Dive tables for accelerated decompression

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

What the OP is looking at is tech diving but on the cheap. Using a second gas mix for decompression is something I wouldn't want to rush into and I would suggest others not do it either.

For extended duration dives beyond NDL, you should be looking at a minimum of a twinset to give suffiicient gas (especially at the depths you are looking at) as well as carrying a minimum of one deco stage tank. Learning how to use the twinset safely (doing shutdowns etc) AND making safe switches to your deco gas while holding station at a specific depth takes quite a bit of skill and training. You also need the ability to problems solve while at depth as you have no direct safe exit route once you rack up deco - you need to either solve the problem there and then or risk an early ascent and possible serious DCS injury or even death.

If deeper & longer dives are in your plan, take an AN/DP course. It will give the skills you need to stay alive and well.
 
Available for Bar Mitzvahs, Weddings, and Anything

but as the original poster liked one of your posts you may have something.
I have no idea what you are talking about.
Why did you quote me? Who is "your" and "you" in "the original poster liked one of your posts you may have something" and what is "something"

Perhaps being less cutesy and less cryptic might make your posts more intelligible.
 
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.
 
If you have to bail out at 45m you PPO2 on 32% will be 1.8. Are you comfortable with that?
 
The US Navy dive manual has the tables and a pdf can be found with a little googling. BUT be forewarned the navy assumes significant risk with oxygen toxicity and ppO2. I advise taking deco procedures, and advanced nitrox prior to any accelerated deco dives.
 
If you have to bail out at 45m you PPO2 on 32% will be 1.8. Are you comfortable with that?
The standard ppO2 that was once assumed to be the rule for deco in the early tec days was 2.0 for deco. The us military still assumes this ppO2 as well. It’s not ideal, but if you pay attention to your oxygen loading and are in an oh **** situation the risk can be assumed
 
If you have to bail out at 45m you PPO2 on 32% will be 1.8. Are you comfortable with that?
If you are on air at 45m there is a good chance you'll be so narced you won't notice or care what the PPO2 is, if you can even bail out.
 
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 ADP Accelerated Decompression Procedures (ADP)

It has multi gas tables (mentioned above) so you can do down to air and 50%. They might be a bit aggressive when compared to current fashion though.

You’re plan here of using a single and 32% isn’t really better than indie twins of 25%, it might save 15 minutes on a 90 minute runtime. Using 80% cuts that to 60 minutes.

You can download demo versions of MultiDeco etc which will let you play ‘what if’.

At those depths the you want proper redundancy. A pony will not be enough. You also have to consider what happens if you loose the deco gas. That is the kind of stuff a course will tell you.
 

Back
Top Bottom