"Accidental" Deco

[Rhone Man]

I do think it's important that divers know that going into deco is not a death sentence or a reason for panic.

It reminds me of a very good dive briefing I had when in Truk. The first dive the following day was going to be particularly deep, and the crew warned everyone in advance, that if you do that dive you will inevitably go into deco. Accordingly, what they advised was that on the last dive of the previous day, anyone who had never previously gone into deco should set their computer to air (everyone on the boat was using nitrox) and at the end of the dive, sit in the sand until their computer went into deco.

They said (and I can readily believe) that many divers get a "panic response" the first time that they see their computer flip into deco. If you see it for the first time in a controlled environment when you know you are not actually in deco, you are likely to react better when you see it the first time "for real" the next morning.

 

[DuboisP]

The poor guys, they surely must have been using Suunto's

i'm using Suunto, and a lot of divers use it.
CMAS divers are trained to decompression dives very early in their courses, at the 2nd level (a little more than AOW).
at the 1rst level, they always dive supervised.

 

[DuboisP]

Here's what V-Planner (VPM-B +2) would have to say about an "oops" recreational Caribbean-style dive (120ft for 22 minutes): 1 min @ 50ft, 1 @ 40ft, 2 @ 30ft, 4 @ 20ft, 7 @ 10ft.
The dive time and depth were picked to illustrate a diver who goes just a little bit deeper and a little bit longer than they intended, and racks up the 15-20 minutes of deco in your example.

VPlanner VPM-B + 2, tells me : 2 min @ 50 ft, 3 min @ 40 ft, 4 min @ 30 ft, 7 min @ 20 ft, 12 min @ 10 ft, so a deco time of 28 min
VPlanner is not accurate for AIR or Nitrox dives, as it's a software for diving Trimix
with the tables generally used in France for training (and sometimes for diving), calculated for 75 ft, I have 2 min at 18 feet, 19 min at 9 feet, so a deco time of 21 min.

 

[DevonDiver]

VPlanner is not accurate for AIR or Nitrox dives, as it's a software for diving Trimix

Keep saying it... but it doesn't make it true.

They said (and I can readily believe) that many divers get a "panic response" the first time that they see their computer flip into deco. If you see it for the first time in a controlled environment when you know you are not actually in deco, you are likely to react better when you see it the first time "for real" the next morning.

I think this is going to become a greater reality as the emphasis on dive tuition progresses to become more computer-centric in the coming years.

Back in the days of tables, most recreational divers had no option with deco - other than to complete a statutory hang and then stay out of the water for a prescribed period. Accidental over-stays were penalized by missed dives. Going into deco was seen as a major issue, which (most) tables provided no definitive answer to or explaination of.

That is no longer true as dive computers have become the norm... and consequently, turn emergency deco from a major inconvenience into an 'easily rectifiable glitch'.

It's important that divers understand their dive computers, so that they can react appropriately to the information and guidance that it gives them. That said, it is also important to ensure that using dive computers does not create a slide in perception about the dangers of entering deco. I would predict that, in the future, divers' perception of entering deco is likely to become far less severe than it currently is.

Where divers are taught to use computers at entry-level, or beyond, it is critical that they understand all aspects of that computers operation. Emergency decompression needs to be taught with computers, just as much as it ever was with dive tables... that means some exposure to the computer's deco screen is necessary. Entering emergency deco should lose it's 'fear factor'. But....to balance this, more educational emphasis on the reasons to avoid entering deco needs to be provided.

 

[FinnMom]

i'm using Suunto, and a lot of divers use it.
CMAS divers are trained to decompression dives very early in their courses, at the 2nd level (a little more than AOW).
at the 1rst level, they always dive supervised.

I'm CMAS** and don't recall being trained to do deco dives. What did I miss?

Yes, I have read that CMAS* divers are not certified to dive together, but that's pretty darn conservative. CMAS* is the basic course and is much more through and involves much more instructor time & attention than with the hugely more widely used & commercial certification programs. At least to my experience, CMAS training is through clubs, training their own members at next to cost, instructors all unpaid & just working for the benefit of the club. CMAS* divers with 15-20 dives under their belt are well qualified to dive together in comparison to most "baby divers". Esp. here in the noth where they probably trained from day 1 in drysuits, cold water and poor visibility. I've only once in 5 years seen 15m vis.

 

[Kern]

VPlanner is not accurate for AIR or Nitrox dives, as it's a software for diving Trimix

Oh dear, I'm gona die.

 

[DevonDiver]

I've heard that VPlanner is not acceptable for use with split fins.... but never for non-trimix dives.

 

[divebat]

I have been told repeatedly in OW and AOW classes the danger of DCS as well as dive well within the limit(ndl) BUT never what to do IF...... Decompression is absolutely NO.

Wow In my OW class it was emphasized over and over that as a recreational diver you do not go into Decompression, but we were still taught very clearly what to do if it happened.m I would think that would be a standard part of any class and panic control is a learned behaviour that IMHO should be learned by all people who engage in Sports where you may not be able to immediately stop playing and get out of a situation (Diving and caving are two that immediately come to mind).

Even the most calm and adventurous person has their triggers. I have seen people freak out out over relatively minor things and almost get badly hurt. Learning to control panicky reactions in a non-diving situation can help when you are 100ft down and something unexpected happens.

on another point- Before I owned a computer I rented. I found the manual for my rental on line and I printed, read and highlighted, re-read, and read again and worked with the controls so that I understood the basic functions and the display well before I took it out into open water. With my current computer I refresh my memory on it before every dive trip and make sure I can read Depth and remaining dive time at a glance. I also check my gauges regularly and I make sure my dive buddy checks theirs as well. When I am at 2/3 and 1/2 and 1/3 tanks I ask what their air supply is at and tell them mine.

 

[Rythmmaker]

On a dive last week in Roatan, one of the divers on our boat got into deco on the second dive of the morning. We had all done a deep wreck dive only an hour earlier, and I don't think this diver was paying attention to his dive computer on this dive; he had less than 500 psi remaining when the dive master caught up with him, read his computer (which was emitting a constant alarm) and realized he had a 17 minute deco obligation.

Fortunately, our DM had plenty of reserve gas, because they had to share air on the ascent. He finished the deco stops, and got back on the boat with less than 200 psi in his tank.

Everyone else had been back on the boat for quite a long time when they finally surfaced. Since the diver in question had made joking comments previously about how high his SAC rate was (and he was normally one of the first back on the boat), when he was still in the water long after everyone else had surfaced and been recovered - there was quite a lot of anxiety and concern for his safety among the rest of us on the boat.

Dive master earned his keep for real on that dive. If not for him, the diver would not have had sufficient air to complete his deco - and to the point of this thred - I'm not sure he knew exactly why his computer was sounding the alarm - or what to do about it.

 

[sbissell3]

Two years in a row I was on a dive boat in Cozumel with two guys from Texas who routinely went into deco on every dive. Their reasoning was that since they used nitrox it didn't matter. Nothing the DM or I could say made any difference to them. In the end one of them said that he didn't really believe in decompression sickness as he had never encountered it himself. There is no way to deal with such stupidity. Finally the owner of the dive operation offered to give them their money back, which is a big deal right now in Cozumel.