Can Suunto Cobra 2 be used for deco diving?

[NudeDiver]

Or it may be that Dive Rite and Suunto have different lawyers writing their disclaimers, Suunto being the more conservative company.

There you go. Suunto's lawyers use a more conservative algorithm

 

[MXGratefulDiver]

I think just about everyone that does intentional deco dives is saying (not implying) that recreational dive computers are not the way to do the job. It is far better to have a written deco plan and then make the dive using 2 computers in gauge mode.

Not necessarily. There are several computers on the market that are completely appropriate for doing staged decompression diving. The Cobra isn't one of them. It's designed for recreational diving. The Internet isn't the appropriate place to be learning why that is ... if you want to do that type of diving, some training would be a better use of your finances than a computer.

There are a very few computers that are intended to be used for deco diving. They have neat things like electronic games, eBook readers and other amusements to occupy your time while you hang for long periods of time. The VR3 has these features. I don't think the LiquiVision does but you can spend a lot of time admiring the display.

There are far more important features to look for in a tech dive computer than games. Perhaps the most important would be a decompression algorithm that's designed for staged decompression diving ... rather than one that's been modified for recreational use. There are other features provided by different model computers ... some are more useful for staged decompression diving than others, depending on how you're using the computer to plan and execute dives (not just the one you're doing, but how you're going to look at planning future dives).

But when the user manual clearly says that the computer is not intended for deco diving (see post #40) and that the diver should ascend immediately when the dive computer shows a requirement for a deco stop it is a pretty good indication that the computer is not intended for deco diving.

The problem with "ascend immediately" is that the computer doesn't provide any useful ceiling information. Most will tell you not to go shallower than 10 feet until you've cleared your deco obligation. The problem with that is most people using these computers do not understand decompression, and ... following the instructions ... will ascend directly to 10 feet. Depending on the depth profile and amount of obligation you've incurred, this could be a recipe for a Type II hit that'll put you in a chamber, and ... if you happen to get really unlucky ... in a wheelchair for the rest of your life.

But, again, it's up to the end user. If they read the manual and understand the capabilities and then insist on doing something that the computer wasn't designed for, well, that's their choice.

Richard

I write manuals for a living, and understand something fundamental about them ... which is that most people won't actually read them. At best, manuals are most commonly used to find a specific piece of information. The vast majority of the people reading this thread, in fact, probably have never opened the manual that came with their dive computer. Most likely got their computer and started pressing buttons to "figure out" how it works. Once they've got the basics down they take it diving. Many (one I've even dived with) do not understand what the computer means when it starts flashing that little "10".

Or it may be that Dive Rite and Suunto have different lawyers writing their disclaimers, Suunto being the more conservative company.

Adam

... and if you get bent riding that computer and doing what you "think" it's telling you, I'd be willing to bet you'd be quick to hire a lawyer of your own and try blaming it on the company that made the device, as well as the vendor that sold it to you.

... Bob (Grateful Diver)

 

[pt40fathoms]

You know Bob, sometimes people simply want to believe what is convenient for themselves and the situation they wish to put themselves in. It seems that NudeDiver has focused on my warning that if you plan to dive into deco on a repetative basis with the Cobra 2, you will most likely take a chamber ride. Apparently he does not like this, possibly because it touches too close to home? I don't know.

But I agree with your sentiment here. Do what you want and don't bother to ask questions if you don't intend on taking advice, rather you wish to seek confirmation to proceed. Which as all know, confirmation to continue to do questionable activities that may hurt you is VERY easy to get on the internet.

pitty...

Believe what you want ... dive recreational gear to 300 feet for all I care.

Good luck ...

... Bob (Grateful Diver)

 

[NudeDiver]

It seems that NudeDiver has focused on my warning that if you plan to dive into deco on a repetative basis with the Cobra 2, you will most likely take a chamber ride.

