Deep stops in your Suunto ?

[DENLASCUBA]

The deep stop will become active once you descend past the 18-20m mark. The deep stop timer will then start once you reach 1/2 of your max depth upon ascent.

 

[Remy B.]

Ok, thanks, then I will expect it to activate almost every dive, I will leave it On for the added safety, just hubber around on the deep stop to kill time.

 

[100days-a-year]

Not a safety feature,an option.

As beaten to death on RBW and elsewhere,there is no credible evidence to suggest any deep stop is safer and several studies which show in the instances DrLector speaks of where the stops are deeper and longer to be less safe.Extrapolating backwards from those studies isn't as accurate as empirically testing every decompression model on divers for quantifiable incidence of DCS but it's what we got available.It is after all Decompression Theory and not Decompression Science.

Diving a Suunto in any case will likely be the only safety feature anyone needs as they are well known to be overly conservative.

 

[KevinNM]

My new vyper air has a deep stop option, which is off by default. That seems like a good way to keep it.

 

[boulderjohn]

Didn't read thru all the replies but like about everything that involves the 'science' of diving, you're going to find conflicting info. For instance, Eric Baker Clearing Up the Confusion About Deep Stops does not advocate deep stops. Richard Pyle however in Deco for Divers does.
Although this info is primarily for deco, I see no reason to not to follow the same reasoning for NDL.

Erik Baker does not really oppose deep stops in that article, which was written in 1998. Pyle's actual work was done even earlier. He did not write Deco for Divers--that book (by Michael Powell) just explained his deep stop methodology from the 1990s.

In a 2006 discussion in The Deco Stop, Pyle indicated that although he was no longer following the exact methodology he advocated in the 1990's, he was still doing something similar. Pyle did later participate in a 2008 DAN-sponsored discussion on Deep Stops that determined that there was not a lot of research supporting the practice. I have not heard of any more recent statements by Pyle.

This 2011 article by DAN's Dr. Peter Bennett supports the idea of using Deep Stops on recreational dives. This 2010 article published by DAN is less supportive of the idea of deep stops for recreational divers. Dr. Bennett was one of 5 experts in a panel discussion in that article, and he had the most favorable opinion, with some other of the experts opposed to it.

 

[Remy B.]

I guess it come down that, it has not been tested enough, not enough research, at the end nobody know for sure and it still is not an exact cience, plus the multiple variables of external conditions that are different in enviroment as in individuals

I'm not a doctor, nor an expert, nor cience person, but if we take in account our body is made by diffrent tissue / layers some softer some no so, some dryer some no so, some organs softer some other no so, then it seems that air will travel at different rates trying to escape all that, IMO it can't hurt to make a deep stop, at the end you still need to stop again at 10ft, the other factor will be use of air for that deep stop, plus the conditions in which you do that deepstop.

 

[Sevenrider860]

Diving a Suunto in any case will likely be the only safety feature anyone needs as they are well known to be overly conservative.

I think that is the bottom line... Deep stop or no deep stop really does not make a difference on a recreational dive profile using a Suunto computer. Follow the computer with the option turned on or off and your safety margin is still extremely high.

 

[EFX]

I guess it come down that, it has not been tested enough, not enough research, at the end nobody know for sure and it still is not an exact cience, plus the multiple variables of external conditions that are different in enviroment as in individuals

I'm not a doctor, nor an expert, nor cience person, but if we take in account our body is made by diffrent tissue / layers some softer some no so, some dryer some no so, some organs softer some other no so, then it seems that air will travel at different rates trying to escape all that, IMO it can't hurt to make a deep stop, at the end you still need to stop again at 10ft, the other factor will be use of air for that deep stop, plus the conditions in which you do that deepstop.

I think that is the bottom line... Deep stop or no deep stop really does not make a difference on a recreational dive profile using a Suunto computer. Follow the computer with the option turned on or off and your safety margin is still extremely high.

