Going into Deco as Rec Diver

[NothingClever]

@The Chairman - Do we need to run a bake sale to raise money for coffee for the Moderators?

This is Basic SCUBA and we’re saying dumb stuff.

 

[sena_akutsa]

After reading through all posts, my conclusion is it mostly depends on the Learning approach, which is different
from Centers that "forbid Deco and depths below 30M" to Other Centers that insist on teaching deco, in order to Avoid any accident in case a diver encounters such a sircumstance.

Our trainer taught us almost from the very beginning: controlling ascend speed, keep accurate depth during minutes without struggling at 6m and at 3m, always keep an eye on our air consumption, deploy DSMB, ...and read & understand indications on at least three different DC s: Cressi Leonardo and Mares Puck Pro that we use in the club, Suunto D4i and Scubapro G2 that he uses himself.

Once everyone understood how things work, we several times reached "short deco" stops like 8 min (5 deco + 3 safe); these were ALWAYS planned before and we used 15L tanks on purpose.

"average RMV" became part of our exercices after N1/CMAS 1* , especially last year when we started class for "PA12" certification (autonomous diver up to -12m).

The trainees who bought their own, opted for a Mares Smart as first DC (same display as Puck Pro),
then to learn reading it is easy to "force deco mode" by setting safety factor to SP2/P2/P++ , and dive constantly comparing it to a secont DC with "standard settings" borrowed from the club.

I did so, several times when I was offered my MaresQuad

Mares Quad set to P++ compared to Leonardo set to SP 0

 

[arkstorm]

Some thoughts and observations...

"Going into deco" is not a fixed threshold because it is dependent not only on the dive profile, but also on the algorithm being interpreted by the DC and on conservatism settings.

That having been said, if you are using a reasonably modern DC with appropriate conservatism settings and you find that your dive profiles frequently put you into deco unintentionally, you should consider adjusting your dive planning because you are probably diving at the wrong edge of the safety margin.

Planned deco diving involves sufficient redundancies so that if the SHTF, you (and your team) will still likely be able to complete your necessary stops and ascend to the surface safely.

Unplanned deco dives place you in a situation where only if everything goes right 100% will you likely be able to complete your necessary stops and ascend to the surface safely.

It is relatively easier to visualize and assess the risk associated with diving in an overhead environment when a physical barrier such as a cave or shipwreck blocks your direct ascent. Deco diving places an artificial ceiling upon you preventing a direct ascent without doing the required stops, no different than if you were in a physical overhead environment.

Recreational sport diving enjoys a stellar safety record because the margins of safety are great if you stick to NDL. Safety margins diminish rapidly beyond that.

If you want to dive deco profiles, do yourself a favor and obtain the training, skills and equipment necessary to be safe.

 

[34109411]

I started with PADI OW then went and did BSAC sports diving which is deco trained diving in the 1980's. Deco diving is still recreational diving for a lot of agencies. I don't do a lot of deco dives but recently in Maldives the guides were leading people and they would go into deco on dives. First time I've really seen a PADI dive shop where the guides will exceed NDL on a regular basis.

Also they are using SUUNTO so they go into deco before my Perdix AI.

i take a shower with my suunto and go into deco.

 

[SouthernSharktoothDiver]

I don't have a deco certification, but I think about this sort of thing a lot, and IMO, a deco certification is generally a good idea ("Necessary" is something people can argue about till they run out of air) because it reduces the chance you do something stupid in terms of gas management, and it better prepares you for something going wrong.

Like, with a modern dive computer, a well trained monkey could figure out how to clear their deco obligation. Just stop when the computer tells you to stop, and go when it tells you to go. That, in my (unqualified) opinion, is not the issue. The issue is in making sure your deco obligation does not exceed your air (which, if you know your sac rate, could be managed without a class, but do you really wanna cut corners here?) and in learning what to do if, say, your computer dies at depth or you run into adverse currents or any one of quite a few other potential issues I'm sure I'll learn about when I get around to taking the class.

If nothing else, what pops into my head is that while I know my DC will tell me how much deco I've got, I don't know how much bottom time past NDL adds up to a minute of deco, and I don't much care to trial and error or self study my way into the bends. I'll stick with the NDL diving I'm trained on, and encourage others to do the same.

 

[Blackcrusader]

Like, with a modern dive computer, a well trained monkey could figure out how to clear their deco obligation. Just stop when the computer tells you to stop, and go when it tells you to go.

