Side Mount Yes/no?

[matt_w]

For local diving, I suppose you could do twin 40s. But traveling, It would either be a single lopsided 80 or twin 80s.

Anyone ever tried belly mounting a single 80? That could be an interesting compromise...

Maybe someone has tried, but there is not really a good reason to . It is pretty easy to be comfortable with a single 80 on either side. You can offset the tank with a pound or two of weight if needed (you don't need 5 pounds to do this). However, with a good harness and a little practice you can swim and hover comfortably with good trim and just one aluminum tank.

 

[eelnoraa]

I completely don't understand why the ability to reach tank valve needs to be argued. It is a critical skill. True that it is more critical diving double especially with deco obligation or overhead environment. It is still critical in single tank rec dive. If you have a flow flow regulator, you go to your buddy, once air share is secured, you should turn off the tank. Sure your buddy can do it for you, that is why it is less critical for single tank. Ever try to do a proper ascent with reg free flowing?? The noise, the bubble, it is impossible to concentrate, or even read the gauge properly. You only think it is not needed because you haven't need to do it.

 

[uncfnp]

I completely don't understand why the ability to reach tank valve needs to be argued. It is a critical skill. True that it is more critical diving double especially with deco obligation or overhead environment. It is still critical in single tank rec dive. If you have a flow flow regulator, you go to your buddy, once air share is secured, you should turn off the tank. Sure your buddy can do it for you, that is why it is less critical for single tank. Ever try to do a proper ascent with reg free flowing?? The noise, the bubble, it is impossible to concentrate, or even read the gauge properly. You only think it is not needed because you haven't need to do it.

I appreciate your passion and it would be the ideal situation but as already pointed out it is not always a matter of training but physically impossible for some of us diving single tank back mount. There are alternatives. For me its usually a pony bottle and being hyperaware of my limitation, the risk and making double sure my tank is on before splash. And yes, I have done an assent with a freeflow primary.

 

[DevonDiver]

If you have a flow flow regulator, you go to your buddy, once air share is secured, you should turn off the tank.

For 99.9% of divers, that is not what they are taught. Free-flow regulator breathing is a skill on OW, and it includes an effective compensation for the issue of bubbles disrupting vision. We are talking about recreational divers, with clear and uninterrupted access to the surface. Air-sharing is a secondary option. Shutting off tank valves is not discussed. It is simply not a priority, given the time-to-surface.

If air-sharing were the elected course-of-action, then the bubble/mask problem is more easily solved by simply holding the freeflowing second stage away from the diver.

Teaching shut-downs to recreational single-tank divers is one of those 'bright ideas' that might actually turn very sour in practice. It delays the immediate ascent and it adds complications to an otherwise straightforward and obvious course-of-action. There is a potential for catastrophic mistakes to be made.

One basic principle of technical diving is K.I.S.S. This is relevant to the design of procedures and protocols for diving emergencies. The KISS principle applied to emergency procedures is well argued through Hicks Law:

RT = K log2 (N + 1)
where
RT = reaction time, K = a constant and N = the number of possible choices​

In a nutshell, Hick’s Law states that the more ways you have to respond to an emergency, the longer it takes to react. It also states that reaction time increases greatly for each additional option.

 

[eelnoraa]

I can see the reason of PADI's choice, but after experience it once, I don't think it is the optimal method. I can't argue with Padi's standard, just want to share my experience.

If air-sharing were the elected course-of-action, then the bubble/mask problem is more easily solved by simply holding the freeflowing second stage away from the diver.

This definitely doesn't solve the bubble in face issue. In my encounter, there were so much bubble. Once left the bottom, I couldn't even tell if I am ascending at all. My one hand was holding the reg, the other hand holding the gauge which I couldn't see, and trying to operation the BC at the same time. If it was not for my buddy, I didn't think I can keep track of my depth at all. Not to mention the freezing cold air coming out from the FF reg.

 

[DevonDiver]

This definitely doesn't solve the bubble in face issue. In my encounter, there were so much bubble.

I don't really understand your point. If you opt to air-share, you can hold the freeflowing 2nd stage out at arms length. There's no impediment to sight nor operation.

