Decompression Course

[DevonDiver]

PADI Tec40 - 10min (max) non-accelerated deco to 40m, using 50% (for conservatism only)

PADI Tec45 - unlimited, accelerated deco to 45, using >100% (single deco gas only)The first step (40) is easy...gets you in the gear, gets you planning dives properly, teaches you mindset, gets you precise and introduces you to tech-level performance standards; especially with fundamental skills (buoyancy, trim, awareness etc). 10 minutes of non-accelerated deco, off-set by using 50% on ascent keeps you very safe if you messed up (N2 on surfacing is likely to be much less than an aggressively planned no-stop dive).

Using nitrox as a bottom gas, with that 10 minutes of deco extra, on a dive computer, with doubles... gives you substantial increases in bottom time compared with recreational deep divers. But gives you much more safety (redundancy, known emergency protocols, planned diving, increased off-gassing) when diving at those depths.

Compare the Tec40 to the Deep Diver course: PADI Deep Diver Course Versus Tec40 - A comparison in training

The next step (45) ups the challenge... this is 'real' technical diving, even restricted to 45m (recommended limit post-training) you can obligate a lot of accelerated deco and get yourself in significant trouble...

Rec TRIMIX - is going to primarily be recommended by divers with experience in the western (1st/developed) world. USA divers in particular... who have ample access to relatively cheap helium. It's also more beneficial to them, due to demanding diving conditions... and potential impact on narcosis. Living in a tropical, warm-water environment, where helium costs a fortune and is often unavailable completely... I simply find little argument for normoxic trimix on open water (non-overhead) dives.

The combination AN/DP course from TDI only requires 6 dives, only two of which must be deeper than 100 feet, can be done in 2 (long) days (but three is better), and qualifies you to 45m. It is kind of the sweet-spot in technical training.

I fail to see how 'shorter is better'. 6 dives to provide 45m accelerated deco with 2 deco mix seems a very, very bare minimum.

Tec40 & Tec45 give the same (but one deco gas)...and is 8 dives minimum. Even then, I find a lot of students require supplementary dives to make the grade. I just suppose it depends on where the individual instructor makes the grade.... hmmmm

Too many people focus on how much a given course qualifies you to do.... rather than what is important; how much training and experience it gives you, relative to the diving level certified.

In technical diving, where the risk levels rise dramatically compared with recreational diving, hunting for the most 'bang for the bucks' certification card can be a foolish strategy. Less is NOT more.

Card collecting, zero-to-hero and instant gratification are the antithesis of the technical diving mindset.

Stating, as a positive point, how little technical training you can do, to get the card that allows you to do the most, most unforgiving, diving.... is absurd.

I personally like the PADI technical system because it offers a logical progression in risk versus training/experience. Tec40 gets you in the gear, with the knowledge and protocols and mindset... but keeps you insulated from punishment if you mess up. It lets you practice 'technical approach' diving, but with little more risk that a recreational diver should something go wrong that you're not yet sufficiently skilled or experienced to cope with. That is very wise.

Tec45 raises the stakes somewhat... but you've been given chance to raise your game to meet those risks.

Tec50 does little more than introduce the use of more (2+) deco gasses... mistakes in multi-gas mix deco being the single biggest killer of tech divers... so it is a logical thing to withhold until greater experience is gain...and consequently reduced stress/task-loading on dives.

I did my adv rec trimix and it was a peice of cake....Toughest skill was changing the computer over....

I always felt the best thing about the technical courses I did was that they were enormously challenging... even humbling. That's the feedback I get from my student's too...and other competent technical divers.

 

[KenGordon]

I am sure that TDI Advanced Nitrox/Deco Procedures is only one deco gas. You can also add on Helitrox (sp?) for mild trimix. My course was four hard days and we all deservedly failed, mostly due to poor team skills.

