Yuri accident

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yeah you notice if you have to add air or not while descending and havent had problems with that , its just i was not sure if at some point , say 50 metres, its more difficult to stop yourself from descending .

---------- Post added July 13th, 2014 at 11:20 AM ----------

but yes, control BCD and if its not enough drop weights
 
Storker, I think you might be diving a bit overweighted.
Depends on how you define "overweighted". I've been working up my weight in steps since my first dive in that suit, when I corked from 18m with about half tank. The weight I carry now is about 2 kg more than the absolute minimum I need to be able to hold my safety stop with 50 bar left.

I prefer not to feel totally shrink-wrapped at the end of my dive, and a little air in my undergarment keeps me from getting cold in single digit (C) temps. If that's "overweighted" for you, I think we'll have to agree to disagree :)
 
Storker, I'll retract my comment addressed to you, not realizing you dive dry. I dive wet and rarely ever have to add any air at any time. Perhaps others that dive dry will have some comments in regard to your posts. (Msybe some will have comments for me, :wink: )

Tatiana, sounds like you have a feel for it. :)
 
so now you guys are talking about the difference diving dry and wet... i guess in uk i will have to use 7mm or dry like someone said in the forum . what differences should i keep in mind? weight , buoyancy and something else?
 
Storker, I'll retract my comment addressed to you, not realizing you dive dry. I dive wet and rarely ever have to add any air at any time. Perhaps others that dive dry will have some comments in regard to your posts. (Msybe some will have comments for me, :wink: )

Tatiana, sounds like you have a feel for it. :)

thanks for reassuring me, i rarely have to add air to my bcd too, at least not until i'm past 50ft, i thought i'm doing it wrong



This includes the air in your BC and the little trapped nitrogen bubbles in your wetsuit

there's nitrogen in the wetsuit?
 
hi all,

I was watching a tv program call Monty's diving mysteries i think and one of them was " the divers graveyard". It was about the Blue Hole in Dahab and why so many divers died there. The so sad accident of Yuri Lipski appeared on the show.

One of the worst programmes about the place i've ever seen. Utter utter hype combined with idiotic "theories" to explain the mundane. Dressing Tariq Omar up like something out of Lawrence of Arabia was the last straw.

My question is , why was he sinking so fast ? is there any depth where your speed increases because of pressure? was he overweight? I dont seem to understand it.

He did pretty much every thing wrong and wasn't sinking "too fast". A normal descent rate in there is the region of 40m/min purely to maximise your bottom time. He was using the wrong gas, with the wrong equipment with no dive plan or clue and ultimately and not-surprisingly had an O2 hit probably brought on by the extreme narcosis and CO2 retention from the effort to move around. An incident that proper training, equipment and planning would have avoided.

You accelerate as you sink on a dive due to the wetsuit compressing and losing buoyancy (along with the air in your bcd/wing). That's why you need to add air on descent and dump air on ascent on any dive you do. (Open water manual, chapter 1 - pressure/volume relationships). Your speed increases the second you leave the surface.

The blue hole is a very safe, easy dive site for all levels of diving. It has little to no current, is sheltered from the weather,warm water with very good visibility. It's about as benign as you can get. Hundreds of people do the recreational 30m or so dive every day there and tens of people do the 50m arch or bottom on a daily basis all without incident.

Yes lots of people have died there and almost all of those are easily preventable. Normally its Russians or eastern Europeans going way beyond their training, usually using air, getting into trouble and ended up dead. I've been ascending through 85m there before now to be passed by 1 Egyptian guide and 2 Russian customers on single 12l tanks of air with gecko computers going the other way and this isn't uncommon.

Although there are some genuine accidents there as there are with any 100m or so tech dive the vast majority come down simply to human stupidity and are completely avoidable. No need for warped theories about disorientation, magical mermaids, vicious currents or giant octopus which that programme tried to claim - its a deep side, people do it on air, the get narcosis, they get deco, they dont have enough gas, they die.
 
Granted, I have only about a dozen dives in a wetsuit, so I can't speak with any authority about optimal weighting while wet, but my standard tanks' buoyancy swing from full to empty is between 3.2 and 3.5 kg. If you're weighted to be neutral at safety stop depth with an empty tank, won't you be as negative as your tanks' buoyancy swing at the beginning of your dive? Or, at least, between three fourths and five sixths of that if you choose to be neutral with 50 bar left. So, by that logic, I should be between two point something and three point something kilos negative just after submerging to safety stop depth, even in a wetsuit.

What am I missing here?
 
so now you guys are talking about the difference diving dry and wet... i guess in uk i will have to use 7mm or dry like someone said in the forum . what differences should i keep in mind? weight , buoyancy and something else?

