Dive tables for accelerated decompression

[Soloist]

I would like to be able to get a reasonable / maximum amount of bottom time in the 40 to 50 m range whilst keeping the overall dive time to 50 to 75 minutes.

Even though it was aimed at me I thought the joke about letting Darwin's theory of evolution take its course was quite funny, that is why I "liked" it. Getting back to the original topic Neil is right to some extent, although I would use the words at minimal cost and minimal complication instead of "on the cheap". Nitrox 32 is limited to about 33m but gives a useful increase in NDL time compared to air. When diving to depths greater than 30m BSAC require a back up gas supply, some other dive centers / agencies require a personal pony or a spare cylinder on the shot line at say 6m. There are two things that limit your time at depth, quantity of gas and NDL. Suppose all you want is a bit of extra time and safety margin on that wreck that sits on the bottom at about 45m. What I envisaged was having 15L of air on my back but instead of having 3 Kg in my LHS weight pocket hang 12 L of Nitrox 32 complete with regs on my left hand D rings. I descend using the nitrox to about deck level say 25m, then I change regs and have a decent length of dive round the deeper parts of the wreck until my air is down to say 100 bar. I then ascend to less than 33m and change back to nitrox to extend my NDL and explore the upper parts of the wreck.
The above method means I get a good length dive, at all times have a good supply of back up gas and minimize my nitrogen build up.

Do you enjoy playing Russian roulette in the comfort of your home, strolling on the beach, at the pub or just when diving? Please get certified in decompression procedures and advanced nitrox.

 

[dewdropsonrosa]

I'd like to quote myself from a different post on a similar topic:

Speaking from the perspective of having completed AN/DP six weeks ago [NB: as of the time of this comment], you really do need the full extent of both classes' theory and practical training to be safe. Decompression diving is a much more complex game to play.

Fully appreciating, planning for, and assuming the risks of decompression requires understanding of gas kinetics and behavior, human physiology and compressed gases, gas planning, underwater problem-solving due to the 'soft' overhead, rescue skills and decision-making, on top of highly polished diving skills.

On your hypothetical dive:

• Do you know how long that single tank will last you at your target depth? Do you have the information you need to calculate that?
• Can this dive even be safely completed on a single tank? Where's your redundancy?
• Do you know how much deco gas you'll need to breathe? How much you'll need to bring for contingencies?
• Do you know the MODs of all your gases and when you can safely make switches? Do you know the procedure to make a safe switch?
• Do you know how you'll need to modify your decompression schedule if you're delayed in returning to the surface? If you come back sooner? Without blindly trusting your computer?
• Have you considered environmental hazards (temperature, surface conditions, changes in weather) for the extended duration of your dive?

Most OW training doesn't prepare divers to do this. I wasn't prepared to do it before I took the class. Technical diving requires technical training!

 

[happy-diver]

Right, so you have to be able to dive, read, and afford multideco

so if 60plus can do those things his two bottle plan is acceptable

 

[Celt]

Short answer IDECO PRO, but your trying to cross to many bridges at the one time. If air is your bottom gas then you need to be able to complete the dive on air including deco and redundancy if solo. Then look at ways to extend the bottom time and shorten the stops.

 

[Marie13]

Do you enjoy playing Russian roulette in the comfort of your home, strolling on the beach, at the pub or just when diving? Please get certified in decompression procedures and advanced nitrox.

Have to remember this is the same fellow who considers diving sea caves safe and sees no need for cavern/cave training. Don’t know if he has access to over 40% Nitrox without an Advanced Nitrox or equivalent card.

 

[RayfromTX]

Divers come to scubaboard to learn about diving practices. Often they are smart people that are used to figuring things out on their own and generally getting away with that. Long before my time it was discovered that when new divers came here to ask about basic scuba, we would run them off by attacking them for their ignorance. If we run them off then they can't learn from us. The mods back then decided to try to keep them around long enough to figure out the real deal from those that came before them.

In the advanced forums we have not been so protective of the people seeking knowledge and asking or saying things that sound dangerous or "stupid". Ignorance isn't the same thing as stupid and we really can't help the people we run off. I'm just sayin'.

I learned long ago that asking questions in the advanced and tech forums is asking for several things. I am likely to get:
1 a good answer.
2 a snarky and insulting answer.
3 answers totally unrelated to my question.
4 answers that jump to wrong conclusions and tell me that my gear and instructor is wrong for me.

I see it in thread after thread. Divers come in all excited about starting down a new path. Maybe they are starting a zero to hero course or are wanting to do "light deco" without taking a course. We declare that they must be trolling us, implying that nobody could be this stupid. Maybe they post a video of their training dive with an instructor that they admire and we pick it and their instructor apart. Time after time we run them off. Our members know a tremendous amount about very advanced subjects. It is a shame that some of us are so good at chasing off the audience that needs to learn it.

