Diverman68
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Shearwater petrel 2 all I use.
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During the raging deep stops debate in the technical diving forum, I started a thread so that we could agree on a definition for the phrase "deep stop." That effort was a failure.
During the discussion among the experts in the 2008 DAN Deep Stop workshop that was intended to come to a consensus statement for the results of that workshop, the problem of the definition of the phrase was raised. They could not come to a consensus of a definition then, either. Some suggested just eliminating the phrase altogether. I think I am moving in that direction myself.
We all know that when we ascend, we must use some sort of strategy so that we can reach the surface without DCS. We all would agree that ascending a few feet and then stopping for 10 minutes is stopping too deep for too long. We would all agree that going directly to the surface from all but the shallowest dives would be stopping too shallow for too little time. Somewhere in between those extremes is the best strategy for that diver on that dive. The problem is we really don't know what that strategy is. Some people think that the first stop should be deeper than other people believe it should be. For me, that is all that is needed in a discussion, and trying to pin down a definition is not only unnecessary, it is counterproductive. In the raging debate in the technical diving discussion, that simple difference was missed by people who insisted that everyone follow their definition of deep stops rather than just talk about the search for an optimal decompression strategy.
The same defintions apply to technical deep stops. The difference is between those added to an existing plan and those already incorporated into an existing plan (like VPM or Ratio Deco). Believe me, since I have to teach all of this to my students, and since I have to do the dives that will use on theory or another, I have encountered the definitions and worked hard both to understand them and teach them. Right now, things are very much in a state of flux. In technical diving, PADI's standards require that deep stops be taught and used in the trimix class. That curriculum also requires me to teach students to stay on top of the latest research. I wrote to PADI and told them that my reading of the latest research, which I share with my students, tells me not to do deep stops as defined by and required by the curriculum. Their response was that I was doing exactly the right thing by discussing the latest research with the students. If we decide that this research is going against deep stops, I am justified in skipping that standard. So far all students have agreed that we should not be doing those stops.Generically, these could be called no deco or recreational deep stops and deco or technical deep stops. For no deco deep stops, the stops are deeper than are prescribed by the decompression algorithm (no stop or SS). For deco deep stops it is not so clear. VPM generates a profile including what are called deep stops. One can accomplish the same thing by choosing a low GF lo when utilizing Buhlmann with GF. For me, recreational deep stops are some amount of time at around half the maximal depth. I'm not at all sure what technical deep stops are
I guess the point of this for a no-stop dive will be that it doesn't matter what kind of stops you make during the ascent and whose name or study is cited in the manual (whether conclusive of inconclusive)..... It's all marketing. the difference is going to be marginal and statistically insignificant.
If there were a really compelling study that showed that the NDL's we have right now are fundamentally wrong, then we would have new algorithms, not new "bells and whistles". In the technical context there IS a legitimate discussion right now (has been for several years) because there is irrefutable proof that RGBM is broken ... IN THAT CONTEXT.
For recreational divers, studies like Morroni seem to suggest that we have a choice, but the fact of the matter is that it's all "drawing bright lines through a grey area". It is FAR more useful for marketing than it is for divers.
R..
I will do that if the dive is deep(>30m) otherwise I just do a very slow ascent after a 5mins safety stop at 6m.As a side note does anyone do the 1 min stop at 3m or is it just me?
3 min at 6m, 1 min at 3m as the most bubbling off occurs there.
Extra safe or not worth it?
If you are padding the stops you are not diving DSAT. You are diving something you have made up which is probably more concervative than DSAT and so says nothing about how effective DSAT is.My Oceanic computers offer an optional deep stop for no deco dives only. It is a 2 minute stop at half the maximum depth of greater than or equal to 80 feet. The owner's manual cites the Morroni & Bennett study. I have never utilized this option. I do spend an extra couple of minutes at my SS if I have come within several minutes of deco. When doing light deco, I pad the shallow stop by 3-5 minutes, kind of like adding a SS after clearing the deco obligation. I dive the DSAT decompression algorithm. So far, so good, for me
Generically, these could be called no deco or recreational deep stops and deco or technical deep stops. For no deco deep stops, the stops are deeper than are prescribed by the decompression algorithm (no stop or SS). For deco deep stops it is not so clear. VPM generates a profile including what are called deep stops. One can accomplish the same thing by choosing a low GF lo when utilizing Buhlmann with GF. For me, recreational deep stops are some amount of time at around half the maximal depth. I'm not at all sure what technical deep stops are
If you are padding the stops you are not diving DSAT. You are diving something you have made up which is probably more concervative than DSAT and so says nothing about how effective DSAT is.
OP, these 'deep strops' are essentially a type of safety stop. Mostly they force a diver to control their ascent rate by actually stopping. By and large they can be ignored and perhaps the computer will add a minute at the final stop. If you have done a 42m dive and you get a minute at 22m and two at 11m it is unlikely you will on gas significantly at those stops. If you do those stops, then you will not have done a 20m/minute ascent to the surface. Avoiding such a fast ascent is worth while in my opinion.
Deco is a game of dice. People do get bent doing 15m, 45 minute dives. The idea is to reduce the incidence to an acceptable level.
The NEDU study mentioned above, is about trading deep time for shallow time. That was a particular claim made that by doing stops deeper then you could do less time overall for the same time on the bottom. That is not the case with these deep safety stops which are about extra stops, just deeper than 6m.