Yes for caves. Caves are easy and safe compared to deep open ocean wrecks. Caves may actually be within the "reasonable to do recreationally" level, and WKPP is or was actually doing worthwhile environmental science too.
Outside of the US, helium is seriously expensive. I was figuring dual rebreathers, or rebreather + OC bailout. $800 in gas alone for a 100m training dive for TDI Adv Nitrox, open circuit.
WKPP and GUE definitely use teams to reduce the risk AND cost (although I have some issues with some of GUE), but at the same time, it reduces your flexibility. I really would want to only do tech diving with a group of people I routinely train with and trust, but I'd be ok with customizing our gear as a group.
Not using computers is just fucking unforgivably wrong, though. Using a computed table as your primary dive plan, sure, but you want a computer in case anything doesn't go according to plan, plus a bottom timer.
I wouldn't dive below 30m in a difficult environment without dual buoyancy on independent gas sources (drysuit + argon bottle, or twin tanks manifolded with BC on one and drysuit on the other, etc.). Helmets, especially with lights, can save your life. Snorkels can be useful if you do shore dives or long surface swims (although I throw it into a BC pocket). There are times when a big knife, prybar, hammer, etc. can be useful, and I never dive without shears and a knife. Solo dives are probably better for some wrecks (although maybe it being a solo-only environment makes it not worth diving there). Air at 30-40m is probably ok, although trimix at 40m+.
OT, but: That would be because it's rare and hard to extract and running out. It's only cheap in the US because in 1996 some genius passed a law requiring it to be sold cheaply to use up the US's helium reserves.
The likely result is that the world will be basically completely out of helium by about 2050. Too bad for anyone not-very-rich who needs an MRI scan at that point.
I'm betting we'll switch to hypoxic hydrogen ("Hydrox") for deep (>40m) diving then, or use atmospheric dive suits and ROVs only.
Hydrogen is a pain to deal with on the surface and in transport, but if you're putting it into something like 95/5 hydrogen/oxygen bottom gas, is not going to explode. At >30m, that's quite breathable. Some kind of hydrogen-based trimix is probably acceptable at that point. Continue to use nitrox and 100% oxygen for the shallow stops.
Hydrox might see some limited use for deep commercial diving (there have already been limited experiments) but it will never be rated safe for sport diving. The explosion risk at tank fill stations is ridiculous.
Definitely. There is already enough risk running high pressure oxygen given how some o-ring lubricants can react, I cannot imagine adding an additional fuel to the mix.
I am concerned because someone seems to have fed you a bunch of misinformation, and unfortunately we tend to believe most whatever we hear first. Technical diving is not some kind of high-risk, white-knuckle adventure. It can be safe and fun in most any reasonable environment.
Having a unified team actually increases your flexibility. When all your dive buddies have similar equipment and training then they're essentially interchangeable (within reasonable limits). Solo sport diving is always and everywhere a bad idea. You need someone to assist if you get entangled or have a serious equipment problem. Plus it's nice just to have some company and another set of eyes to spot interesting marine life. If you can't find a qualified buddy then just skip the dive; there is nothing underwater worth risking your life. There have been too many incidents of solo divers ending up dead for unexplained reasons, because there were no witnesses and no one to help.
The dive computers available today are simply not useful. The fundamental problem is that a computer can't accurately measure bubbles and dissolved gasses in your body. All they can do is run some simple, idealized models (i.e. "first assume a spherical cow") which are fairly close to what a typical person will experience during a limited range of dive profiles. For example, the models I have seen — including VPM, RGBM, and others — fail to properly account for the oxygen window during decompression and so will stretch ascent times out unnecessarily. A lot of divers lack the scientific background necessary to understand the difference between accuracy and precision. A dive computer will display highly precise numbers, but who knows whether they are accurate? Despite their limitations, the mathematical models are useful for understanding the general shape of the decompression curve across a spectrum of possible profiles. Once you understand that then you don't need a dive computer, or computed tables. No one I dive with would actually try to reference a table in the middle of a dive. If you want to waste money on an expensive dive computer then go ahead, just don't fool yourself into believing what it tells you.
Helmets are unnecessary for sport diving; don't dive in places where heavy things can fall on your head. A light on your helmet will blind your dive buddy when you look at him, plus having things stick out from your head is an entanglement hazard. Bring snorkel in your pocket if you want; it won't hurt but I've never found them useful. There's nothing wrong with bringing a bag of tools when you need them but please leave the wrecks intact so the rest of us can enjoy them, too.
