Tech expectations

[Bazzathemammoth]

Hi all

Earlier this year I did an intro to tech class (not affiliated with any agency, but a very dir style instructor) and bought a twinset. I could see myself getting into tech eventually, and thought the Twinset would be great for redundancy while solo diving. I’ve found that I’m really enjoying Twinset diving and I’m trying to figure out what to do next.

I did a dive in the weekend on the Rena wreck which is 55m to sand, 30m to most of the wreck, with most of the good stuff in the 35m+ range. We had a short dive to max 38m to check it out. After the dive I had the overwhelming thought that diving within recreational limits is a really lame way to try and get the most out of a trip there.

I’m wondering how much more time I would have around the 40-45m range with an entry level deco course eg paid tech40, tdi andp, or ssi extended range? I think those courses qualify up to 10 mins of decompression on 50%? PADI tec40 is the most limited, but also has the best instructor that I’ve found, being the same guy that did my intro to tech class. Other than 5m less max depth, would there be any other limitations with PADI that I should know about?

I wasn’t planning on going tech so soon, but I’d love to make the most of some of the great diving we have on offer. Tia

 

[inquis]

Padi's Tec40 is actually less limiting. It's basically their version of TDI's Intro to Tech (if you do it in doubles) but also adds limited deco. (TDI's ITT has no deco.)

Typically, TDI does Advanced Nitrox and Deco Procedures combined. Doing that after (or also combined with ITT) gives you single-bottle deco on O2 (equivalent to Tec45). However, since that's 3 TDI courses, the PADI 3-course path is Tec50 which gives 2-bottle deco. (Similar to TDI, you can combine parts of Tec40, 45, & 50.)

Basically, if you feel the instructor is quality, go for it. PADI has a bad rap for tech because of the proportion of quality instructors, but if you find a good one, that point is moot.

 

[inquis]

Check out this thread as well. In particular, @boulderjohn's summary of the "front loading" vs "back-loading" of deco.

 

[boulderjohn]

Typically, TDI does Advanced Nitrox and Deco Procedures combined.

I have taught both programs. TDI's classes are usually taught in combination because taking them in sequence (as I did) makes no sense. PADI's program can now also be taught in combination, and doing so makes more sense for them that way as well. Teaching both programs in their combined forms allows the required dives to be done in a different order, and in both cases the different order is much better than the original design.

 

[Wibble]

I’m wondering how much more time I would have around the 40-45m range with an entry level deco course

Basically it's about managing the one failure. An entry ANDP course will give you a single deco gas with rich nitrox.

Assume the failure happens to the deco gas. Your limit is how much backgas you carry; how much deco would you need to do on the backgas. Solve that calculation for your SAC (gas consumption rate) and you will know how much time you'll get at, say, 40m using 28% in a twinset as your backgas.

Obviously if your deco gas failed, you'd be sharing with a buddy; once they've finished their deco on their deco gas, they'd pass their deco cylinder to you to finish your deco (you'd have been using your backgas in the meantime).

 

[boulderjohn]

I’m wondering how much more time I would have around the 40-45m range

I think it is a failure that agencies do not promote a course for that purpose. Actually, Tech 40 all by itself will be what you want right now, but it is not promoted that way. I know that in some places where I dive there are good dive sites that the operators will not go to because they are not deep enough for the tech divers to get excited about but too deep for NDL divers to get decent bottom time. A certification that allows you to extend your time at sites like that would be ideal. As I wrote above, tech 40 does exactly that, but it is not promoted for that purpose so people do not realize it.

 

[rhwestfall]

TBH, the reason I got my tech certs was to dive in comfort without having the NDL boogeyman chasing me. Getting to swim the whole wreck and really look at it is simply enjoyable.

The stuff I dive is mostly at 110'-120', with deep for me being 130'-160'. Love the bottom time.

 

[VikingDives]

I’m wondering how much more time I would have around the 40-45m range with an entry level deco course eg paid tech40, tdi andp, or ssi extended range?

With ANDP, there's no limit, beyond gas limitations imposed by the course, back gas plus one deco gas. There's no time limit on deco imposed by the course.

 

[Wibble]

I know that in some places where I dive there are good dive sites that the operators will not go to because they are not deep enough for the tech divers to get excited about but too deep for NDL divers to get decent bottom time.

A lot of the English Channel wrecks are like that in the 30m/100ft to 45m/150ft range. Tech divers do those dives, but will be diving much longer bottom times, say a couple of hours dive length, whereas the more recreational divers will be doing shorter dive times.

The initial ANDP (Advanced Nitrox & Deco Procedures) from TDI was a great course for those depths with a single decompression stage cylinder. It can be done with an additional dive for "helitrox" which is (or was) up to 20% helium that isn't overly expensive to reduce the narcosis. OK, helium's much more expensive now.

Although the next course on from ANDP, the Normoxic Trimix course uses two decompression stages and richer mixes. However, it's not the richer mixes which are the main benefit, it's having the two deco stages which means you can do longer decompressions with backup decompression gas. Then a 40m/130ft dive can safely be easily extended to give over an hour of bottom time.


The main point about technical diving is it's a steady progression to develop your competences. Core skills. Redundant gas (twinset/sidemount). Decompression on backgas. Decompression with one richer gas in a stage cylinder. Helium. Decompression with two decompression cylinders....

 

[Angelo Farina]

Hi all

Earlier this year I did an intro to tech class (not affiliated with any agency, but a very dir style instructor) and bought a twinset. I could see myself getting into tech eventually, and thought the Twinset would be great for redundancy while solo diving. I’ve found that I’m really enjoying Twinset diving and I’m trying to figure out what to do next.

I did a dive in the weekend on the Rena wreck which is 55m to sand, 30m to most of the wreck, with most of the good stuff in the 35m+ range. We had a short dive to max 38m to check it out. After the dive I had the overwhelming thought that diving within recreational limits is a really lame way to try and get the most out of a trip there.

I’m wondering how much more time I would have around the 40-45m range with an entry level deco course eg paid tech40, tdi andp, or ssi extended range? I think those courses qualify up to 10 mins of decompression on 50%? PADI tec40 is the most limited, but also has the best instructor that I’ve found, being the same guy that did my intro to tech class. Other than 5m less max depth, would there be any other limitations with PADI that I should know about?

I wasn’t planning on going tech so soon, but I’d love to make the most of some of the great diving we have on offer. Tia

What you want to do is still recreational diving, down to 50m with deco, according to European agencies such as BSAC or CMAS. My fully recreational certification is for 50m max, with deco on back gas (no accelerated deco).
And of course we started diving using twin tanks, which are usually more streamlined and balanced than a single large tank.
So, if you you just want to dive deeper and with some "light" deco, there is no need to enter the technical diving world, you can do this staying within the recreational system (with the proper agency, of course).
In my diving career I never felt the need to step over our European recreational limits, and go into the tech world.
Of course, if you want to PENETRATE in such a wreck, then you really need technical training (and equipment, and team procedures, and a specially equipped support boat, etc.).