Shutting down a single cylinder is an added factor in an otherwise absolutely simple scenario.

OW divers are taught to tilt their head to protect the mask from being jostled/flooded, to breath from the free-flow and ascend. Brutally simple.

However, breathing from the free-flowing regulator may become problematic. I understand this, as I had a freezing cold free-flow many years ago...and breathing from the free-flowing 2nd stage soon started to coat my teeth with ice (ouch...!). I resorted to using my pony. If I hadn't got a pony, I would have signalled my buddy for an air-share.

If the diver needed to share air, then they can solve the bubble/mask issue by simply holding their regulator away from themselves... or even by tossing it over their shoulder behind them. There is no need, or cause, to shut down the cylinder in that circumstance. Indeed, stopping to attempt a shut-down would take nearly as long as the ascent itself for most recreational divers...

Shutting down a single cylinder is a solution to a non-existent problem. It also confuses KISS emergency protocols....and risks an incorrect, confused or panicked response that could leave the diver out-of-gas at depth. A freeflowing regulator is breathable. There's simply no need for it to be shut down on a recreational single tank dive....and if the diver messes up there could be catastrophe.

I see no logic in replacing a free-flow scenario (less dangerous) with an out-of-air scenario (more dangerous)..... and that, in essence, is what you suggest.

Sidemount or backmount doubles is different. Shutdowns exist to preserve gas that'd otherwise remain accessible and critical for safe conclusion of the dive. That's a very different requirement to what you are suggesting.

This is one rare issue where, I believe, technical protocols are not suited to recreational diving.

 

[soggybadger]

As a mental exercise, everything you just said is true. In the real world, it rarely happens that way. People who experience these failures aren't necessarily overweighted ... and while I agree it's a common error, it's not generally either the primary or proximate cause of a diving accident. And most divers generally won't think to dump weights because they've never actually done it before. Even in a balanced rig, once you attain the surface you need to be able to remain there, and that's really the proper place and time to consider dumping weights. But many people don't. After all, most divers never practice dumping weights in a class. And almost nobody practices the skill outside of class. And if you don't practice a skill, you don't have that skill ... what you have is knowledge that works well from the safety of your keyboard. But in a moment of stress it's unlikely you'll think to put that knowledge to use.

And what about the buddy ... where's he? Well, classes always tell you that you should dive with a buddy, but they often neglect to actually teach you how. It's common to see dive buddies descending at different rates ... to watch one buddy have an issue and attempt to arrest their descent while the other buddy keeps descending without noticing. Why is this? Because they never actually were taught how to descend together, maintaining eye contact on the descent. Or, more commonly on typical vacation dives, because you're descending as a group, and you may not even know who your "buddy" is. Unless you know that person, and have dived with them often enough to be familiar with their skills, you cannot count on a dive buddy to be handy if you should suddenly need air. That leaves an alternate air source that you carry on your person as your backup plan. And again, it's useless unless you've practiced deploying it under moments of stress ... because stress changes everything in terms of what you'll think to do in an emergency.

Easiest way to avoid this type of mistake turning into a tragedy is to learn how to manage your valve, and practicing it on every dive ... just after the descent, reach back and give it a quick turn, first one way then the other, verifying that it's fully open at the end of the exercise. This gives you knowledge that it can be managed, it gives you muscle memory that it can be done, and it gives you confidence that you can manage it in a moment of stress. Then you'll have something to fall back on if it should be needed that's more substantial than an internet or classroom conversation about something you've never actually tried to do before. Also work on buddy skills ... particularly on staying together and making good eye contact on descents, where problems of this nature are most likely to occur. Descend together ... watching each other. That way if one of you has a problem the other is there to help out.

Don't assume that just because you "know" how you'd handle a situation that you would react that way in a real emergency ... I've asked many divers after a minor mishap why they didn't think to do things they were taught to do, and they invariably admit they just didn't think to. Why? Well, usually because once the class was over they never thought to practice it again. Skills only work when they're ingrained ... and a skill that can't be practiced on a regular basis is questionable at best in an emergency. We don't dive on the internet ... and classes are an artificial environment. Skills need be practiced, both for the muscle memory and the self-confidence that you're prepared to deal with an emergency. Those who fall back on skills that they never tried, or don't practice regularly are taking risks they may not even be aware of.

