Why is it that entry level scuba learners have a depth restriction of 18 metres.. Many gung ho diehard would be divers who don't have the knowledge about nitrogen narcosis may think it is a bravery issue to go dive deep,where it is actually a knowledge and control thing mentally.18 m and above is usually not deep enough for the water pressure to effect the onset of getting nitrogen narcosis and beginner divers may learn to gradually control their mindset as they increase their total underwater exposure building up bottom time.
Only through experience can an individual be more calm and controlled.It doesnt really matter how gutsy you may be,but if you are a total newbie scuba diver, you may not know what narcosis might feel like and hence not be able to anticipate its onset or recognise the symptoms if the diver suddenly ventures in to deep water and risk losing control or downright losing it , like ..getting totally stoned , zonked , smashed , and behaving foolhardily. All is fine and good if the diver in question is in control of their faculties but then if not,well, there is always drowning underwater to contend with.
Getting narc is a funny thing . Personally i have witnessed few incidents of divers getting nitrogen narcosis on my shift as a dive instructor chaperoning or supervising deep dives with supposed experienced divers who were supposed to be trained for dives deeper than 25 m.
I have seen narc divers with my own eyes while training beginner divers on an advanced diver course and bringing them to a depth of 30 metres,linger few minutes then give them some simple mental exercises to test their coordination and also to see if they are susceptible to narcosis at depth..
There was a guy who after few minutes in a stationary kneeling position on a sandy bottom at 30 m,as i was about to play a fingers game with him, i noticed a blank stare through his dive mask. He was just staring at the surrounding environment and you can pretty much tell,he wasn't totally there! Inquisitive little wrasse fishes were swimming close to his face mask,and then the next thing you know,he suddenly on a whim, decide to feed the little fishes......with air bubbles.....from the regulator ...that he took out from his mouth that which he was getting his air supply from...and started depressing the purge button so that the air bubbles will make the fishes happy with a bubble bath. To top it off , i suddenly could hear laughing coming from him , sounded like laughing at first, then it seemed to sound more like coughing or worst .choking. All in a matter of 10-15 seconds.
Yup narcosis rears its head. And another one bites the dust.Rephrase ,another chokes on seawater.Had to force the regulator back to his mouth ,sealing the mouthpiece with my palm and his lips depressing the purge air button (at least he isnt merely sucking in water when he gags,coz of the continuous air flow) and immediately start ascending slowly to a shallower depth. At about 12 m ,he snaps out of it .And on the boat, he said he could vaguely remember what happened but sheepishly had an attitude of "devil made him do it" kind of excuse.
Which is cool by me.
At least to me it was a situation where i had a bit of control over since i was physically within touching distance with him at all times. Meaning there was a risk but it was minimized to the fullest.
Better odds than another diver, who had the deep diver certification,showed the cert to me verifying that he had gone through deep diver training and a advanced diver course meaning that he could handle himself underwater in deep ,strenous or challenging conditions. Requested that he be guided to a dive site popular among advanced divers because of the beauty but at the same time known to be challenging as well during certain periods .
Also a deep dive site that maximizes at 70 metres to the bottom . Usually,i will guide divers straight down to level off at 30m where the most interesting stuff is and progressively go shallower till dive ends at about 13m top of the reef.
This 'advanced diver' with a group of 4 more jumped in with me and started to follow me down to 30 m as planned.There was a bit of a surface current and reef was in open water so i had briefed them that soon as we jumped in we had to descend as quick as we can to the reef and take cover from the current ,or we risk missing the reef swept off course by the current. Jump in swim straight down,don't linger on the surface,regroup underwater at the top of the reef and descend deeper to spiral around the reef as we tour the dive site.
There was good visibility of approx 20 m. Every diver managed to dothe first part, which also kind of loosened me slightly,because i thought that if they could do that individually,then there shouldn't be any problems since the tough part is over, the rest is easygoing ,just touring dive site. Every 10 mins or so i will look back as we
swam along giving OK signals making sure all responds with same . 20m paused. Was in front of group.Looked back,divers in buddy formation. gliding towards me,the advanced diver at that point had both his hands on his depth and air gages and compass, he was looking at it . and i thought , " good, a careful diver ,monitoring his profile at all times underwater".
Banged my tank to signal to elicit a response from him that all is good at 23 m. Got an OK,so continued deeper,looked back again at 25m ,Okayed everyone, all responded except for the guy who had both hands in front holding his gages..Assumed that he is on top of things and didn't hear my clanging of tank, arrived at a landmark at 25m where we had to turn right. so looked back at the divers to signal them to follow ,all responded again except for the guy who seemed to be too preoccupied with his depth gage and air gage coz it was the only thing he was looking at.
Felt at that point that i may need to be on a "just in case" state of mind, so swam to him, pinched him on his arm and asked if he was OK. The guy just seemed to snap out of some mind state,but he could respond with a OK. so i motioned for him to follow me ,and he OKayed and even nodded. So i relaxed and started to swim to position myself in the front of the group to guide them .
Looked back again , all seemed smooth in a tight group.
Arrived at 30m, another landmark for course diversion ,so paused to wait for everyone before changing course .
And right in front of my eyes ,i could see that as the other divers were following me in changing course,that guy was going straight, down , not looking at anything..and would you know it , he still was grabbing on to his gages seemed to be staring at it , same unchanged position but worst yet he wasn't levelling off but was swimming straight down.Everyone else was following me making a right turn at the landmark except for him who was not levelling off at all but just swimming and swimming, in one general direction , down deeper.
Furiously banged on my scuba tank to get his attention but all i see was a figure with both hands in front firmly clamped on to his depth and pressure gage.
Well,by then ,signaled the other divers to go shallower and stay together while i chased the stray. Had to fin so hard to go after him ,by the time i caught up with him,i was almost out of breath ,risking getting narc myself ,Actually i could feel the effects of the narcosis on my person,luckily i knew enough to fight it and stay alert as best as i can and not let it get to me, by that time , he had managed to swim down to 50 m from 30 and god forbid if i had not gone after him,how deep he would have gone on .!
And he still wanted to go on a straight course deeper down. Had to grab him by his arm when i caught up with him,, jerked him a little, but this time i am not letting go of my hold. Had to literally drag him by his arm to follow me back up shallower. Glad the other divers were really cool and knew to stay in a group and waited at the shallow part of the reef.
And of course, symptoms of the narc diver just evaporated as we ascended to shallows.
I can think of many instances witnessing divers getting narc. point being, nitrogen narcosis is not to be taken lightly.
Divers get killed not by nitrogen narcosis but by the effects of it while they are at depth. The silly things it causes a diver to do, one when in severe narcosis, just loses it and commits life threatening stupidity.
Even the best of divers do get narcosis, it is how the diver controls his state of mind by recognising the symptoms and making a super effort to stay alert and not let it take control.