Equipment for Adv Nitrox and Deco Proc

[grazie42]

I sort of agree with DA Aquamaster...it´s an "easy out" for instructors who want to taskload students and I definetly agree that training should be governed by a "train like you fight, fight like you train" mentality...

The hardest drill I´ve ever had to do was "unconscious diver lift" with simulated deco obligation in open ocean...by the end of that I was literally done for the day...not just the "skill issues" of trying to get someone to the surface but also the thinking and judgements you need to make during the ascent..."should I pause to shoot an smb? or two?", do I cut/ignore my deco?, how the **** do I control bouyancy, depth and time while keeping airway open? gas-switches? do I just send him up?...

I can´t think of anything more stressful...and in the drill, the "drill part" is quite quickly forgotten...the discussions afterwards were very interesting too...

 

[David P]

Im currently in NAUI ADV/Deco/Triox, we students mostly all dive the same way (mostly all GUE trained) with the same gear. We all have drysuits, doubles, can light, smb (some loaded some not loaded) spool, reel, we all have 40' deco bottle, though we just found out we need 2 of them. As far as I know (about half the class is serious, half show up whenever) we all can hover just off of the bottom, do valve drills, shoot a bag, share air...blah blah blah. We were told that we need to demonstrate the use of a 50lb bag as a backup buoyancy device, I said, "I have a drysuit" the instructor kinda rolled his eyes "I know, rules say you need a bag but dont worry, I will supply the bag, you guys don't need to buy one" I don't think everyone has a backup timer, or two BU lights. Those things are kinda small fries compared to the skills we need to have. The lights...ehh the timer, your backup is your team...

 

[String]

your backup is your team...

Thats a philosophy i strongly disagree with in ALL diving and the more advanced it gets the more dangerous i think that is.

Everyone should be entirely self sufficient and equipped so that they can get themselves out of a situation without having to rely on 3rd parties.

 

[AbyssalPlains]

I'm also taking an Advanved Nitrox/Deco Procedures class right now and have followed this thread with great interest. I'm in a similar position as the OP (don't live near the ocean, not sure if owning a twinset any time soon), but my motivation is to become a better diver and I still haven't given up on the hope of doing deco diving on large singles and a 40 cu ft stage bottle. I have no intrinsic issue with doubles (contrary to what my avatar suggests ;-) but am doubtful as to what the actual chances are for renting them at the destinations I fly to. The general question that popped up in my head while reading this thread was, Why not doing deco diving with a single Al 80 on the back and another Al 80 slung?

 

[Bismark]

I'm also taking an Advanved Nitrox/Deco Procedures class right now and have followed this thread with great interest. I'm in a similar position as the OP (don't live near the ocean, not sure if owning a twinset any time soon), but my motivation is to become a better diver and I still haven't given up on the hope of doing deco diving on large singles and a 40 cu ft stage bottle. I have no intrinsic issue with doubles (contrary to what my avatar suggests ;-) but am doubtful as to what the actual chances are for renting them at the destinations I fly to. The general question that popped up in my head while reading this thread was, Why not doing deco diving with a single Al 80 on the back and another Al 80 slung?

It might be interesting to work through a few dive profiles that result in you having a decompression obligation and see how a large single tank stacks up. Since you are taking a deco course right now, why not lets do this and see what comes up? I always think working through a question and coming up with an answer is a better learning exercise than is simply having someone give you an answer. I would suggest though that we be specific about the parameters of the dive at the outset and include everything that may or may not be assumed. (eg: diving with a buddy or not?, Warm water or not? Exposure protection type?) Etc. All these things will have a bearing on the solution to your questions. Usually, the best answer to a question presents itself rather easily. Want to give it a try? This could be a good learning process for other readers as well.

 

[Divin'Papaw]

I'm also taking an Advanved Nitrox/Deco Procedures class right now and have followed this thread with great interest. I'm in a similar position as the OP (don't live near the ocean, not sure if owning a twinset any time soon), but my motivation is to become a better diver and I still haven't given up on the hope of doing deco diving on large singles and a 40 cu ft stage bottle. I have no intrinsic issue with doubles (contrary to what my avatar suggests ;-) but am doubtful as to what the actual chances are for renting them at the destinations I fly to. The general question that popped up in my head while reading this thread was, Why not doing deco diving with a single Al 80 on the back and another Al 80 slung?

1. Complexity of gas management and the task loading of switching regs at key waypoints. Handled safely by sidemount divers, so clearly doable.
2. Difficulty of maintaining trim with a small tank on your back and the same size tank hanging at your side. Seems like it would be awkward.
3. If you have a major first or 2nd stage problem, you just lost half of your gas supply.

 

[AbyssalPlains]

1. Complexity of gas management and the task loading of switching regs at key waypoints. Handled safely by sidemount divers, so clearly doable.
2. Difficulty of maintaining trim with a small tank on your back and the same size tank hanging at your side. Seems like it would be awkward.
3. If you have a major first or 2nd stage problem, you just lost half of your gas supply.

All very good points. But what about #3: How would that be any different with doubles?

 

[AbyssalPlains]

Bismark wrote:
It might be interesting to work through a few dive profiles that result in you having a decompression obligation and see how a large single tank stacks up. Since you are taking a deco course right now, why not lets do this and see what comes up? I always think working through a question and coming up with an answer is a better learning exercise than is simply having someone give you an answer. I would suggest though that we be specific about the parameters of the dive at the outset and include everything that may or may not be assumed. (eg: diving with a buddy or not?, Warm water or not? Exposure protection type?) Etc. All these things will have a bearing on the solution to your questions. Usually, the best answer to a question presents itself rather easily. Want to give it a try? This could be a good learning process for other readers as well.

Great suggestion. Let's go. What do you want me to do?

 

[Bismark]

Bismark wrote:
It might be interesting to work through a few dive profiles that result in you having a decompression obligation and see how a large single tank stacks up. Since you are taking a deco course right now, why not lets do this and see what comes up? I always think working through a question and coming up with an answer is a better learning exercise than is simply having someone give you an answer. I would suggest though that we be specific about the parameters of the dive at the outset and include everything that may or may not be assumed. (eg: diving with a buddy or not?, Warm water or not? Exposure protection type?) Etc. All these things will have a bearing on the solution to your questions. Usually, the best answer to a question presents itself rather easily. Want to give it a try? This could be a good learning process for other readers as well.

Great suggestion. Let's go. What do you want me to do?

Start by stating the dive profile you want to do in terms of depth and time and gases used, etc. Also include such incidentals as water temp (warm water or cold water) exposure protection, tank size, experience, etc. All the things that are considered in planning a dive but which you might just assume based on your past diving. We don't know each other so don't assume I know anything about what you are planning. You would be surprised at how small things you take for granted are things that could affect the answer to your questions.

 

[Divin'Papaw]

All very good points. But what about #3: How would that be any different with doubles?

With doubles with an isolation manifold you can shut down the left or right post and still have full access to both tanks. It's only in the event you have a tank valve issue (burst disk or tank o-ring typically) that you have to isolate. Only then do you lose half of your gas.