Oh, good grief. I focused on one particular statement of yours:

If you do dive the computer and go into deco several times during the course of a dive weekend or trip, you will almost certainly enjoy a ride in a chamber.

because it is simply incorrect. And by the way, we still haven't seen any evidence supporting your assertion.

Apparently he does not like this, possibly because it touches too close to home?

Now there's a wild assumption.

I don't know.

I agree.

 

[MXGratefulDiver]

This thread's an excellent example of why so many experienced divers who used to offer valuable information on ScubaBoard don't bother posting here anymore ... they got tired of being "corrected" by 50-dive experts and folks who were DM's for, like, hours before becoming Master Scuba Diver Trainers ...

Some folks are just better off learning the hard way ...

... Bob (Grateful Diver)

 

[NudeDiver]

Yeah - nothing like being able to lay down the law like a king, and expecting the sycophants to just heed it without any thought or question whatsoever - let alone have them collect information, analyze it and discuss it with others. I can see how that would put a lot of people off.

 

[MXGratefulDiver]

Yeah - nothing like being able to lay down the law like a king, and expecting the sycophants to just heed it without any thought or question whatsoever - let alone have them collect information, analyze it and discuss it with others. I can see how that would put a lot of people off.

I'm honestly not looking for an argument ... nor trying to "lay down the law". But from the context of your comments, and those of a couple other people who have participated in this conversation, I would seriously doubt you've ever actually done any decompression diving. And if you have, I'd be seriously worried about your safety.

If you don't understand the topic, you shouldn't be handing out advice. And for sure you shouldn't be trying to pick arguments with the people who do.

You simply can't learn this stuff on the Internet. Try getting some training, and doing some dives ... THEN come back and read your own comments. I suspect you'd see them in a very different perspective.

... Bob (Grateful Diver)

 

[NudeDiver]

I'm honestly not looking for an argument ... nor trying to "lay down the law". But from the context of your comments, and those of a couple other people who have participated in this conversation, I would seriously doubt you've ever actually done any decompression diving. And if you have, I'd be seriously worried about your safety.

According to one poster, all diving is deco diving But within the intent of your comment, no, I haven't.

If you don't understand the topic, you shouldn't be handing out advice. And for sure you shouldn't be trying to pick arguments with the people who do.

I understand the topic. And I never said that the Cobra is designed for deco diving. However, I did take exception with the one poster's comment, which said that if you are using a Cobra, and it goes into deco mode several times over the course of a weekend or trip, that you are "almost certainly going to a chamber", because that's just not true - and no supporting evidence, let alone proof, as provided to support this statement. Do you really think that's true? Really?

FWIW, NWGD, I do respect your opinion (as well as the opinion of some of the other people on here). If I didn't, I'd just add you to an IgnoreList However, that doesn't mean I will not ask probative questions and ask you to defend your opinion - if nothing else, so I can understand where it comes from. It's also the nature of learning

Cheers!
nd

 

[MXGratefulDiver]

According to one poster, all diving is deco diving But within the intent of your comment, no, I haven't.

I understand the topic. And I never said that the Cobra is designed for deco diving. However, I did take exception with the one poster's comment, which said that if you are using a Cobra, and it goes into deco mode several times over the course of a weekend or trip, that you are "almost certainly going to a chamber", because that's just not true - and no supporting evidence, let alone proof, as provided to support this statement. Do you really think that's true? Really?

There is no "true" in decompression diving ... no line on which you can stay on the "safe" side, nor cross onto the "unsafe" side. There are simply too many unknowns and too many variables. So you can only really talk about it in terms of probabilities. And some of the biggest risk factors are going to depend on your particular physiology ... because how your body responds to decompression is going to vary from person to person, day to day, dive to dive. That's why there is no simple, straightforward answer to your question. And it's also why I said if you want to do these dives, get some training ... because no computer will keep you "safe" if you use it in a manner it wasn't designed to be used. It's got nothing to do with lawyers, and everything to do with physiology.