I agree with you that tech diving can be safe and fun, but it is also possible for things to go wrong with deadly consequences. All I can say is that when I was doing technical diving you were always told that self-rescue was the first option. If your buddy and/or team can help you out then that was great, but we never dove with the assumption that our buddy or team would be able or available to help out. This means complete redundancy and ability to isolate failed components of your life-support system. It is not about solo diving, it is about sometimes being in a place where the only person you can truly count on is yourself.
The dive computers available today are simply not useful.
This is something I strongly disagree with. Dive computers are very, very useful. They can't measure bubble or various saturation levels of different tissue types, but neither can you. The models they use may be idealized and only have a fixed number of compartments for the offgassing calculations, but they provide several other benefits that make them a key component of any deep dive. For starters they track your depth over time. Everyone drifts and bounced around within a range of depths even when you think you are staying on a fixed depth over some portion of the dive. The computer is sampling and adding the depth changes into the model. This enables the computer to be more accurate than you can ever be. If you disagree with its model then you can do some research into what it is using as its basline profile and either buy a computer that uses a model you like or adjust its calculations according to how you think you fit its model (several of the dive computers you should be looking at allow for this latter option.)
I am not talking about diving on some recreational computer, I am talking about using a dive computer designed for mixed gases and dive profiles with a ceiling. If you are doing mixed gas diving you need a computer that can be set with the mixes you will use and be switched as you switch. Maybe you are good enough or experienced enough to get away without a computer, but I have always dived with a hand-caluclated profile (with various bailout options and numbers) in a BC pocket, a mental model of where I think I am in the dive running in my head, and a dive computer that can provide both accurate and precise info based upon its own model of the dive and diver.
You are still misunderstanding the difference between accuracy versus precision, and overestimating the level of accuracy that any dive computer is capable of providing. Depth fluctuations are just one factor in determining gas loading. Sure a computer can sample depth every second and integrate that over time, but so what? There are so many other variables and unknowns that the margin of error is huge; you're missing the forest for the trees. The profile that a dive computer will generate for you is still fundamentally suboptimal (i.e. inaccurate) in multiple ways. I am not a particularly skilled or experienced diver, yet I learned how to do this stuff with just a little practice; anyone who cares to try can do the same. I'm not "getting away" with anything.
Look, I understand that technically-minded people want to believe that there is a "right" answer and that problems can be automated away. But the reality is that no one fully understands how decompression works and the mathematical models are fundamentally not accurate enough to be useful in the midst of a dive. Better to accept a certain level of uncertainty rather than believe a falsehood. Free your mind.
Outside of the US, helium is seriously expensive. I was figuring dual rebreathers, or rebreather + OC bailout. $800 in gas alone for a 100m training dive for TDI Adv Nitrox, open circuit.
It has been almost a decade since my Adv Nitrox course, but I am trying to figure this one out. You are not doing trimix and from what I remember of the the course spec you are mostly working around bottom mixes that are hypoxic at the surface and dealing with a ceiling on the dive profile. Even with the bottom mix in dual cylinders on my back, a descent/ascent mix on once side an a 50% mix for the last few stops on the other side I can't see how you were getting charged $800 for the mix unless you were getting completely hosed on everything that was not a standard 32 or 36 recreational nitrox mix.
OTOH you are completely correct about it being a deceptively expensive hobby, even if you take the "cheaper" route and go with semi-closed rebreathers or even OC.
Nitrox, even 100% o2, is cheap. A lot of places do free nitrox now, it is just a little more hassle to analyze your tanks. Especially on boats with membrane systems.
Outside of the US, helium is seriously expensive. I was figuring dual rebreathers, or rebreather + OC bailout. $800 in gas alone for a 100m training dive for TDI Adv Nitrox, open circuit.
WKPP and GUE definitely use teams to reduce the risk AND cost (although I have some issues with some of GUE), but at the same time, it reduces your flexibility. I really would want to only do tech diving with a group of people I routinely train with and trust, but I'd be ok with customizing our gear as a group.
Not using computers is just fucking unforgivably wrong, though. Using a computed table as your primary dive plan, sure, but you want a computer in case anything doesn't go according to plan, plus a bottom timer.
I wouldn't dive below 30m in a difficult environment without dual buoyancy on independent gas sources (drysuit + argon bottle, or twin tanks manifolded with BC on one and drysuit on the other, etc.). Helmets, especially with lights, can save your life. Snorkels can be useful if you do shore dives or long surface swims (although I throw it into a BC pocket). There are times when a big knife, prybar, hammer, etc. can be useful, and I never dive without shears and a knife. Solo dives are probably better for some wrecks (although maybe it being a solo-only environment makes it not worth diving there). Air at 30-40m is probably ok, although trimix at 40m+.