There's a massive difference between knowing what to do and being capable of doing it during times of stress ...

... Bob (Grateful Diver)

Very true Bob.the misses nearly drowned on our ow class doing a cesa due to being heavily overweighted by our instructor. She made the surface but couldn't stay up and sank like a stone. Didn't think to pop her Reg back in and nearly didn't make it ( rescue boat the lot).our instructor was tangled in a line and couldn't get to her. She was too busy concentrating on getting it right to just get her Reg in whilst sinking and then sort out her buoyancy. Schoolboy mistake I know but we were green as.I reckon she was so focused on trying to scrabble to the surface that she didn't think of the obvious. Muscle memory, practice and experience would have sorted that one out no bother. It scared the **** out of one of the other students and he jacked the rest of the course in on the spot. The wife went straight back out and aced the cesa no bother. Just goes to show how easily you can screw up when things go pear shaped. Btw when we checked her weight she was nearly double what it was supposed to be and had been telling our instructor she had to much weight but was told she didn't have enough and they kept putting stones in her bcd.I can't remember why they thought she needed more.

 

[soggybadger]

Very true Bob.the misses nearly drowned on our ow class doing a cesa due to being heavily overweighted by our instructor. She made the surface but couldn't stay up and sank like a stone. Didn't think to pop her Reg back in and nearly didn't make it ( rescue boat the lot).our instructor was tangled in a line and couldn't get to her. She was too busy concentrating on getting it right to just get her Reg in whilst sinking and then sort out her buoyancy. Schoolboy mistake I know but we were green as.I reckon she was so focused on trying to scrabble to the surface that she didn't think of the obvious. Muscle memory, practice and experience would have sorted that one out no bother. It scared the **** out of one of the other students and he jacked the rest of the course in on the spot. The wife went straight back out and aced the cesa no bother. Just goes to show how easily you can screw up when things go pear shaped. Btw when we checked her weight she was nearly double what it was supposed to be and had been telling our instructor she had to much weight but was told she didn't have enough and they kept putting stones in her bcd.I can't remember why they thought she needed more.

Btw she didn't drop her lead because our instructor was bellow her and several other divers were bellow him.

 

[Neilwood]

...

There's a massive difference between knowing what to do and being capable of doing it during times of stress ...

... Bob (Grateful Diver)

A lot comes down to the mindset of the individual as well as their training.

I am quite lucky in that I have a number of years (around 20) of providing and being a trainer for first aid so I am quite comfortable with the principle of pausing a moment when the brown matter hits the air moving equipment to allow my brain a chance to take in what is going on and properly process it. It is so ingrained in me through practise and training not to just jump to a solution and potentially make things worse but to pause and think about it.

I realise that I am probably the exception to the rule though. Most divers will probably only dive a handful of times a year and if we are lucky remember their training well enough to cope.

For those suggesting that valve drills should be done by all I would suggest that, while being a necessity for technical diving where deco obligations and gas limitations are issues, they are most definitely an optional thing for OW divers who are sticking within their training. Even on a deep dive where things are a little more critical, a catastrophic failure resulting in an OOA situation or a free flow should be dealt with by air share and surface at the earliest possibly time, CESA or buoyant ascent. OW divers should never be in situations where these options are not suitable - if they are they are exceeding their training.

If a diver splashes without their valve open and somehow doesn't realise it until they have dropped, then there are two options: 1) air share while they or their buddy opens it or 2) surface, sort it and continue the dive.

 

[Diving Dubai]

We as divers are somewhat like other sports persons and other professionals. We convince ourselves that accidents only happen to others and we are infallible because we train and practice etc etc.

Clearly this isn't true.

I would draw people's attention to an incident in 2013 where a Scubaboard Staff member perished. Someone who was an instructor and used to demonstration things like ditching weight, 15 years of experience, over 5000 career dives etc

The thread is here The long and short was that the person went OOA (was over weighted) and failed to drop their weights.

The person drowned in 12' of water.

As @NWGratefulDiver pointed out, people react differently in an emergency. Only once you've been in a specific situation do you understand how you'll react