Certainly, there's a difference between accidentally exceeding NDL's by a couple minutes and doing a planned, staged decompression dive. But there are some similarities in principle as well. The deeper you go and the longer you stay down, the more your body accumulates dissolved gas ... which then will come out as you ascend. How it comes out will depend on a number of factors ... not least of which is how quickly you ascend, the type of gas you're breathing, and the manner in which you ascend (making stops at various points) along the way. And still you're playing with probabilities and unknowns. It helps to understand the basics of the various decompression models that are used to design computer algorithms ... but even then you'd have to simplify things almost beyond the point of usefulness to make it understandable in an internet discussion.

It's better for a recreational level diver to simply understand that when they push NDL's, they're playing with fire. And if you haven't yet learned how to handle the fire safely, you're likely going to end up burning yourself. In this respect ... and although I wouldn't have put it exactly the way he did ... yes, I can see where pt40fathoms is coming from ... someone who pushes NDL's multiple times over the course of a couple of days is asking for problems. I wouldn't use the term "almost certainly" ... because where decompression is concerned, nothing is almost certain. You can break every rule in the book and get away with it one day, and go out the next ... do everything "right" ... and end up in a chamber. It's all a matter of playing the probabilities.

Every dive is situational ... and our very best "defense" against injury is going into that dive with a reasonable understanding of the risks involved. That way we can be prepared to deal with those risks in a reasonable manner, make decisions about our dive plan based on knowledge, and if something happens that causes us to have to change the plan (like accidentally exceeding NDL) we can make informed decisions on what to do about it.

Riding a recreational computer on a deco dive is a really bad idea. First and foremost because, as I previously said, it's the wrong tool for that job ... but more importantly, because someone who truly understood the hazards of decompression wouldn't have to ask, nor be told, that it's a bad idea.

If you're going to do decompression diving, get a tool that's designed for that type of diving. Better yet, get training first ... because there's a huge difference between how a Nitek He, an EMC-20H, a VR3, and an X1 work ... and the one you decide on will be determined a great deal on how you decide to plan and execute your dives.

All of diving is a crap shoot. Recreational diving is relatively safe because it has so many layers of conservatism built into it ... that's not because of lawyers, it's because of probabilities. Once you exceed NDL's, you're peeling those layers of conservatism away and leaving yourself more open to risk. Your recreational computer was never designed to consider or mitigate that risk.

That's why it's not such a good idea.

FWIW, NWGD, I do respect your opinion (as well as the opinion of some of the other people on here). If I didn't, I'd just add you to an IgnoreList However, that doesn't mean I will not ask probative questions and ask you to defend your opinion - if nothing else, so I can understand where it comes from. It's also the nature of learning

Cheers!
nd

I've never had a problem with people asking questions ... or even questioning things I say. As an instructor, my favorite question begins with the word "Why".

It's the reason for all those articles on my website ... I wrote them for the developing diver who wants to understand more about topics that don't get covered so much in class. If you haven't done so, read the ones on deco and deep diving ... they might help you better understand what I and a couple others have been trying to explain.

... Bob (Grateful Diver)

 

[Hatul]

According to one poster, all diving is deco diving But within the intent of your comment, no, I haven't.

I understand the topic. And I never said that the Cobra is designed for deco diving. However, I did take exception with the one poster's comment, which said that if you are using a Cobra, and it goes into deco mode several times over the course of a weekend or trip, that you are "almost certainly going to a chamber", because that's just not true - and no supporting evidence, let alone proof, as provided to support this statement. Do you really think that's true? Really?

It's ironic that Suunto has been singled out in this thread. The Suunto algorithms are known to be one of the most conservative, and much more so than Navy tables. While I have not used my Vyper for decompression diving, my guess is that the problem with using it so is just the opposite. Instead of ending up in a recompression chamber, you get penalized and end up with no bottom time.

One of the dive guides in Cozumel sold his Vyper for exactly this reason. The computer did not allow him sufficient dive time.

Adam