ISE Minimum Deco & Safety Stops Discussed 

Hi Achim, Another classy, instructive and thought provoking video. I am definitely not a hater, but rather a lowly groveling enthusiastic supporter. However, I do want to play devil's advocate here and open another line of thought concerning Min Deco. First, lets harken back to Haldane's original principles, particularly rule #3 which states essentially that decompression should be initiated by a relatively significant pressure differential. This led to traditional staged decompression and rule three has been cause for much controversy in recent years. I know its old stuff, but bear with me... I read the situation like this: As a result of new tools to measure the movement of micro bubbles in the blood led by Spencer and others so-called "bubble models" became popular. These models encouraged waiting out micro bubbles during decompression. Then came "gradient factors" designed to reduce decompression stress. Then DIR people encouraged slower and slower ascents, Ratio Deco and other models and techniques to squeeze these micro bubbles into total submission. My interpretation of this historical trajectory may be overly casual and I'm not an expert on decompression but I'm going for the gist of the history here in broad strokes. Now comes the punch line (finally!). A Navy human subject research paper by Doolette, Gerth and Gault in 2011 compared different ascent models using human subjects (Navy divers) in a precisely controlled experimental study. They did this study fully expecting in an open admission of bias that slower, more graduated ascents would be vastly superior to traditional staged decompression models. However to their shock what they found precisely the opposite! They proved conclusively in their research that deep stops increased the incidence of decompression sickness! The title says it all: "Redistribution of decompression stop time from shallow to deep stops increases incidence of decompression sickness in decompression dives", Navy Experimental diving Unit, July 2011. This is on the web... Effectively these results would seem to strongly support Haldane's antique principle #3 regarded by so much modern skepticism. I am genuinely taken aback by these findings and was wondering what you make of it? Is this unexpected finding perhaps due to their particular type of Navy diving, the age of the subjects or what?

Very important concept Achim. As a technical instructor, I see divers shooting up to get to their 3 meter stop all the time, a few times resulting in DCS. Bad training. I dive the DIR mindset, but mainly in sm or with rebreathers, and I also like UTD's Min Deco, which is a similar concept. But I think the idea of building the curve even for NDL is better, whereas in MIn Deco, the idea is half max depth and then 1 min. deco stops every 3M/10'. For me, doing the longer stops closer to the surface is likely to clear out more Nitrogen, and it also trains the recreational diver to think with a technical diver mindset - that all dives are decompression dives. Basically, when we dive deeper, we just follow another kind of profile, but it's still just a profile (whether Ratio Deco, MultiDeco planner, etc.) and the idea that profiles are flexible and should be geared to the individual is of prime importance. Thanks Achim!

The only thing I would add just from personal experience is that it is easier to carry out deco stops between 9 and 6m depths. Not saying that 5m or 3m stops are bad just that at 3m you become part of the wave/swell system and it is slightly more difficult to maintain position. Holding an anchor chain/rope obviously negates this effect but 9m to 6m is a nice zone to be...comments?

I've never actually had that a thought thanks for opening my eyes

great video! I realize again and again that divers are not aware of the fact that you are not completely decompressed after a non deco dive diving bühlmann. however, the safety stop on the bühlmann table - as instructed by a lot of dive agencies - has nothing to do with decompression. it was added to stop people from ascending to quickly. if you ignore these safety stop, your repeterive group is not affected. Will def add these 123 idea to my nondeco dives! thx

Hello! I think these kind of topic should not be based on discussion when everyone go with their own receipts but science and research. And when it come to deco, there is a lot of believe and auto claims experts... On the other hand, I agree with you to push people to think about what they are doing and not thinking that a safety missing will kill them but a proper slow ascent is better.

Great video, I use the 123 system except I ad the 1234 if I am within 5min of NDL, and 12345 if I am within 1 minute of deco or deeper than 30m. [Added in 3m increments]

Hi Achim , I follow your videos and your wonderful explanation. I have a question: I bought a Maris Smart Air and went down to a depth of 40 and accidentally exceeded the limit. Then, numbers appeared in order from left to right 3 2 5 in the center of the screen. Can you explain the meaning of each number and thank you for your wonderful explanation

Shouldn't the stop times follow an exponential curve like 1-2-5 instead of 1-2-3? Just wondering since that is what most deco-algorithms seem to do, although there is already an exponential increase in pressure differential (environment - tissue gas) with the stop depths of 9m-6m-3m..

Simple solution for a complexe topic and for some of the most common mistakes/lack of knowledge.

hey it all depend on the type of dive and how you feel on that day but thats my opinion

What you say about adding 5 min on 10 meters and 5 min on 5 meters as safety stops ?? Thanks in advance Great videos

Ascent as slow as possible on your remaing gas. Nothing is forcing you to get out of water. I usually anoy all my dive buddies with my extremly slow ascents. I usually spend 10 minutes at 1.5 meters and end the dive with 20 or 30 bar. 60 to 30 bar I consume at 2 - 1.5 meter. Nothing is rushing me. Plenty of gas to do it safely.

Hey Achim, URL in video is wrong. All the best

At 1:46 : www.expl.com is the website of a pipeline company. Your agency's website is is-expl.com. You're welcome :)

Great, put out a video and don’t respond to any questions or comments at all. 3 years later and see if there’s any comment.