DECO the Dark site in recreational Diving

[TSandM]

AJ nailed it.

You are way ahead of most people, by recognizing that having enough gas to do your dive AND your deco is an imperative. Having all that gas dependent on a single first stage is kind of spooky. That's why most people who are doing any kind of diving where the surface is not an option, will use some kind of redundant system, whether it's manifolded doubles, or sidemounted doubles.

But during the time that you are doing that deep dive, and the decompression you have allowed yourself to become OBLIGATED to do, you have to be able to handle any and all issues that come up. Have a freeflow? You need a strategy that doesn't involve surfacing. Lose a fin? Can you manage without one for ten minutes? Lose your mask? Are you comfortable sitting and breathing without it until you have completed your deco -- and does your buddy understand how to help you through this? If you are carrying all your gas on your back, do you know that your buddy has enough for both of you, if your single system fails?

It isn't rocket science, but there is a lot of book learning and a lot of in-water skill building to make mandatory deco safe.

 

[Dr. Lecter]

So let see if I understood, if your regulator and your octo go bad as well, and you have only one one tank (normally recreation setup ), beeing TEC certified will not get you bend ??? Don't think so.

The point was that someone with a basic understanding of reality and what entering deco means (tech trained or not) wouldn't enter deco with a single gas source. If you think it's just fine because you have plenty of air, your reg and tank are reliable, and you're only into deco a little bit...that's cool by me. I could not possibly care less about how a stranger on the internet dives, or what the outcome of their dive is.

You asked for polite information and you got it. Now you're either trolling or telling us why you're a special snowflake exception to the rules. Regardless of which it is, I'm not debating it with you further.

 

[PfcAJ]

I see that I made a mistake in my OP regarding depth, because I did not mentioned and it lead to confusion, I'm just staying in the 35m range

And the event all that you mention happen together, it is just your day to be fish food not even TEC courses will safe you from all that

So let see if I understood, if your regulator and your octo go bad as well, and you have only one one tank (normally recreation setup ), beeing TEC certified will not get you bend ??? Don't think so.

Another mistake of my part, is that I didn't mention that I dive with a watch as well for timing backup, in case my DC take a dump.

if your DC go bad, and you know the dive tables and have watch, and know at what depts to stop and for how long and you just put an extra time at that dept because you didn't take a look for 2min before you notice the DC went sought on you, plus you put another extra time at your second stop, is there something they teach wrong in OW and AOW regarding the tables and the stops.

I know I have enough air because I know the times requiered in the dive tables, and my DC does the safety stops and the same depths sometimes deeper sometimes not so deep, in two oportunities the DC told me to do safety stops at 13m depth and the regular 5m depth, both same time 3min and 2min "in those dives" ( I know it can be different depending ) ended up with 1300 and 1200psi respectively, 60min and 45min dives, depths between 25 and 35m, and looking at the tables the DECO times were very similar, so I Know I have enough air if sh.. don't hit the fan, I can see the confusion I created by not mentioning the depths that I normally are in to.

I know TEC dive have to do as well with redundancy, more than one tank, 1set of regulators per tanks and more redundant things, and a lot of more calculations, gas mixes and knowledge that is not presented on the recreational levels.

Again I know the dangers of the DCS, it was mention many times during my courses, and to stay inside my NDL and why.

Sorry for my mistake I assumed wrong that if I mentioned AOW it was pointing out to not get beyond the 35m , with the following conditions, one tank of air, knowing the dive tables and time tracking and depth, and knowing I have enough air to do my DECO stops.

I can see were I created the confusion my appologies, not that all know the conditions in which I dive, tropical waters, no currents, and the othet things I already mention, am I still not suited to do a DECO dive under normal circumstances ???

My point is that tech diving with a single tank is a bad idea. All your eggs are in one basket.

If your computer breaks, how do you know what depth you're at through the ascent?

You're apparently intuiting your gas requirements. Lets play a game: Tell me how many cubic feet of gas you need to complete an ascent from 100ft (30m) with a stressed SAC rate and a 10min deco obligation. Work it out based on what you know now. No cheating and looking up how to do it. Now tell me how much gas you need if your BT is extended by 5mins. How much does your deco obligation increase? Are you reliant on your computer to tell you that?

All those things you list that are not presented in recreational classes is because decompression diving is beyond the purview of recreational courses. Sry m8.

 

[NAM001]

I like this thread, It is very common thought process for many new ow's. First you say you want to stay down longer and not waste a partial tank because of the imposed NDL. You can control this.. Its done via NITROX. go to a 32% mix and you should accomplish what you want, as i understand the question.

