Would you really know what was going on if your computer went into Deco...?

[BradJ]

Why do the Suuntos want to send you up to ten feet to decompress?
Aren't they using a bubble model that wants deeper stops?
The users manual is vary vague on decompression procedures, saying only that the ceiling may vary depending on the profile.
My experience and from discussions here, it seems assumed that the Suuntos will always send you up shallow to stop.

 

[Genesis]

Why do the Suuntos want to send you up to ten feet to decompress?
Aren't they using a bubble model that wants deeper stops?
The users manual is vary vague on decompression procedures, saying only that the ceiling may vary depending on the profile.
My experience and from discussions here, it seems assumed that the Suuntos will always send you up shallow to stop.

Because most of the claims about "bubble models" and such that the various marketing interests make are BS, as the profiles these computers actually produce when in deco shows.

 

[Snowbear]

Why do the Suuntos want to send you up to ten feet to decompress?

Since Suunto's intent is to sell these computers as recreational, "NDL" computers, they do not build in decompression proceedures. If you "violate" the NDL of a particular dive, they attempt to keep the errant diver from getting bent by giving you a "ceiling" of 10' that you are not supposed to ascend above before the treatment has completed. Sure you can pop up to 10' and wait it out, but if you actually learn deco proceedures, plan your dive including gas needs and follow it on every dive, despite what your computer is "telling" you, you will find you are less tired afterwards and more ready to jump back in after a good SI.
When I was still using it as a computer, I found the Vyper actually will credit for deep stops, often to the point of "clearing" well before 20', depending on the profile.

 

[MikeFerrara]

Why do the Suuntos want to send you up to ten feet to decompress?
Aren't they using a bubble model that wants deeper stops?
The users manual is vary vague on decompression procedures, saying only that the ceiling may vary depending on the profile.
My experience and from discussions here, it seems assumed that the Suuntos will always send you up shallow to stop.

Most of the recreational dive computer bubble model implimentations are limited to some type of deep stop wrap around dicombobilated kind of thing that don't make much sense to me when I read the descriptions.

Most are still primarily Haldanian models which get you as shallow as they can as fast as they can. Way back when it was thought that avoiding the "M" value of the leading compartment would prevent bubbleing. We now know that to be false so we try to decompress in a way that limits bubble formation and growth. We do that by staying deeper and increasing the offgassing gradient by breathing higher FO2 gasses during decompression. As you can probably tell, another thing I won't do is a dive that requires staged decompression with back gas alone. It od course can and has been done many times and I'm prepared to do it in an emergency but why the heck would I do it on purpose?

Getting shallow quick probably suits the purposes of a recreational dive computer manufacturer just fine since they probably expect you to be low on gas also, not that I really think they gave it that much thought. Keep in mind that most of these computers are not meant for staged decompression diving and the owners manual usually warns against using them for that. Their staged decompression functions are there with the intent of guiding you to the surface after a screw up. Lots of these computers will even shut down on you for 24 hours and some will shut down on you while you're still in the water if you push them too far. The owner manual probably also suggests that you don't dive again for 12 or 24 hours or something after putting the computer into decompression.

Intentionally putting one of these things into decompression is insanity as far as I'm concerned unless you tie it to the end of a fishing line and send it in by itself. It's damage control for a mistake why would any one want to make the mistake on purpose?


When we intentionally do a staged decompression dive we do it with the goal of setting ourselves up for the next dive or the half a dozen trips up the mountain to get our gear back to the truck.


A freind of mine was bent pretty bad last year on a dive that his computer was as happy as could be with. He even added some time to what the computer said he needed to do. On looking over his profile though I saw that it wasn't a dive that I would have made. He went through like 6 chamber treatments and was in the hospital for like a week. Then he spent a few weeks using a walker before switching to a cane that he was on for several months. He went and took a class after that.

If you want to dive beyond the "no-stop" limits just go learn how and have at it. Doing it following one of these vacation dive guids in a box isn't the way IMO though.

 

[jonnythan]

To totally hijack the thread, why don't the computer manufacturers start to use updated algorithms? Reading this board, they use seriously outdated data and algorithms... why don't they use something newer?

 

[plsdiver4377]

Some of them are. The one that I am familiar with, the Mares RGBM M1 does at least incorporate deep stops along with the RGBM overlay (I presume) in this version. I don't know if Suuntos' RGBM models use the deep stops or not.

To totally hijack the thread, why don't the computer manufacturers start to use updated algorithms? Reading this board, they use seriously outdated data and algorithms... why don't they use something newer?

 

[IndigoBlue]

Anyway, where was I...?