 

[Pullmyfinger]

I fully agree with Mike and Jim about getting lots of experience diving with twins before taking a tech class. I had not used twins in over a decade and for the past 200 dives in a tropical setting, I used a simple back inflate BCD (please, no comment). My first week on twins were not pretty. It took some time to develop good trim/buoyance and develop new muscle memory for BP/W and twins. I would not start tech course until you feel really stable and comfortable with twins.

I agree with this also.
I spent some time diving doubles on easy recreational dives, just getting used to diving them.

Taking a technical diving course brings with it a pretty big commitment in terms of buying gear. I discussed with my TDI Instructor well in advance of my AN/DP course about the equipment requirement.

The jump from recreational diving (the gear) to technical diving (much more/different gear) is pretty significant.

It would be difficult to begin you course with no experience diving doubles. I would recommend buying the required gear, and just diving doubles on some easy dives. Allow yourself some time to get used to the new rig.

---------- Post added July 28th, 2014 at 10:57 PM ----------

I am sure that TDI Advanced Nitrox/Deco Procedures is only one deco gas. You can also add on Helitrox (sp?) for mild trimix. My course was four hard days and we all deservedly failed, mostly due to poor team skills.

Mine was with two deco gasses. The days were definitely challenging.....we had to repeat some dives due to having to un-f*** ourselves.

 

[NL1983]

Hi All,

Again thanks for the ongoing advise, tips, comments and more.

My idea is not to go "fully into tech" I am enjoying myself more than enough (at least for the moment) at anywhere between 0-40 meters. The only issue I have with Rangiroa is that from what I read the interesting bit of the Tiputa pass is deep and you want to spend most of your time there. The only way to do that (and following the rules) is to be deco certified and potentially get certification for a couple of meters extra. I would likely not be using the certification often afterwards.

I am not a big fan of two tanks on my back, side-mount would be a much better option as I found that quite comfortable. On the other hand I have not dived side-mount in strong current.

Depth
One of the dive-centers had the following on their website, so I guess the depth part is less of an issue:

"The equivalence principle implies that all level 1 and level 2 certifications from any other school will be considered as level 1 CMAS and that divers can get assistance down to a maximum depth of 95 feet – for instance, an Open Water PADI certificate and an Advanced Open Water PADI certificate will be considered as equivalent regarding the maximum depth.
Level 3 and level 4 certificates other than the CMAS ones will be considered as a level 2 CMAS certificate and divers can get assistance down to a depth of 160 feet.

For any other certificate, the maximum depth will necessarily be 197 feet."

Deco
The same center had the following as part of one of their dive-site description, that sounds like it is quite common to do decompression dives:
"Towards the end of the diving we will slither in the calm waters of the lagoon in which we will decompress slowly and in all safety."

Finding out more information
As a couple of people mentioned it all depends on what the dive-centers offer and require. I have e-mailed a couple and am waiting for their responses. It does seem difficult however to get anything organized beyond nitrox. I am not even sure about double tank dives or side-mount if you don't have the equipment yourself.

I will do a bit more background reading on the courses you all suggested and when I hear back from some of the dive-centers I will let you know as well.

Thank you for the ongoing tip and tricks

 

[boulderjohn]

Hi All,

Again thanks for the ongoing advise, tips, comments and more.

My idea is not to go "fully into tech" I am enjoying myself more than enough (at least for the moment) at anywhere between 0-40 meters. The only issue I have with Rangiroa is that from what I read the interesting bit of the Tiputa pass is deep and you want to spend most of your time there. The only way to do that (and following the rules) is to be deco certified and potentially get certification for a couple of meters extra. I would likely not be using the certification often afterwards.

I am not a big fan of two tanks on my back, side-mount would be a much better option as I found that quite comfortable. On the other hand I have not dived side-mount in strong current.

Depth
One of the dive-centers had the following on their website, so I guess the depth part is less of an issue:

"The equivalence principle implies that all level 1 and level 2 certifications from any other school will be considered as level 1 CMAS and that divers can get assistance down to a maximum depth of 95 feet – for instance, an Open Water PADI certificate and an Advanced Open Water PADI certificate will be considered as equivalent regarding the maximum depth.
Level 3 and level 4 certificates other than the CMAS ones will be considered as a level 2 CMAS certificate and divers can get assistance down to a depth of 160 feet.