I'm beginning to see a few responses relating to the trustworthiness of decompression science (DS). Phrases like "not an exact science", "voodoo science", "not tested enough", "it's [ONLY] a theory", etc. are outright wrong or misleading at best. A theory is not a best guess as some layman are led to believe. A theory is a scientific framework in which facts and hypothesis are postulated. Bubbles beyond a minimum size and number lead to DCS. This is a fact and is not debated. Doppler testing has revealed the veracity of these assumptions and its methodology and the results it has produced are based on sound science. All the "external conditions", their amount and contribution, are based on assumptions that have a sound scientific basis that have been tested in part.

In regards to deep stops it's helpful to understand the reasoning behind doing (or not doing) them. Excess inert outgassing beyond what can be safely eliminated via the lungs leads to DCS. The source of the inert gas comes from the tissues and/or as existing bubbles in the blood. They can be characterized in decompression programs as dissolved and free gas models. In older computers only dissolved gas (neo-Haldanian) models were available. The general premise is to create as large as a pressure drop (gradient) in order to maximize the rate of offgassing without overwhelming the system. This is done using a non-stop maximum ascent rate (to minimize ongassing in slower tissues), and minimizing the depth of any safety (deco) stop. So called bubble or free gas models limit the size and amount of bubbles in the blood stream by imposing an intermediate or "deep" stop in the ascent schedule. The problem is the end result is diametrically opposite for the two models; a constant ascent rate leads to greater bubble formation and deep stops lead to greater ongassing in slower tissue compartments. The advantage of using a mixed deco model computer is that it manages these two rather disparate effects to achieve an optimum result -- keeping your worthless a** out of the chamber.

So, the moral here is NOT to add deep stops arbitrarily. More is not better. Adding a deep stop on a NDL dive especially if you've accumulated precurser DCS conditions could lead to DCS. I would suggest turning on deep stops and following your computer. On my Mares Puck which uses a modified RGBM (Reduced Gradient Bubble Model) requires a deep stop only for dives close to the NDL or into deco. The deep stops are one minute in duration. Mark Powell's book "Deco for Divers" is a good book for non-mathematical readers interested in decompression theory.

 

[Lorenzoid]

Setting aside the whole issue of the merits of deep stops, does anyone know whether turning on the deep stop option and executing the stops as indicated will cause the Suunto RGBM algorithm to compute greater NDLs on repetitive dives than it would if the deep stop option were turned off?

 

[RJP]

I got a Suunto D4i as a christmas present, I set the alarms, in one is the Deep stop alarms, in my Mares Punk Pro dosen't have this programable so far I know, do you use this future or it is pretty much annoying and I ratther leave this disactivated, with my mares only once it told me to do a deep stop, but it is something automatic no users input in this.

For what I understood in the Suunto manual if active it will tell you to do a deep stop every single dive, did I understood right ?

Now I have two dive computers so I will use them both when I hit the water, as a redundancy safety.

If you don't understand the thinking behind doing a deep stop... I suggest you don't use that feature.

PS - how will you be more safe with two computers?

---------- Post added December 29th, 2014 at 05:41 PM ----------

Diving a Suunto in any case will likely be the only safety feature anyone needs as they are well known to be overly conservative.

I can never figure this one out, though it's thrown out there all the time as gospel. I dive a Suunto Vytec DS and my buddy dives an Oceanic... which is lauded for being liberal as often as the Suunto is for being conservative. We've done hundreds of dives together and the Vytec has never once been a dive-limiting factor or otherwise been a meaningful impediment to our ability to exit the water together. In fact in Bonaire last week we did a 200ft planned decompression dive to the Windjammer. My Suunto gave me 1 minute more stop time than his Oceanic gave him for the same dive. In actuality I went to 201ft, he only hit 195ft, but I think our dives were fairly identical otherwise.

I don't know that I would consider an extra minute of stop time for a 79min, three-gas dive to 201ft to be "overly conservative."

I HAVE however found that the Suunto will penalize "bad behavior" more so than other computers... it seems to dislike things such as reverse profiles, saw-tooth profiles, rapid mid-dive ascent rates (especially deeper ascents) and similar.