery life is 6 to 7 hours. That is short. My SeaBear is spec'ed at 15 hours and I end up charging it every 2 to 3 days (in a row) of diving. That is about the shortest battery life I'd be willing to deal with. If I forget to charge it one night (when I intended to), I can still get through another day of diving. With a shorter life, I'd be worried about forgetting to charge it one night and having no margin. I.e. not lasting through a whole day the next day.

- I love the air integration in my Oceanic computer. I would at least want that option. Their FAQ makes it pretty clear they won't have that option for the Cosmiq. In that case, if I didn't get one that would support AI, I would instead get the least expensive computer that would work for me. In your case, the Puck Pro will do everything you need, for less money.

The Cosmiq looks pretty cool. But, even if I did not care about AI, I think I would want to see a fair bit of real world usage reports, at least, before I bought one. Real world results from the algorithm could prove to be too liberal OR too conservative. Real world battery life could be annoying (or worse) short. Being required to use a smartphone app does not work for me, either (though I am a huge gadget nerd and smartphone user).

 

[Patoux01]

Now, this COSMIQ comes out at $300. It currently has a fixed deco algorithm, but it is at least buhlmann and they will be coming out with conservatism options in the next firmware upgrade, but it is one gas for recreational diving. The nice thing with this is they allowed the app to program the gas mix and set alarms, but you can also set the mix from the computer in the same fashion as any other computers mix changing. You cycle through the options until you get to the mix you want. Included in the $300 is a free diving and gauge mode, something the normal recreational computers don't offer, and most importantly dive log uploads. There are some minor quirks in terms of how they handle deco if you go into it that I am hoping they fix in a firmware upgrade, but as of right now I think for a recreational only computer, it is the logical choice on the market, especially when up against computers like the Zoop

Well, the zoop novo does gauge / freediving as well.

As for taking a phone app, sure, very smart. Do people in your areas really take their smartphones out on a dive boat? I mean, the dive boats I've been on, there's absolutely no way I'd take my phone out. (and there's also not gonna be an app for my phone anyway)

 

[tbone1004]

the new zoop novo does, but at $330 why would you spend 10% more for a computer that does less?

You can control important stuff from the computer, gas mix and mode. You can't set the limits in terms of depth or time without the app, but you aren't doing that from the boat anyway, and if you can't be trusted not to violate those parameters, you shouldn't be diving in the first place

 

[Patoux01]

Well, if it's something you:
- don't need
- can't set (my case)

Why on earth is it a benefit?