Why does it seem important to many people here to get or have a certification for a deco stop?
If you dive in a way that might lead to short deco stops you should be able to do them even without a cert.....
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