New to tech is still new. The hide of an alligator shouldn't be required to learn about decompression and redundant systems for staying alive under water.

I am not posting as staff. I am posting as a member and a new tech student. Will I post about my experiences as I take this journey? No

Trust me, in real life I am tough as nails and manage dozens of construction workers every day and I can whither any one of them with a look. I can run them off without even trying. I don't tell them that they are stupid when they do stupid things because I need them, just like we need new divers to stick around. The old ones are hanging up their fins faster than the new ones are catching the bug.

I'm just sayin'

 

[Marie13]

So you’re going to bat for a diver who already had a thread closed down due to unsafe diving practices he advocated and refused to get training for?

Alrighty then.

 

[RayfromTX]

So you’re going to bat for a diver who already had a thread closed down to unsafe diving practices he advocated and refused to get training for?

Alrighty then.

I'm not going to bat for unsafe diving practices but for the members that need a chance to learn that that is what they are.

 

[Diving Dubai]

@60plus

The reason you've got so much push back is because if you had either taken some training or indeed read a good text book, some of the answers would be apparent.

The equipment is pretty simple, Separate redundant bottom gas, and a deco cylinder, all of the appropriate mix for the depth, and containing sufficient gas to meet the acquirement of the run time your consumption rates, teh depth and planned contingent.

If you can't easily work these basics out, then you shouldn't' be contemplating these dives (its all contained within the training)

But theory is one thing

People really do underestimate the practical skills. I'll use buoyancy as a for instance

You should be able to either sense of glance at your computer and then instinctively make adjustments it't shouldn't need thought it should be automatic. Hence if you're deploying a dsmb you should be automatically maintaining your depth without thought - and this applies to all the basic skills Since you need as much free bandwidth as possible

Things do go wrong, either by bad planning, lack of experience or knowledge, complacency or pure bad luck, and you need to resolve the issue there and then.

At depth your cognitive functions decrease, and if you get in a panic you're gas is going to drain at an exponential rate.

In training we can teach the skills, and we can try to put the student under pressure, but because it's considered bad form to bend or kill students, we really can't put them in realistic circumstances.

Trust me a LP hose bursting (or in my case) a reg coming off when deep is a loud noise. But the resolution should be automatic and no more than an annoyance allowing you to solve the issue, re plan on the fly and have bandwidth to mentally berate yourself.

Hence Tech cannot be learnt from books alone, and even when you have taken a course you practice and perfect before attempting deeper longer dives

My strong recommendation to you would be to gain training and then make dives under guidance and supervision and make baby steps,

 

[Soloist]

Divers come to scubaboard to learn about diving practices. Often they are smart people that are used to figuring things out on their own and generally getting away with that. Long before my time it was discovered that when new divers came here to ask about basic scuba, we would run them off by attacking them for their ignorance. If we run them off then they can't learn from us. The mods back then decided to try to keep them around long enough to figure out the real deal from those that came before them.

In the advanced forums we have not been so protective of the people seeking knowledge and asking or saying things that sound dangerous or "stupid". Ignorance isn't the same thing as stupid and we really can't help the people we run off. I'm just sayin'.

I learned long ago that asking questions in the advanced and tech forums is asking for several things. I am likely to get:
1 a good answer.
2 a snarky and insulting answer.
3 answers totally unrelated to my question.
4 answers that jump to wrong conclusions and tell me that my gear and instructor is wrong for me.

I see it in thread after thread. Divers come in all excited about starting down a new path. Maybe they are starting a zero to hero course or are wanting to do "light deco" without taking a course. We declare that they must be trolling us, implying that nobody could be this stupid. Maybe they post a video of their training dive with an instructor that they admire and we pick it and their instructor apart. Time after time we run them off. Our members know a tremendous amount about very advanced subjects. It is a shame that some of us are so good at chasing off the audience that needs to learn it.

New to tech is still new. The hide of an alligator shouldn't be required to learn about decompression and redundant systems for staying alive under water.

I am not posting as staff. I am posting as a member and a new tech student. Will I post about my experiences as I take this journey? No

Trust me, in real life I am tough as nails and manage dozens of construction workers every day and I can whither any one of them with a look. I can run them off without even trying. I don't tell them that they are stupid when they do stupid things because I need them, just like we need new divers to stick around. The old ones are hanging up their fins faster than the new ones are catching the bug.

I'm just sayin'

I adamantly disagree with you in this particular case. The OP either ignores or finds the numerous warnings from experienced technical divers humorous. He has admitted he is untrained, inexperienced and ignorant about decompression procedures and dive planning. The OP justifies and excuses not being properly trained or equipped due to “minimal cost and minimal complication”, his words. Better defined as “cheap and lazy”, my words. If he was genuinely interested in advanced nitrox and dive theory my responses would be totally different, but he is simply trolling for approval for his bizarre mixed gas 50 meter “max bottom time” NDL wreck dive! This individual is a danger to himself, but more importantly to other unsuspecting divers.