The thicker the neoprene the worse the problem with compression. In a drysuit you still need to add air as you go down to avoid accelerating (and being shrink wrapped). I'd never recommend anyone use a thick wetsuit over a drysuit due to the buoyancy issues - they need a lot of weight to get under initially then compress losing a lot of buoyancy so at depth you're really negative. That in return means you're filling and dumping more often, using more gas and buoyancy is harder. In the UK as well i wouldnt class a 7mm (or 7+7) as warm enough to keep you comfortable or safe in a lost-at-sea situation. I stopped teaching BSAC students in Wetsuits before June and after October for that reason here.

As above though, this basic physics should have been taught on day 1 of your open water or ocean diver course.

---------- Post added July 13th, 2014 at 07:45 PM ----------

Granted, I have only about a dozen dives in a wetsuit, so I can't speak with any authority about optimal weighting while wet, but my standard tanks' buoyancy swing from full to empty is between 3.2 and 3.5 kg. If you're weighted to be neutral at safety stop depth with an empty tank, won't you be as negative as your tanks' buoyancy swing at the beginning of your dive? Or, at least, between three fourths and five sixths of that if you choose to be neutral with 50 bar left. So, by that logic, I should be between two point something and three point something kilos negative just after submerging to safety stop depth, even in a wetsuit.

What am I missing here?

A 12l tank holds about 3.5kg of gas so that's 3.5kg of extra "weight" at the start of the dive. Assuming the human body is uncompressable, the BCD is perfect and no wetsuit a perfectly weighted diver would start the dive 3.5kg overweight which would allow them to still be neutral with an empty tank at the end of the dive.
However, other factors kick in, the buoyancy of the suit, hood and gloves being the main one. These are buoyant but compress so lost buoyancy at depth. That means you need extra weight over that 3.5kg to leave the surface. The thicker the suit the more extra weight you'll need to do this. With a really thick 7mm+7mm wetsuit, hood and gloves that can easily be 4-5kg extra (my hood and gloves provide 1.2kg salt water buoyancy for example) so would be submerging about 8kg "over". To use a more extreme example, on some tech dives the air in my tanks weighs in at about 20kg so i start a dive 20kg heavy at least.

As for weighting, neutral with 50bar is never a good idea. Its a reserve you MIGHT have to use either for yourself or a buddy. The last thing you want during an air share or problem is to be positively buoyant and unable to do a safety stop. Properly done i'd say be able to be neutrally buoyant with pretty much no air in the BCD at 3m with a virtually empty tank. If you're exactly neutral (near no air in the BCD at 50bar), add on about 0.5kg so you can be neutral on empty.
 
In the UK as well i wouldnt class a 7mm (or 7+7) as warm enough to keep you comfortable or safe in a lost-at-sea situation. I stopped teaching BSAC students in Wetsuits before June and after October for that reason here.
If you're planning to do any diving in UK or Nordic water temps, I recommend taking the OW course in a drysuit. That's SOP up here.

At the level of skills the average OW student has, learning to control a drysuit is just a small increment in task loading and frustration. After finishing the course, you should have both the basic skills you get in a warm-water course, PLUS the ability to dive in a drysuit. And you won't have to pay for a drysuit course later :)

As for weighting, neutral with 50bar is never a good idea. Its a reserve you MIGHT have to use either for yourself or a buddy. The last thing you want during an air share or problem is to be positively buoyant and unable to do a safety stop. Properly done i'd say be able to be neutrally buoyant with pretty much no air in the BCD at 3m with a virtually empty tank. If you're exactly neutral (near no air in the BCD at 50bar), add on about 0.5kg so you can be neutral on empty.
I like this reasoning :) I haven't done this kind of analysis myself, but I didn't feel comfortable when I was almost struggling to keep neutral at the end of my dive with ~50 bar left. For me, about 2 kg on top of what is normally taught as minimum weighting makes for a much more comfortable dive, both physically and psychologically.
 
The "float at eye level" we have to teach in OW is in reality very inaccurate. For AOW formulae for calculating a baseline are even more out. The only weighting solution is to actually go in with some spare weights and clips and actually measure it. Neutral with 50 bar, now add some surge or swell - good luck trying to hold that now!

Best way is take some spare weights to the line or safety stop area with you and at the end of the dive with a buddy, empty the BCD, remove some weights until you're just about neutral with a tiny bit of air in the BCD. Then add 1/2kg or so to account for the 50 bar. The shallower you can do this the better, 2-3m is better than 5-6 (due to the wetsuit compression issue above). I really dislike people using very thick suits in cold water. It just makes everything more uncomfortable and harder for them. If you need a 2 layer 7mm what you ACTUALLY want is a drysuit.
 

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