Let me preface this by saying that I respect your opinion, Ron...and I think that your avatar is very cool.
After reading this post, if you don't entirely hate my guts...then I invite you to come out to San Diego for some cold water diving and apres-dive drinks. You are welcome to test-dive my Suunto computer alongside your Aeris Epic.
After looking at Suunto's home page, most of their newer models do give credit for deep stops.
You are correct. In fact, the company is utilizing the "deep stops" feature as marketing hogwash to entice divers to buy/upgrade a Suunto dive computer. Since their modified RGBM is a proprietary algorithm, I don't know the details of their implementation of deep stops. Perhaps the issue is moot since even deco experts admit that we still don't know what the optimal deep stop profile is.
However, not all of them do. The Cobra, for example does not. A computer that is considered multi-level profile capable that does not give one credit for slow ascents, or deep stops IMO is not doing it's job.
Kern brings up a good point. It may be possible for an ascent to be too slow. If you believe that pre-cordial bubbling by Doppler measurement can be used as a marker for DCS, then several studies show evidence of suboptimal ascent profiles involving ascents that were too slow. Thus, a slow ascent may not necessarily be better.
With regard to incorporation of the "deep stops" feature, I think we disagree. I interpret your statements to mean: "If a computer does not give credit for deep stops, then it's not doing its job." Ironically, I do not think your Aeris Epic computer allows the user to spread out a safety stop over one or more deep stops.
Please note that I am making a distinction here between giving "credit" for a deep stop and simply treating a deep stop as part of a multi-level dive profile.
Going into deco, and incurring an obligation that should not exist because the computer does not handle that is false. You also seem to be tripping over your statements. First you say that all computers handle multi-level profiles, then you say that some may NOT give credit for deep stops/slow ascents, and that should not matter. It can not be both.
First of all, I invite you to look into the few studies of deep stop profiles in humans and the mathematical modeling of decompression theory. Your current view of decompression obligations is a black-and-white, true/false one. As you delve into the research, I think your view will change. I'll just leave it at that.
Secondly, I have not contradicted myself. Please re-read my earlier posts. Yes, I said that pretty much every modern-day "dive computer" I know of handles multi-level profiles. Yes, I go on to state that "credit" may not be given for deep stops. By "credit," I mean decreasing the duration of a standard 3 min safety stop at 10 - 20 fsw by incorporating deep stops into your ascent profile. One statement does not contradict the other.
In case you're interested, a nice starting point for learning more about deep stops is
an essay written by Richard Pyle.
On the Aeris in *normal* dive mode, a 3 minute SS is always there. I've not tested to determine what happens if you ignore that stop.
I would recommend against "testing" your computer by disregarding all or part of a safety stop. As you know, that would likely increase the probability of DCS.
Simply do your deep stop profile...and then see whether the computer asks for a full 3 minute SS.
Please note that I'm making no judgment as to what constitutes a safe/unsafe dive profile here.
Saying the marketing is *Hogwash* means little. All manufactures have such marketing.
I agree that all manufacturers have such marketing. I think
Kern covered why I initially brought it up.
The Aeris/Oceanic algorithm is based on Haldane's theory. That is more liberal than the RBGM model. It's been working for me for many years.
I'm glad that you are comfortable with your choice of dive computer. Many divers out there have had the same result as you. That's the empirical power behind the deco algorithms being used -- that many people are using them without experiencing DCS.
In practice, for whatever the reason, I suspect that most divers rarely modify the level of conservatism of their dive computers...even when they should. Heck, probably very few even read the instruction manual cover to cover. These kinds of divers might benefit from a more conservative dive computer.
I want to be clear here. I am not bashing Aeris/Oceanic dive computers. AFAIK, the company makes reliable products. The only issue I have is that there isn't much software out there that makes them compatible with Macs. As the Mac market continues to grow, I'm sure this situation will change.
I have nothing against Suunto (other than their no mail-order policy which IS HOGWASH considering you can buy Suunto watches online throughout the world). I do think they are a lot more conservative, and as I indicated, one can always add conservationism into a profile, but if your computer is telling you to make a deco obligation when none is needed, or limiting your time at depth, that could be annoying.
I think we can all agree that the Suunto modified RGBM algorithm is more conservative than the Aeris/Oceanic algorithm. Every dive is a balancing act between maximizing bottom time and mitigating DCS risk. I actually own a Suunto dive computer, and I've never felt annoyed with its level of conservatism.
Ron, I am 100% with you on the whole mail-order issue. I think that policy is meant to stifle competition and fix prices. I can also see why Suunto would want to compartmentalize world markets so that they can charge more in the U.S. vs. some other country. FWIW, I believe that large drug companies use the same strategy. I could be wrong about this, but it must be an effective strategy to maximize profit...or else they wouldn't be doing it.
As always, dive within YOUR comfort zone, and be safe!
Absolutely.
As an aside, I hope that this thread inspires others to learn more about deep stops and deco theory. I know that I learn more with each new paper that I read. For recently published peer-reviewed papers, I recommend using a comprehensive database known as
Pubmed. I realize that not everyone has access to the full-text articles linked from Pubmed, but at the very least one can peruse the article abstracts.
Have fun and dive safe.