Well you see that's not how it works. Many divers using Suunto get themselves locked out because they do not understand their DC's. Seen it many times... divers saying their DC is stuck lol I'm always amused when I hear divers DC alarms going off while they point at me. My Perdix does not have audio alarms but hey, never stopped other divers who do not know the sound of their own alarms thinking what they are hearing is coming from me lol. Too many divers just slap on their DC and don't even know what settings they are using.

Also with multilevel diving a deco obligation can be cleared during the dive without specifically just going up to the ceiling of a deco stop. Just because one has been in deco does not mean they ascend to the deco stop depth and end the dive.

It's pretty rare that divers do a square profile dive matching tabled or a planned deco dive.

 

[johndiver999]

. Deco diving places an artificial ceiling upon you preventing a direct ascent without doing the required stops, no different than if you were in a physical overhead environment.

Not really. You can easily violate a deco ceiling without any consequences... not comparable to an overhead.

 

[sena_akutsa]

Not really. You can easily violate a deco ceiling without any consequences... not comparable to an overhead.

Our dive instructor was clear :
the Only reason to violate a deco ceiling should be "to avoid an immediate death", like drowning or severe injury.
Then, upon reaching the surface, the Emergency procedure must be strictly followed, regardless the diver's sayings "feeling all right" (before any DCS symptom).

 

[Scubagermany]

Perhaps I can give you an example. Last month in Maldives a newly minted DM who got his DM Cert in Thailand had only done a few dives deeper than 30m. He had around 200 dives. He brought his GF along on the dives and she had AOW but only 25 dives.

One one of the dives he saw a guide dive deep and rushed to descend and did not pay attention to his beeping DC or his SPG. So he goes into deco and he had very poor gas consumption. So he's at 45m depth and has only 80 bar left after a short time. Guide realizes this diver is not paying attention so shares air with him and brings him back to the ceiling required for the deco stop then puts him back on his own air. Back on the boat the DM had no clue. But he was being the Macho Hero diver to his GF cause she thought her BF being a DM meant he knew what he was doing. She even said her BF would give her dive debriefings. So I pull the DM aside and ask him why he lost situational awareness? HE's like well I was excited to dive deeper than 40m as could not do that at the sites in Thailand as sites depth limited by seabead.

I ask him how many liters of gas in an AL 80 with 210 bar? He replies no idea but an AL 80 is a 12 liter tank. I ask really? You are a DM and don't know the actual size of the tank I said go take a look at the stamping on the tank. Oh he says only 11.1 liters. So then I ask him what he thought his sac rate was? Sac rate he asks with the face of this does not compute. Never heard of SAC rate. So I ask so how many liters of air do you think you use per minute at say 5m depth then at 45m depth? No clue.

I had a word with his GF the next day as he was not diving due to bad head aches. I told her following her BF on dives was dangerous as he does not know what he is doing. She realized I was correct and said yeah she just went where he went without looking at DC or air. She was OK on air. I said did you realize you how deep you were, much deeper than 40m depth. She replies no she never went that deep.

I showed her a video of her following her BF and I was at 40m and they were deeper. She didn't know her depth or the fact she had been in deco. Her BF also did not understand the DECO being displayed on his own DC. She just followed her BF cause after all he has that DM cert.

When people are not trained and decide to go on dives at deep depths and do not understand their gas consumption or DECO this is when people can end up being hurt.

What happens when a diver goes into deco for 10 mins after 50 mins afters staying at deeper than 20m on Nitrox? Do you think they have enough gas to safely complete the dive? Many divers would not.

This is why training is important. Can people do deco dives without a cert or training. Sure they can. There are no scuba police. You might get told you cannot dive again that day. My buddy and I asked that the DM be removed from our dive group and he was. He was put in a group with no so good consumption and had shorter dive times. He was miffed that he was not in our group for a 70 minute dive.

I said you were on the same dive and were back on the boat after 45 mins with 40 bar how did you think you could do another 25 minutes dive time? lol

You just gave an example of how someone with the training of a DM gets into trouble for either being stupid or careless.
Its the opposite of training educating the diver.
I have less training (formally) and more knowledge and skill than he does.

 

[Centrals]

It's pretty rare that divers do a square profile dive matching tabled or a planned deco dive.

LOL.
You had never dived any big wreck. So naive.