Twin cylinders??

[Akimbo]

Any recommendations welcome.

In an ideal world, you would carry as much gas as you are comfortably pack, have dedicated bailout or online backup gas system, and the skills to use in when everything goes wobbly.

 

[KenGordon]

Hello,

I am in a similar situation with the OP. Relatively new diver, big (1.9m, 100kg), not particularly fit with SAC rate of about 18-20lt/min. It has improved quite a bit (I started with ~25lt/min) but still it is high.

Recently I did some rec dives with another much more experienced diver. He was big and not very fit and he had high gas consumption too.

He was diving with twins (I think 10 or 12lt) and BP&W plus a 12lt “stage” as he called it. For the two daily dives he used most of the gas in the twins plus some of his “stage” air.

Looking at him I liked the “stage” idea for me too (I’d personally leave the twins/BP&W setup for later).

Is it possible to dive with single 12lt AL tank on a usual jacket BCD and a 12lt “stage”??? Once I reach 50bars or so in my main tank I’d switch to the stage until the end of the dive. For the second dive I’d use a new 12lt main tank plus the remaining air from the first dive in the stage. Is that setup possible / recommended and if so what training is needed?

For me that would have several benefits. The main one is to have an extra independent gas supply. More than that I'd have more than enough air for my dives and "carrying" the stage didn’t look particularly uncomfortable at all. It also looks a good step towards more advanced setups and I’d guess practically it shouldn’t be that difficult to rent a stage in most places for a small extra cost.

Any recommendations welcome.
Thanks a lot

18-20l/minute may not be excessive, it depends on the conditions.

If using a stage in addition to a single you need to be aware that you have to keep a reserve for your buddy. So if you have an octopus setup on the back gas but only one second stage on the stage you must not breathe the backgas all the way down as you will have nothing left accessible to a buddy.

Personally, I would breath the stage first.

There are some techniques involved which are a lot easier when taught by an expert. Storing the used stage regulator is one, dropping and picking up a stage is another.

Again, using a large single will be easier if one is available. Getting more relaxed is also better than adding more gear.

 

[2airishuman]

Is it possible to dive with single 12lt AL tank on a usual jacket BCD and a 12lt “stage”??? Once I reach 50bars or so in my main tank I’d switch to the stage until the end of the dive. For the second dive I’d use a new 12lt main tank plus the remaining air from the first dive in the stage. Is that setup possible / recommended and if so what training is needed?

It depends on the jacket BCD. You need a shoulder and a waist D-ring. Some have them in the right places, some do not. Sometimes they can be added. It is also important to have a means of stowing your primary regulator. Most divers who use stage cylinders have bolt snaps on their primary regulator and snap it off to a D-ring on the right chest when not in use.

While strategies for using a stage differ, the general practice is to use the stage first, then the back gas, because a stage cylinder does not have connections for a power inflator or a secondary regulator for sharing air with another diver.

Any recommendations welcome.

A larger single cylinder may be more practical in place of your 12l AL.

 

[Kenmx10]

Let me be clear, descending without a regulator in your mouth is a stupid thing to do.

I think your missing the point. I never advocated that others start their dives without a regulator in their mouth. In fact , I stated that sometimes "I forget" because of habits pertaining to free diving . Then again I may be able to dive deeper without a tank on my back than you can with a regulator in your mouth. So my comfort level might just be different than yours. Either way you've criticized just about everything Ive said. And some of your comments are biased , not true and limited to your own experiences. Maybe Myself and others might feel comfortable breathing oxygen straight from the atmosphere when above water to conserve air, and maybe you feel you need to have the regulator in your mouth at all times to feel comfortable. Thats your right and opinion. Not mine or everyone else . Fortunately I know how to reach out, grab my regulator, and put it in my mouth, in and out of the water. "As my Buddy does his thing?" And I know how to fully open the valve before getting in the water, which was one of your concerns. Or swim 5 feet to the surface "if something goes pop" or an undetected failure occurs, which could happen EVEN if the regulator is in your mouth by the way. Thats why we are taught how to deal with these type of problems in basic open water certification.