For any other certificate, the maximum depth will necessarily be 197 feet."

Deco
The same center had the following as part of one of their dive-site description, that sounds like it is quite common to do decompression dives:
"Towards the end of the diving we will slither in the calm waters of the lagoon in which we will decompress slowly and in all safety."

Finding out more information
As a couple of people mentioned it all depends on what the dive-centers offer and require. I have e-mailed a couple and am waiting for their responses. It does seem difficult however to get anything organized beyond nitrox. I am not even sure about double tank dives or side-mount if you don't have the equipment yourself.

I will do a bit more background reading on the courses you all suggested and when I hear back from some of the dive-centers I will let you know as well.

Thank you for the ongoing tip and tricks

I am really having a hard time understanding the situation, and I think it would be a good idea to ask for more information from that dive center. I would start by asking exactly what they really mean when they say "Towards the end of the diving we will slither in the calm waters of the lagoon in which we will decompress slowly and in all safety." How much decompression are they talking about? Is it true decompression, or are they talking about safety stops?

Decompression certification is a major process--there is no "deco-lite just for one trip" certification that I know of. Why is that? It is because the difference between NDL diving (OK, things just went bad--I'd better get to the surface) and true deco diving (OK, things just went bad--I'd better use my training and my specialized equipment to solve this problem where I am, since I can't go to the surface) is huge.

Now--are there people do deco diving without the certification by just following their recreational computers and without redundant gases? Yes, there are. Are there operations that allow and even encourage it? Yes, there are.

You have to make your own decisions about that, and to do so, you need more information about what you are getting into than I see here.

 

[Nirvana]

I think that the only reason for doing a technical course is having interest in going forward with it after certification. If you don't want to do deep (>40m), deco, cave or wreck penetration dives, it would be a huge waste of time and effort. Of course, you may just take it for the knowledge and basic skills, but I think both can be worked out very well outside of a tech course.

For one trip, or worse, a few deep (~40m) dives in a trip, I think I'd prefer to ask for a 15l cylinder and dive within NDL.

 

[DuboisP]

Well, while trimix certainly has it's uses, I think that the OP wants to do tech for the same reason that I wanted to do it. We have a lot of great wrecks in my area (NYC) in the 100-140 foot range. So while I have been doing these without deco, it gets old fast getting up extremely early (or staying over on the boat), driving an hour to the dock, and spending the day at sea for two 18 minute dives. I wanted to be able to spend more time at these depths, and I don't think that trimix is worth the expense in that range.

I have never really felt the effects of narcosis down to the 140 feet. I realize that different people have different susceptibility to this, but my instructor feels that nitrogen narcosis effects at these depths is probably overrated and CO2 retention effects are underappreciated. While I'm not denying the role of trimix, it seems that it wouldn't be necessary for me (or for the OP).

in France, divers are trained to decompression at level 2 (a little more an AOWD).
At level 3, we're trained to go to 200 feet on air.
I dive regurlarly to 160 feet on air. depending the visibility without no narcosis.
i'am also nitrox advanced and trimix diver, and, as i'm 57 old, i bring a rich nitrox (80%) or oxy pony for deco, that's better.

---------- Post added August 2nd, 2014 at 08:50 AM ----------

I am really having a hard time understanding the situation, and I think it would be a good idea to ask for more information from that dive center. I would start by asking exactly what they really mean when they say "Towards the end of the diving we will slither in the calm waters of the lagoon in which we will decompress slowly and in all safety." How much decompression are they talking about? Is it true decompression, or are they talking about safety stops?

that's true decompression.
you dive to 160 feet, enter in deco, ascend slowly, reduce deco time, and end by looking fishes at less than 20 feet.
an usual dive according our standards :cool2:

trimix is very expensive in these islands, as tanks came by boat.

