4-Skills Every Advanced Open Water (AOW) Diver Must Have

[MidOH]

Mine are all wrenched down. Not very tight, but couldn't bump it loose or remove it by hand. It's just brass afterall.

 

[SlugLife]

I’ve heard of this happening to several divers here on ScubaBoard, but in over 60 years of diving, I’ve never experienced this. I do my own maintenance, and always tighten the LP hose to second stage down with a wrench. Is this not done now?

SeaRat

The way this happens, is there are some people who are telling divers to only hand-tighten hoses. So, when those hoses are only hand-tight, with no tool, they are susceptible to coming loose. The simple solution is to make them hand-tight, and then just slightly tighter using a tool, and that problem goes away.

 

[rongoodman]

I think this advice dates back to years ago from some groups doing extreme cave exploration, when it might have been necessary to take apart and clean second stages on the fly. It‘s hard to see how it has any relevance to recreational diving today.

 

[DeepSeaDan]

I had an incident where my regulator hose came loose at the 2nd stage, effectively blinding me with bubbles, and in all that chaos I couldn't find my octo.

Since then, I always have my regulators retained, so I always know where both are at all times, and I'm able to access them "blind" by feel alone. There are a variety of ways you can retain a regulator, but starting out with your octo on a necklace is fairly common. Personally, my "octo" (or pony, or other sidemount bottle) is on a chest-d-ring and breakaway clip. My primary is on a necklace. A lot of "advanced" divers will use a long-hose, wrapped in a specific way, which essentially retains itself.

Yikes! Can't say I've heard of that happening before; I did the long-hose wrap for many years, but now, I'm mostly a shallow water puppy.

 

[SlugLife]

Yikes! Can't say I've heard of that happening before; I did the long-hose wrap for many years, but now, I'm mostly a shallow water puppy.

These days, I always dive with redundant air on every dive. A similar incident now would just be annoying, but not scary or dangerous.

 

[Macan]

Be cautious not to over-tighten the LP hose onto the 2nd stage. The recommended standard tightness is 5 Newton-meters (Nm) for most regulators. To achieve this, initially tighten the hose using finger strength and then give it a slight nudge with a wrench until it reaches the point where it cannot be unscrewed further by hand.

It is advisable to use two wrenches for this process, one to secure the second stage while the other is used to turn the LP hose. Over-tightening the LP hose to the 2nd stage can lead to two significant issues. Firstly, there is a risk of cracking the 2nd stage body, which is typically constructed from plastic. Secondly, excessive tightening may result in damaging the Heat Exchanger O-Ring, leading to potential leaks.

 

[John C. Ratliff]

Be cautious not to over-tighten the LP hose onto the 2nd stage. The recommended standard tightness is 5 Newton-meters (Nm) for most regulators. To achieve this, initially tighten the hose using finger strength and then give it a slight nudge with a wrench until it reaches the point where it cannot be unscrewed further by hand.

It is advisable to use two wrenches for this process, one to secure the second stage while the other is used to turn the LP hose. Over-tightening the LP hose to the 2nd stage can lead to two significant issues. Firstly, there is a risk of cracking the 2nd stage body, which is typically constructed from plastic. Secondly, excessive tightening may result in damaging the Heat Exchanger O-Ring, leading to potential leaks.

Note that when I started diving single hose regulators, there were no plastic second stages. Yes, on plastic second stages, use two wrenches so as to not tighten against the plastic body. ‘Haven’t actually ever seen a “heat exchanger O-ring” on my second stages. Is that specific to a brand?

SeaRat

 

[Macan]

Note that when I started diving single hose regulators, there were no plastic second stages. Yes, on plastic second stages, use two wrenches so as to not tighten against the plastic body. ‘Haven’t actually ever seen a “heat exchanger O-ring” on my second stages. Is that specific to a brand?

SeaRat

See pic below. In cold water regs, there is a metal heat exchanger (see #8 in the pic) and the O-Ring (#9). Both heat exchanger and its o-ring is outside the body of the reg. When the LP hose is screwed in with only one wrench, it can cause the heat exchanger to further turn and tighten -- and may crush the o-ring. With 2 wrenches, one is to hold and prevent the heat exchanger from moving while the other wrench is to turn the LP hose swivel to connect to the 2nd stage. Hope this helps.

 

[tarponchik]

Clickbait.

 

[John C. Ratliff]

You need to kneel for learning how to use properly an ARO (chest mounted pure oxygen rebreather).
As in the forties and the fifties this was the standard scuba system here in Europe, the first generation of instructors did teach this way.
Unfortunately this is quite bad for back-mounted air tanks.
But after 15 years teaching the ARO on kneels, instructors here continued this way also when the ARO was superseded by OC systems.
However I always wondered how kneeling started in countries such as US, where the ARO was never widespread, and they started teaching directly with air tanks.
Laying flat on the bottom should have been easier (of course floating was almost impossible with no BCD and the tanks full of air)...

Well, let's go over some of the basics.

--Mask clearing; before most masks had a purge valve, you needed to be in a head-up position to clear the mask (although some were able to clear the mask with a side-down position of the mask). That is mostly achieved in a kneeling position.

--Clearing a mouthpiece of a regulator; the positioning of the mushroom exhaust valve is best when the regulator is tilted up if not using the purge button. Again, this is best achieved in the kneeling position. Clearing a double hose regulator's mouthpiece is also easier if vertical than horizontal if you are using the free flow with the mouthpiece above the regulator (many divers today don't even know what this means).

--Regulator exchange; we used to teach the divers to grab the shoulder strap of the receiving diver, then with your other hand take your second stage out of your mouth for the exchange, using buddy breathing techniques (before the octopus regulator was "invented").

--Doff and Don: on July 20th, 2021 I had to do an unexpected doff and don in open water, and actually recorded it with my GoPro camera. Here is that video:


Note that I was not completely horizontal during this process, and if I had tried it would have been much more difficult.

The horizontal position is now expected, and "trim" is important, because so many divers have abused coral reefs in the process of diving on them. So the kneeling position is not not something anyone recommends. But aside from the inside of a wreck, or in a cave, or over coral reefs, the kneeling position doesn't harm much. In the rivers I dive, kneeling causes no damage whatsoever.

SeaRat