Deep Diving Specialty Vs Mid Depth Cold and Low Vis

[Nasser]

The thing about narcosis is that there really are several variables - environmental as well as personal that will affect your susceptibility. For example, I routinely conduct dives to 55m on air in warm water, with plenty of light and visibility and virtually no current... I hardly notice anything. However at times I have performed the exact same dives (or shallower) but in colder water temperatures and have felt noticeable effects. Environmental factors such as water temp, visibility, light, and work load at depth in addition to your own physical characteristics will all play a part. These can all change on a dive per dive basis... even at the same site.

If, however, I know that I will be diving to the same depth but doing a wreck penetration, or the water temp is colder, or there is going to be a significant work load (currents) etc.. then I will most definitely be on mix or if that's not available, not make the dive.

Therefore it's important to consider that your deep training coupled with experience should allow you to make a judgement call as to whether it is wise to perform any given dive by assessing the various conditions (personal and environmental) for that dive.

 

[dbulmer]

question removed

 

[Bob DBF]

The thing about narcosis is that there really are several variables - environmental as well as personal that will affect your susceptibility. For example, I routinely conduct dives to 55m on air in warm water, with plenty of light and visibility and virtually no current... I hardly notice anything. However at times I have performed the exact same dives (or shallower) but in colder water temperatures and have felt noticeable effects. Environmental factors such as water temp, visibility, light, and work load at depth in addition to your own physical characteristics will all play a part. These can all change on a dive per dive basis... even at the same site.

I would add that just because one does not notice any effects, does not mean that you are not affected. I find it easier to deal with a noticeable effect of narcosis than to mitigate the dangers of narcosis when the dive seems absolutely perfect and uneventful. Mitigating the dangers of narcosis when you do not notice the effects is essential when deep diving on air, because the no symptoms can change quickly.



Bob

 

[Nasser]

I would add that just because one does not notice any effects, does not mean that you are not affected. I find it easier to deal with a noticeable effect of narcosis than to mitigate the dangers of narcosis when the dive seems absolutely perfect and uneventful. Mitigating the dangers of narcosis when you do not notice the effects is essential when deep diving on air, because the no symptoms can change quickly.




Bob

Absolutely - I agree 100%.

 

[Jared0425]

I would tend to agree with most responses here on narcosis. Diving here in the Great Lakes, when I drop below 80ft I start to notice narcosis and I begin to get apprehensive. It's gotten to the point now that I don't do 200ft wrecks anymore due to dark narc (on air). While I was diving the ocean, 160 felt like I was at 50ft and I was more relaxed and had faster reaction times than in the lakes.

 

[Steve_C]

Did deep as part of adventure dives (SDI) in quarry which limited us to 65 ft (barely legal). Later did the deep cert in the ocean (85ft) (PADI). What I remember was that in the quarry I had to do a timed skill. I came up from the dive convinced that I had done it faster at depth than on land and ruined the instructor's teaching point. When we debriefed I found out that I had actually done it a few seconds slower. The fact that I do not think I am narced at a given depth does not mean I am not. You can think you are doing it just as fast when you are not.

 

[Remy B.]

The Course was with SSI, in Nederland, the really bad visibility ( last dive ) was at the wreck the "Serpent". ( but overall visibility here in Nederland sucks compared to Curacao but the experience was good )

I have been to 39m in Curacao, in my AOW, did two more times 36m in Curacao, did 35m in Indonesia 1000 Islands on a wreck with bad visibility probably 4 feet it was a little cold, and enter in littel Deco time ( at least in my DC no telling what was the guides DC ), I always check my gas and DC, but I'm talking only 4 dives below 35m, don't know if I will react bad in future dives below 35m I guess it is something that you don't know when it will hit you or if it even well at recreational depths.

The Instructor told me he will dive with me anytime, so that is a complement, I just take it easy when diving , I ask if he saw any signs of Narcosis in me since I don't feel any difference or know the difference, he said no.

Online I feel that the questions were a little lame, not demanding like a TDI online, but every agency have his own approach on the way of teaching and I respect them, I did learn the calculations for gas consumption and planing, that is what I got out of the course and I'm happy to had taken this course.

Do I feel in a better position for a Deep Dive, yes much more, but as well I feel this only grasp the top layer of deep diving, almost sure in a Tec course the layer will be exposed.

Was it a challenge with almost no visibility ?, honestly no, didn't feel any difference.

I asked a friend that is a BSAC instructor from Wales, and he told me yes it can make a difference under those conditions, same said the LDS where I took the course, as well I read this same comments here in SB, that is why I ask further, granted I was not cold, so that is one thing missing in the equation that probably did not trigger the narcosis in me.

 

[DevonDiver]

Depth increase pushes your comfort zone
Low visibility pushes your comfort zone
More complex procedures push your comfort zone
Overhead environments push your comfort zone
New equipment pushes your comfort zone

Narcosis and pushing your comfort zone are a bad combination

Cold water reduces dexterity
Exposure protection necessary for colder water reduces dexterity

Narcosis and reduced dexterity are a bad combination

New skills task-load your situational awareness
New equipment task-loads your situational awareness
Unfamiliar environments task-load your situational awareness
Low visibility task-loads your situational awareness

Narcosis and diminished situational awareness are a bad combination


..... you get the idea....

 

[geoff w]

... I always hear that there is a equivalence between diving at 40m in clear water and 20m in cold and low visibility, but what suppose one to feel different ?? I don't believe this can be taken as a rule of thumb.

I know the course is about learning how to plan your dive and gas, but circumstances at my point of view were not a challenge or it suppose not to be like this ??

Feeling different as in narcosis is just one factor to consider. At 20m, you're using up your breathing gas 3 times as fast as on the surface, at 40m 5 times as fast, so at 40m you're going through the gas you brought with you nearly twice as fast, so gas planning should be a big consideration. No matter how warm the water is, if you're diving wet neoprene will be almost half as thick, and hence less insulation value, at 40m compared to 20m. Another big consideration is bumping up against no decompression limits - you get a lot less recreational bottom time at 40m than at 20m.

Any diver can dive to 40m. Understanding all the factors involved, planning the dive, and then coming up safely every time, including narcosis, gas consumption, NDL planning, etc should all have been as big a part of your class as the diving

 

[Russoft]

I haven't actually gone beyond basic OW, but I've been on 28 meter dives that felt like a walk in the park. It was tropical ocean, and the water was warm and crystal clear.

Back in Minnesota, I'm not comfortable much below 12 meters as the thermocline sits around there and vis/light drops quite noticeably beyond that. At this point, I'm still getting comfortable diving cold/low vis water and won't take a deep diving / AOW class until I'm comfortable with these conditions.

While the ocean presents current, swells, and surge to deal with, quarries/lakes present cold water and low viz. I'm more comfortable with the former, so a deep dive in the ocean does not seem advanced, while a deep dive in the later conditions would definitely seem advanced. I imagine different divers are comfortable with different things based on their dive history though.

Of course, then there are those people who dive in all those conditions combined...