Half an hour, for my wife at Biscayne National Park. The basics taught on the boat to the reef, then they throw you over the side. She describes it possibly the single most awesome and spectacular event in her life.
If one is starting from a place of never-having-done-this-before, is the learning curve for a modern rebreather system too much to start with?
There are a few different types of rebreathers, some much more complicated than others. Even a fairly basic semi-closed system like the Dräger Dolphin requires some significant skill. Basic things like recovering a dislodged mouthpiece must be done in a very particular way to avoid getting a mouthful of caustic chemicals. Fully closed systems would at least require strong cautions about dive planning since you could get into a lot of trouble diving too deep and too long since running out of air wouldn’t be a limiting factor.
On the plus side, a brand new diver may not have as much difficulty with fine tuning buoyancy control as some experienced divers have when switching to a fully closed rebreather. Experienced divers make fine buoyancy adjustments using lung control, but it doesn’t work the same when your exhaled breath is captured in a bag attached to your gear.
I’m taking these, too, as promising “end points” in the spectrum. You’re making me feel comfortable that this can happen.
Now, if I were doing it in real life, I’d probably go with something more studied and gradual – but I’m a terrible coward. For a character in a book, I feel okay, now, depicting a briefer – dare I say it – immersion period.
Thank you all again!
The important note for these quick session is they teach you how to survive when everything goes well. There are many things that can go poorly, and if one of those happens and you don’t have an expert with you, you might be seriously injured or die.
I taught my sister to breath through a regulator attached to a tank in a pool, and, importantly, how to safely get out of the pool afterwards. (If you inhale from the tank under water and hold your breath while surfacing, you can actually injure yourself.)
It was an check to see how she would like it, before going on to a real scuba class. I would never do that with someone in something more complicated than a pool.
I’ve done this too. My uncle had been diving for a few decades and took me out once to explore some reefs. He spent a few minutes talking about and demonstrating the gear, and then we got in the water. (The hardest part was that first breath underwater). However he was next to me the entire time, and it was maybe 8’ deep. A certification takes more.
OP, are you sure that you want to take the quickest route? When you’re diving, you are in an environment which in itself isn’t conductive to human life, and properly assessing the risk of that isn’t trivial. There’s a saying among some divers that “you don’t know what you don’t know”. Slow and considered will reduce the amount that you don’t know what you don’t know, thus giving you a better chance to make an informed decision about the level of risk you’re willing to take.
If you don’t know what you’re allowing yourself to be lead into, you might risk ending up like these tourists did. YMMV, but I get the screaming heebie-jeebies by the thought of dying that way.
I only dive OC (open circuit), but according to a handful of RB divers I’ve chatted with, a rebreather should at all times be regarded as a machine which will, if at all given the chance, do its best to kill you. On a more serious note, the design itself opens up a decent bunch of ways to die which an OC system will be very hard-pressed to come up with, like hypoxia or hypercapnia. While hypoxia probably is a fairly comfortable way to die, hypercapnia most definitely isn’t.
The cost, risk and complications of rebreathers are generally only worth it for those doing extended technical dives (helium is damned expensive, and dragging a dozen of stages and deco bottles needed for multiple-hour dives becomes too complicated at one point), and extremely serious and dedicated UW photogs who don’t want to spook their subjects with their bubbles.
I don’t there’s any doubt that you can take nearly any complete novice and have them doing a simple shallow dive in a matter of an hour or so as long as nothing goes wrong. If this is for a character in a book you’re writing then you can do so without veering off into the realm of unbelievability.
Since information is good, things covered in the full series of classes include (but are not limited to):
Your equipment, what it does, how to inspect it to make sure it’s in good condition, how to put it together, how to handle it in the water. How to get in and out of the water: how to walk in and out, how to jump in from a distance, how to roll off the edge of a boat. What to do when you come to surface and are waiting for the boat to pick you up. How to safely ascend and descend. How to read your dive computer. The chemistry/physics of gases in your blood and why it’s important to watch your computer. How to share equipment if your dive buddy’s rig goes bad. How to treat sea life. How to move efficiently so you save oxygen. What happens if you get narced or get the bends.
Me, personally, no way ever. (Alas, I don’t think scuba diving is something I will ever participate in, at all, ever in my life. Bummer, but that’s reality.) But this is for a book I want to write, and the protagonist has advantages I lack. (And maybe a couple of deficiencies, too!)
That’s much of what I was hoping to learn from this thread. I thank you all and everyone for the really good info. I wandered in with a ton of ignorance, and now I only am bearing 1900 pounds of ignorance!
Ah, OK, I didn’t notice that. Sorry.
Now if the protagonist takes a crash course like that and immediately starts diving, expect some, uh, “interesting” incidents. Like being hopelessly overweighted, descending like an anchor and crashing into the bottom. If the bottom is soft, he’ll immediately be surrounded by a thick silt cloud, unable to read his instruments or locate anything by sight. Or becoming overwhelmed by the struggle to kick efficiently in a current, taking a CO2 hit (moderate hypercapnia), panicking and rushing to the surface risking a gas embolism. I’ve seen the first with my own eyes, the other is not an extremely uncommon incident either.
If the protagonist is a James Bond-type superman, none of this will of course happen