Learned Wrong...

[boulderjohn]

But you got at LEAST one more drink out of it, right?

That might not be a bad way to mooch free drinks, you know...

I think that if I hung around bars waiting for people to ask me questions ab out scuba in the hope that they would buy me a drink later, I would be very thirsty.

[Dave1981]

"Modern tank valves can't be jammed open so you should open them all the way."

I can't be the only one that's seen them stuck on dozens of times on cattle boats? A bit of muscle will unjam them at the surface, however once during a course after a simulated failure my buddy turned my left post all the way on. On the flow check while resetting I couldn't move it to check the position, it's tricky to get any leverage with your hand behind your head. So whereas before my opinion was do what you like, now it's that all valves must be backed off a crack when opening. They do jam open.

Dave

[Akimbo]

If you put your mask on your forehead after diving a DM will come frantically to your rescue.

I have heard that… where the heck did that come from? I don’t do that much anymore anyway because of bi-focal lenses. I told a DM once not to even try it unless he saw the mask on my forehead, I disappear from sight, and he sees bubbles… even then; cancel it if the water turns red.

Somewhat related: Preventing mask loss vs a spare

[NWGratefulDiver]

I was taught by an instructor to turn my tank all the way on and then back a 1/4 turn. I know of two people (personally) now who have found it very hard to breath at depth by doing this.

... perhaps the instructor should've taught them which way was on and which way was off ...

... Bob (Grateful Diver)

[NWGratefulDiver]

I was taught that the frog kick is "not commonly used in scuba diving, but can provide a restful variation for long surface swims"
(Jeppeson's Open Water Sport Diver manual, page 18) ...

... Bob (Grateful Diver)

[DaleC]

The instructor did I'm sure but having a valve not completely open or closed means it can be a little open and/or a lot closed.

Someone accidentally closing an open valve and backing it off a 1/4 turn will be able to breath and inflate their BC on the surface during a pre dive check but find it very hard to breath at depth. unless they are also taught to look at the SPG to note a dip in the pressure (I wasn't) they will not catch this error themselves.
I have never personally seen a jammed valve but then I don't crank on them either. Even if it did jam I would prefer to resolve a non emergency on the surface than an air failure at 60'.
The experience for doubles may be different as you manipulate the valve at depth but I was taught this during OW and doubles were not mentioned. I also have a very large aversion to anyone touching my valve once the tank is on my back as I instinctively feel I need to recheck their check (if you know what I mean). In my early days I actually turned someone else's air off that way (left post, doubles).

[hypnodiver]

I was taught to BREATHE DEEPLY AND CONTINUOUSLY (shouting intentional.)

All I actually learned was how to have crap air consumption and crap buoyancy control.

[emoreira]

There are still old-school instructors out there that teach to deflate the BC before ascending.

This is still taught in my school, and after several dives I found this wrong or at least it produces to the diver an extra useless effort to ascend. The diver has to control the ascend speed and the air in the BC, but fully deflate the BC is useless.

[Insta-Gator]

Originally taught when OOA to ditch reg and blow bubbles while swimming up. Before OW class was over they changed it to keep reg in mouth to possibly catch one last breath before surfacing.

[oreocookie]

Ok, so it's not exactly learning wrong as portraying wrong, but I was recently reading a disaster novel that had occasional scuba references, all of which made me cringe. First he had divers talking about their oxygen tanks and oxygen gauges, ugh, mental headslap but I continued on. Later he had people (who were about to get caught in a tsunami) screwing octopus hoses onto tank valves and saying that they only needed 3 tanks between 6 people since divers always have a spare regulator dragging behind them in case their buddy ran out of air. A couple of paragraphs later, he referred to the second stages as respirators. I cringed and then continued to enjoy the rest of the story. I just looked at the author's bio on his website... he's a diver.

What I feel I learnt wrong, probably among other things, is an error of omission: The inflator hose is not the only way to dump air from a bc, but I guess a dump valve behind your hip is pretty useless when you're almost never anywhere near horizontal.