As deco goes. well you either deliberately do it or you just find your self there because you did not pay attention. Not being mean , just honest. for those unplanned events where you find your self on the wrong side of the NDL clock. your dive tables cover that. 5 min over and you stop at 20 ft for x minutes ect. For the deliberate deco dives odds are you will not be covered by the table you were given in ow class. Along with deco comes a whole world of gasses, mostoften in double tanks, that will make your air or nitrox table usless. (gotta love computers), I say this because if you plan on doing deco you are probably not using air or straight nitrox blends. Deco is not dfficult, just unforgiving, but it takes understanding and and a level of respect and a lot of planning since planned deco probably will involve back gas deco gas staged gasses ect. Unfortunately I cant give you a hard fast answer. There are many articles on the physics of gas onloading and off gasseing. saturation, supersaturation and then that other term that is on the opposite end of the saturation specturm. The game is controlling how fast you off gas the saturated gasses, o2, n2, he. Fortunately for the rec diver a lot of conservitism is built in to the table and use of it so there should not ever be a panic when the clock says you are in deco. Most cases the problem is cleared by the time you get to safety stop so long as you ascend slowly. All dives are deco dives. Recreational dives are deco dives that allows deco to be completed via a normal slow ascent. beyond that the process needs some help and that is where the training comes in to play. I would recommend you get into nitrox and spend some time pondering the it and then move on to recreational trimix and deco. This is an area that is worth the time to take time.

 

[LeadTurn_SD]

.... I can see were I created the confusion my appologies, now that all know the conditions in which I dive, tropical waters, no currents, and the othet things I already mention, am I still not suited to do a DECO dive under normal circumstances ???

Again, I'm answering as a "Sport Diver", tropical water, no current, etc. But my long-ago history includes staged deco dives on air.

What everyone here is trying to tell you is that there is a real risk to incurring a mandatory deco obligation if you are not properly prepared.

Being properly prepared includes not only having enough breathing gas to complete the mandatory decompression, but the ability to complete the decompression if something goes a little bit wrong.

PfcAJ gave you a partial list of examples.

Dr. Lecter gave you an actual example of an incident that happened to him.

My own history with deco diving is totally uneventful, but I gave you an example of a friend who made one mistake, and was crippled for life.

Again, we are just trying to caution you to move forward carefully, and only after learning more; and ScubaBoard is not an adequate resource for all the things you need to learn.

Best wishes.

 

[dumpsterDiver]

I see that I made a mistake in my OP regarding depth, because I did not mentioned and it lead to confusion, I'm just staying in the 35m range

And the event all that you mention happen together, it is just your day to be fish food not even TEC courses will safe you from all that

So let see if I understood, if your regulator and your octo go bad as well, and you have only one one tank (normally recreation setup ), beeing TEC certified will not get you bend ??? Don't think so.

Another mistake of my part, is that I didn't mention that I dive with a watch as well for timing backup, in case my DC take a dump.

if your DC go bad, and you know the dive tables and have watch, and know at what depts to stop and for how long and you just put an extra time at that dept because you didn't take a look for 2min before you notice the DC went sought on you, plus you put another extra time at your second stop, is there something they teach wrong in OW and AOW regarding the tables and the stops.

I know I have enough air because I know the times requiered in the dive tables, and my DC does the safety stops and the same depths sometimes deeper sometimes not so deep, in two oportunities the DC told me to do safety stops at 13m depth and the regular 5m depth, both same time 3min and 2min "in those dives" ( I know it can be different depending ) ended up with 1300 and 1200psi respectively, 60min and 45min dives, depths between 25 and 35m, and looking at the tables the DECO times were very similar, so I Know I have enough air if sh.. don't hit the fan, I can see the confusion I created by not mentioning the depths that I normally are in to.

I know TEC dive have to do as well with redundancy, more than one tank, 1set of regulators per tanks and more redundant things, and a lot of more calculations, gas mixes and knowledge that is not presented on the recreational levels.

Again I know the dangers of the DCS, it was mention many times during my courses, and to stay inside my NDL and why.

Sorry for my mistake I assumed wrong that if I mentioned AOW it was pointing out to not get beyond the 35m , with the following conditions, one tank of air, knowing the dive tables and time tracking and depth, and knowing I have enough air to do my DECO stops.

I can see were I created the confusion my appologies, now that all know the conditions in which I dive, tropical waters, no currents, and the othet things I already mention, am I still not suited to do a DECO dive under normal circumstances ???

If everything works, doing some deco is not hard. It is easy, it is simple, in reality it is no harder than doing a normal safety stop that every recreational diver can do. If you want to follow your computer, make sure you have enough air and keep your deco to a moderate amount, then you can EASILY do deco dives on a single tank of air or nitrox. Don't let ANYONE tell you differently.

However, if your profile is correct and you have 25 dives or something, you have probably never seen any accidents, problems, failures, serious screw ups .... so all of this "dangerous" talk sounds theoretical.

In reality, if you engage in diving for a while, there will be incidents and accidents and little failures here and there, even big failures, but MOST (not all) of them can be "handled" with the right equipment, skills and knowledge. With 25 dives and a single tank, you have NONE of these tools to survive a problem.

 

[Remy B.]

The point was that someone with a basic understanding of reality and what entering deco means (tech trained or not) wouldn't enter deco with a single gas source. If you think it's just fine because you have plenty of air, your reg and tank are reliable, and you're only into deco a little bit...that's cool by me. I could not possibly care less about how a stranger on the internet dives, or what the outcome of their dive is.

You asked for polite information and you got it. Now you're either trolling or telling us why you're a special snowflake exception to the rules. Regardless of which it is, I'm not debating it with you further.