Given these two possibilities:

(1) Wear a computer, and when someday - for whatever reasons, when it goes into Deco, try to remember what all the numbers and symbles mean, and do the best thing; or​

(2) With very good & calm diving conditions, with a buddy who has done this before and 1,000 lbs of air left to play with, surrounded by good support and even a hospital 1/2 mile away, stay down long enough to develope 2 or 3 minutes of Deco obligation, then do the Deco stops indicated.​

I think the latter has a lot of appeal, but - I don't think I could get an Instructor to help with it, becuase of the liabilities.

Comments on that one....?

Thanks, don

Do neither.

Always remember NOT to push your NDL limits, whether on an initial dive or on subsequent repetitive dives. If you did not learn this principle, then your OW1 instructor went too fast in the class.

And you are right about an instructor being prevented by insurance requirements and course standards from giving you a quickie deco lesson. The lesson on deco is to say well clear of deco, unless you actually take a staged deco course. The courses are not hard to find or take. IANTD, TDI, and NAUI all offer them, subject to prerequisites. And GUE offers a revamping of your dive methodology and re-gear-ing also, if you want the GUE version of staged deco, although I would not characterize GUE's package as "easy."

 

[IndigoBlue]

Since Suunto's intent is to sell these computers as recreational, "NDL" computers, they do not build in decompression proceedures. If you "violate" the NDL of a particular dive, they attempt to keep the errant diver from getting bent by giving you a "ceiling" of 10' that you are not supposed to ascend above before the treatment has completed. Sure you can pop up to 10' and wait it out, but if you actually learn deco proceedures, plan your dive including gas needs and follow it on every dive, despite what your computer is "telling" you, you will find you are less tired afterwards and more ready to jump back in after a good SI.
When I was still using it as a computer, I found the Vyper actually will credit for deep stops, often to the point of "clearing" well before 20', depending on the profile.

Suunto's dive computers are actually quite good, as far as their deco algorithm, for an air or nitrox dive. I have found DCIEM deco tables for air dives to be the most conservative. If you compare Suunto's dive simulator for a deco dive on air with DCIEM, you get quite similar data.

But the whole point is to stay clear of deco whenever you are diving with a computer, rather than with preplanned slates and multiple deco gasses.

I suppose that is where non-tech divers get confused, when they see that their dive computer is set up to handle deco, but there is no way to communicate to the divers the dangers of deco, unless they take a deco class.

 

[diverbrian]

However, their website didn't even mention it until recently. This is the reason that they use an "ASC time" and ceiling instead of flat out recommending where you stop and for how long is to allow divers with different ideas of decompression theory to use the same model of computer. On staged dives, I don't use the computer as much as I keep it with me so that the next dive of the day (which will likely be an multi-level, NDL dive due to the fact of gas management and that I can't get fills on the boat for my doubles) can be executed by computer which involves much less planning.

As Mike F. and Snowbear state, the manufacturer really doesn't want people using these for staged decompression diving. They aren't telling you to go to ten ft. They are telling you NOT TO GO ABOVE TEN Ft in an attempt to prevent being seriously bent. If you are diving intentional staged decompression, you should be using the profile that you are trained to use.

The take-away should still be that the only actual emergency underwater is still out of gas. If a diver finds themselves in the position of accidently having pushed their limits as has been seen a couple of times in this thread (we are human after all), the first reaction should NOT be like this----> OH MY GOD! I HAVE SCREWED UP ROYALLY AND AM ABOUT TO DIE! That equals panic which does get divers killed. Call the dive and kill off the deco obligation per the instrument that you are diving and don't go above the ceiling that it lists for any stop until it clears that ceiling.

Also, like Genesis (OMG), I like to keep my stops a little deeper for another reason. In six to eight footers, I may be on the surface a little more quickly than planned if I try to stay at ten ft. LOL

 

[Snowbear]

Suunto's dive computers are actually quite good, as far as their deco algorithm, for an air or nitrox dive. I have found DCIEM deco tables for air dives to be the most conservative. If you compare Suunto's dive simulator for a deco dive on air with DCIEM, you get quite similar data.

I suppose internally, that's true, as it credits deep stops and is considered conservative for recreational, "NDL" multilevel dives. However:

I suppose that is where non-tech divers get confused, when they see that their dive computer is set up to handle deco...

The recreational dive computer (including the Suunto) is NOT set up to handle a deco dive. The intent is to provide the errant diver with an emergency decompression "schedule" (if they have the gas reserves to complete it) when s/he screws up and exceeds the "NDL" calculated by the computer. Recreation dive tables provide for a similar contingency by extending the "safety stop" and surface intervals if the table limits were "accidentally" exceeded.