 

[mathauck0814]

My idea is not to go "fully into tech" I am enjoying myself more than enough (at least for the moment) at anywhere between 0-40 meters. The only issue I have with Rangiroa is that from what I read the interesting bit of the Tiputa pass is deep and you want to spend most of your time there. The only way to do that (and following the rules) is to be deco certified and potentially get certification for a couple of meters extra. I would likely not be using the certification often afterwards.

As they say, one cannot be "a little bit pregnant". Decompression diving is "fully into tech"nical diving. You will need more than one source of gas and you will need training that is not going to resemble any course you've taken thus far in your diving career. Technical diving (least of all Intro to Tech courses) are an order of magnitude more indepth and challenging (and incur a far higher failure rate) than any PADI specialty you've experienced.

I am not a big fan of two tanks on my back, side-mount would be a much better option as I found that quite comfortable. On the other hand I have not dived side-mount in strong current.

You may want to reconsider this trip or delay it until you are qualified to perform the required skills to do the dives you're interested in.

One of the dive-centers had the following on their website, so I guess the depth part is less of an issue:

"The equivalence principle implies that all level 1 and level 2 certifications from any other school will be considered as level 1 CMAS and that divers can get assistance down to a maximum depth of 95 feet – for instance, an Open Water PADI certificate and an Advanced Open Water PADI certificate will be considered as equivalent regarding the maximum depth.
Level 3 and level 4 certificates other than the CMAS ones will be considered as a level 2 CMAS certificate and divers can get assistance down to a depth of 160 feet.

For any other certificate, the maximum depth will necessarily be 197 feet."

I'm reading this as a limitation on the type of gas they can provide (namely, not trimix).

The same center had the following as part of one of their dive-site description, that sounds like it is quite common to do decompression dives:
"Towards the end of the diving we will slither in the calm waters of the lagoon in which we will decompress slowly and in all safety."

Decompression is fairly easy and straightforward when it goes well. When it goes T.U. it can end very poorly for you if you're untrained and underequipped. The south pacific is notorious for putting folks into bad spots with insufficient gas and gear (Truk, Bikini, etc). Just because it can be gotten away with doesn't make it safe.

As a couple of people mentioned it all depends on what the dive-centers offer and require. I have e-mailed a couple and am waiting for their responses. It does seem difficult however to get anything organized beyond nitrox. I am not even sure about double tank dives or side-mount if you don't have the equipment yourself.

Well, you're not going to be bringing tanks, so at the very least they'll need to provide you a twinset or independent tanks for side mount (you'll have to bring your own stage kits, etc). Do you have a bp/w? a doubles wing? a sidemount kit? sidemount or deco regulators? stage rigging? etc. All things you would need to complete these dives (and all of which you'd need to be prepared to bring with you if the resort cannot provide it).

Thank you for the ongoing tip and tricks

No tricks here. The tip is to get formal technical dive training and do dives properly.

 

[OMANDIVER]

All dives are decompression dives. Sounds from where you are going and that the depth you are considering that helium is a luxury you may not need. The light trimix certs only give you the depth rating to say 48m(iantd) if you use the trimix not on air, then its only 42m. My opinion is only do a tech course to say 45 m (TDI AN/DP sounds useful for what you want, is only one course in reality and is geared towards using V planner) if you can do it there and then do some fun dives with the same instructor. If you do a course somewhere else your guide may insist you spend the first half to one day checking you out in shallow water. Plus you will spend a whole load of time trying to sort equipment out. Really not worth it. I would either decide to start to learn technical diving or have a fun holiday. Only combine the two if you can do it there with an instructor with a good reputation and who you trust. My tuppence worth.

 

[Nasser]

You can't get around diving physics. If you want to dive deeper or stay down longer beyond NDL limits then you will absorb more nitrogen, use more gas, and you will have to perform mandatory deco stops. The line between NDL and Deco Stop diving - as has been mentioned - is substantial and there's no way around this... if you want to significantly extend your bottom time / depth beyond recreational limits and do this safely, then you need to get the proper training and equipment.

Either dive within NDL or get the proper technical training or choose different sites.