My appologies Dr. LECTER, you are right I should have answered like that, no I'm not above any one, no I'm not a super dupper diving, yes I know it is not safe, I didn't say it was, I'm aware of the dangers.

---------- Post added October 2nd, 2014 at 12:28 AM ----------

Thanks, for your answers guys, all good ones and taken, specially the answer from KWS, that put my mind set.

Yes not dought about it I need training never see me without training, and always driving my self to get there when time and money allows it.

My worst fear is that I loose my mask, no good at all, since you can't read no press gauge, no depth gauge, no DC, no watch for time trancking, even If I can count on my dive buddy, I still don't take it for granted.

Will go after the Nitrox, I have encounter some opinions regarding nitrox and depth limitations, but I will ask for sure in the class room in read the books, to get the complete grasp of the Nitrox, kind of confusing to me that as well I see Tec Nitrox in some course listing

Please continue with your interventions, more perspectives and experiences you tell me it just let me understand more and be more prepared for the glass rooms, and better questions I can formulate.

 

[tech_diver]

Today, we are very fortunate that a diver like yourself who wants to do more advanced diving has books, resources and instructors available. There was a time when there weren't a lot of tech instructors and deco diving was talked about in whispers. Now there are civilian agencies that train at the most advanced levels of scuba diving. Scubaboard can be a great source of info but it can't replace actual training.

If you have a sincere passion and drive to expand your diving, do as much scuba diving, scuba reading and scuba training as you can.

But do beware, it looks easy. You see a diver doing a deco dive comfortably but you may not notice all the details, like the backup mask in his thigh pocket. You certainly can't see all the training and experience he is carrying. A deco dive has a lot of moving parts that you have to know intimately.

 

[shoredivr]

Hi Remy, try these guys: https://m.facebook.com/TecDivingCuracao?_rdr

Beautiful diving in dushi Curaçao. Good to have these questions about deco. I prefer having redundant tanks - sidemount - or a single back mount with a slung tank for redundancy when doing deco.

 

[Edward3c]

As you see I'm a rucky diver, but I like to learn with good facts and opinions and rational , positive and educated answers, and polite answers, if any feel that this is not possible, you are egocentric or you find just a stupid post, please ignore this post, I don't need a negative or troll answer, I'm here for the positive learning in educated interaction, I'm kind of expectiving negative comments but please address them in good manners.

I always been attracted by the underwater world so I make one of my goals to become true, and I experienced diving and got certified, OW + AOW, great instructors, great great experince.

During both of my courses dive tables were addressed.

But the message behind the learning was keep it recreational diving the moment you want to get in DECO it stops been recreational, kind of a bad mojo type thing.

Unfortunadly I'm more curious on what is deeper down, I do enjoy watch fish but at the end they are what they are and I like structures, wrecks normally they are deeper, but I really like to take my time to observe, and I'm limited by the DC Alarm telling me you are 4 min from DECO and it gets more pushy whe I get the 2 min from DECO, I always keeping an eye on my air press but I make good ( or maybe bad ) use of my air and end up with I believe enough air at the end of the dive always above the 1000psi, the last 4 dives my instructors hit the 1/2 tank rule before me.

I know I can stay longer down deep and enter DECO and still have enough air, yes I know you will always want to have enough air reserve in case something go south on you, but now days dive equipment is more safer and actually it appear it can't get beyond what your 1st and 2nd stage regulators are safe wise, there is no improvements further to be done from what already exist exept of creating a complete new different setup.

With that mention, I agree yes still something can get wrong, in if sh... hits the fan while in DECO the chances are bigger to get hurt or be fish food.

But why I should get in DECO to stay a little longer down deep, knowing I still will have enough air at the end of the dive, I just find limiting the time you can enjoy down there by the DECO.

I see my self getting into TEC diving just to spent more time deep down, if money wise I'm ablento go that direction.

I have saw comments here in SB about you need to be certified or trained to do DECO, I'm not saying there is nothing to learn additionaly, but are not the famous Dive Tables already tell you as well as your DC how much time you need to DECOpress and all the teaching in OW and AOW about the DECO and the safety aspect as well as the negatives of not do one.

I have the impresion ( maybe wrong ) that DECO is a bad thing to do or only allowed by TEC, but if I have enough air to spend 10 more minutes down there, why I should not do that, I'm not looking to make a rutine of doing so just to be clear.

Thanks for your light in this, hope comments and opinions are plased in profesional and educated manner.

The move to teaching deco diving is a money cow for the majority of agencies. In the UK BSAC have always included how to dive with decompression stops; its not rocket science.

Adding an extra 10 minutes of bottom time at:
* 35m will give you about 3 minutes of deco at 6m.
* 30m will give you about 3 minutes of deco at 6m.
* 25m will give you about 1 minutes of deco at 6m.
* 20m will give you about 1 minutes of deco at 6m.

This is based on BSAC 88 Tables; other tables will give difference numbers, but they won't be that far out.

Your need to calculate the extra gas requirements for each dive, and what bailout you want, if any.

Kind regards