Deep Stops Recreational Divers

[CandiveOz]

I would love to see some data, but unfortunately Suunto has decided to release only sales material.

Actually you can do this. Just download the free DM5 software from Suunto and play with their dive planner. You can turn on and off deep stops and evaluate the 4 different versions of their algorithm against typical dives you do. Compare their deco profiles to your own computer. The program may be in a black box but at least you can see its results. To me that is being quite transparent.

 

[taimen]

Well I mean results from testing their algorithms in real life. Which they claim they have done with over a thousand test dives, which I don't doubt.

"Divers who properly follow the instructions of a dive computer that utilises the Suunto Technical RGBM are certain to reduce the risks of diving incidents. This is accomplished without requiring a more conservative decompression model for most dives."

 

[rjack321]

This is interesting and I have actually noticed the same.
With their latest "Suunto Fused RGBM" Suunto has actually started talking about "Wienke's Full RGBM" which is used when diving below 45 meters with trimix.
Thus they are now blending something with "full RGBM"

This isn't really a no-stop recreational profile. But anyway it looks like Suunto is still advocating something which looks like a deep stop model.

I don't like this 80m profile at all. I used to dive like that, I got tons of minor hits doing this. No thanks

 

[dmaziuk]

Harmful as in if I hang out for two minutes on my ascent like my PDIS recommends, even though I'm far from a NDL, that I could get symptoms of DCS? Is there evidence this has happened?

Best I've been able to find to date is this post:
Evolving Thoughts on Deep Decompression Stops

 

[KenGordon]

Well, let's start with the fact that using the term "RGBM" to describe something that is not RGBM would begin a lawsuit. It has been years since I saw the description of the HelO2, but IIRC, it specifically used Bruce Wienke's name in that description. What happens in it exactly? I don't know. That information is proprietary. It just seems to me that if it says the algorithm is Bruce Wienke's RGBM, it is probably a version of Bruce Wienke's RGBM.

You put yourself forward as an expert in this stuff, writing articles punished by PADI, so I expect you to be a bit less woolly than this and not just fall in with SB mythology about how different brands behave.

They, and all the similar manufacturers, have clearly employed the services of Wienke and come to some arrangement over how they market the custom fudge factors he suggests. They don't say that that Suunto RGBM is Wienke's RGBM. They do say that Suunto Fused RGBM is Wienke's RGBM, some of the time.

But, if you were to actually dive the things you would find that the fudging is simply that, they behave as a basic dissolved gas computer (eg the zoop) getting you shallow fast. Then there are ones with approximately Pyle style stops which can be enabled or not by the user, ones where they are never available and ones where they are always enabled but can be ignored in the water.

I think the logic being applied by you

...running a version of RGBM, which is inherently deep stop in its design.

and others is:

Bubble models => deep stops
RGBM => bubble model
Suunto => RGBM
hence Suunto => deep stops.

which is certainly broken in at least one place.

On the other hand, regular users of these computers find that they get stops at 6m.

Plan a 40m 20 minute air dive in DM5 for a Zoop and you get a 6m stop. On 100/100 you get a 6m stop, on 50/80 you get a 12m stop (ignoring 30s at 15). Go diving with a Perdix on one wrist and a Suunto [Technical] RGBM one on the other and see how they compare.

Concentrating on the deep stop aspects of bubbles vs dissolved gas ignores important considerations. A reasonable (at least to me and I suppose the bloke on the stage at Eurotek putting it forward) is that there are always bubbles and that re-descending lets them pass the lungs into venous the system where they are a bigger problem. That is one of the fudges talked about by the Suunto sales blurb, adding extra safety stop time for sawtooth diving.

How many times a day are you prepared to do an ascent and descent teaching CBL from depth? Is that something dissolved gas models are considering?

 

[boulderjohn]

They, and all the similar manufacturers, have clearly employed the services of Wienke and come to some arrangement over how they market the custom fudge factors he suggests. They don't say that that Suunto RGBM is Wienke's RGBM. They do say that Suunto Fused RGBM is Wienke's RGBM, some of the time.

Suunto RGBM Dive Algorithms

Bruce Wienke is quoted on the site:

DR. Bruce Wienke:
“RGBM is the most realistic model in science. The parameters are correlated with real data of thousands of dives which makes it good physics, and the data is validated and correlated. I have been working with Suunto since the 90’s and Suunto’s progression from Suunto RGBM to Technical RGBM and now to Suunto Fused™ RGBM is a very natural one. The new algorithm is a supermodel that covers all types of diving.”​

 

[boulderjohn]

You put yourself forward as an expert in this stuff, writing articles punished by PADI, so I expect you to be a bit less woolly than this and not just fall in with SB mythology about how different brands behave.

I have never put myself forward as an expert on different brands of computers. I am certainly not an expert regarding the Suunto algorithm, although I did dive a Suunto computer for the first decade of my diving life. The article I published did include a comparison of computer algorithms, and I did summarize its findings.

 

[KenGordon]

What??

It sounds like you think Suunto should be able to have their cake and eat it too, so to speak. They were presenting their computers as running "RGBM" years ago, when it was clear that no available dive computer had the computational power to actually run the model. Now that the bubble models are going out of style, you're falling back to "they never said they were running RGBM, they said Suunto RGBM." Except now it turns out that they do claim to run actual RGBM, at least sometimes.

I think they made a bad bandwagon choice from a marketing point of view, but most of the features/fudges they took into computers like the Zoop are exactly what people get warned about, avoid short SI, take care with repetitive diving and try not do go up and down too much.

Today's bandwagon is still deeper stops than a Zoop.

 

[Storker]

Just download the free DM5

When Suunto decided to go to cloud-based services as from DM4, I bailed out. I'm still running DM3 and DP3 on my PC, but there'll be pretty good skiing conditions in a certain place before I install any later versions.

 

[KenGordon]

Suunto RGBM Dive Algorithms

Bruce Wienke is quoted on the site:

DR. Bruce Wienke:
“RGBM is the most realistic model in science. The parameters are correlated with real data of thousands of dives which makes it good physics, and the data is validated and correlated. I have been working with Suunto since the 90’s and Suunto’s progression from Suunto RGBM to Technical RGBM and now to Suunto Fused™ RGBM is a very natural one. The new algorithm is a supermodel that covers all types of diving.”​

I was talking about the HelO2 which predates the Fused stuff by three or four years.

My point, regarding the OP, is that there is a whole class of 'deep stop' fudges quite like the ones in his poll but implemented by the computer. While almost nobody is now manually doing Pyle stops it would have been interesting to see how many are following the computer ones.

In your article you say

• With the deep stops setting on, the Suunto RGBM’s first stop was deeper than suggested by the NEDU study. When the deep stops setting was off, the first stop was within the safe range.

which sounds like an agreement that this supposedly bubble model is not doing excessively deep stops.

I got as far as trying to figure out if I had to join EUBS or SPUMS in order to read that paper before getting dragged back to real work.