"The rate of gas use at the surface is a fraction of that on the dive."- maybe in your case . Ive seen new divers struggle getting in the water, struggle at the surface, struggle fighting the currents, struggle fighting the seas, struggle getting to the morning line to start their descent. And by the time they reach bottom they are almost completely out of air. So your statement is not global , and does not apply to everyone.

Also breathing is not only about getting rid of CO2.

I think you failed to get the point of this thread. A person pretty much stated that they are blowing off air, twice as fast as everyone else. And is thinking about strapping another tank on their back just to try and keep up with everyone. If they are having difficulties with one tank, sound advice would not be , strap 2 HP 120's on your back and you will be fine. That will only create more issues to contend with if they can safely carry that much weight without hurting themselves and others. So while you might not appreciate any of the advice given "watch more experienced divers , learn from professionals, try to imitate their breathing patterns, practice, and look for ways to conserve air when out of the water", it wasn't directed toward you. The only thing that I mentioned that applied to you was in the very last sentence.

So, Let ME be clear, many of YOUR statements are uncool: "You may think it is the height of coolness, Have no clue, Stupid"
From my standpoint it sounds like I may know a few things that you haven't learned yet.
So Im not going to be responding to any more of your insults and hope you won't be reading any more of my post.

 

[KenGordon]

Nobody is telling the OP to take two large cylinders. He is being told that if he cannot improve enough to match his daughter by practice then a practical way, when on holiday where large cylinders are not available, is to sling whatever is available.

I am criticising you. In particular over the risks involved with descending. You seem to be 'blowing your own trumpet' by reference to being a free diver and that leading you to some bad practice as a diver. You do it again above saying you have probably free dived deeper than I have dived. You didn't need to say either of those things to get over your points to the OP. Nor did you need to reveal your lack of knowledge about nitrogen loading.

Did you watch the video I linked to? You would certainly find it educational if you don't understand the relationship between co2 production and the requirement to breath properly on scuba.

My intent in posting these things is not to hurt your feelings but to point out that you might want to look into the facts of some of these things and improve your understanding. That is why I derectly addressed my comments to you rather than the OP.

Your descent argument seems to be 'I have been trained and I will not make a mistake'. Well almost all the people that die having got in with their gas turned off were trained too. People make mistakes, but the systems adopted in scuba try to make the consequences not so bad. The system is that you put the regulator in your mouth and breath before you descend so you know it is safe to do so.

Your descent and surface behaviour comments are bad practice. They are probably worse in the cases you cite in the last post. If a diver is struggling at the surface the last thing they need is to inhale water.

 

[Steveed]

Regarding not breathing your gas at the surface. That is fine if diving a mill pond. In the sea with waves it is not such a good plan.

Agree with everything except having the reg in mouth at all times while on the surface. Do I misunderstand your statement, or am I wrong? Sincere learner here...

 

[KenGordon]

Agree with everything except having the reg in mouth at all times while on the surface. Do I misunderstand your statement, or am I wrong? Sincere learner here...

When learning you ought to keep it in your mouth to develop the habit. It you need to tell a buddy something or shout at the boat then sure take it out. If you subsequently dive in very flat surface conditions then decide if you are happy with it out in those conditions.

I teach people in a pool, then a lake and then they dive in the sea. In UK seas you are severely at risk of inhaling water at least half the time. Even in some places like Cozumel or the Red Sea a bit of wind will bring a significant chop.

Rather than finding out the sea I see more hostile than a pool the hard way I get students to keep their regulator in unless we need to talk. The lesson briefing ought to mean we do not need to talk unless I mess up.

Survival suits have splash hoods to reduce the chance of a person inhaling water.

You may see cave gurus debriefing in the water, those are not ocean conditions.

In a lake you might swim a distance on your back to reach a buoy, you might not bother with the regulator then, again the risk of an unexpected wave is small.

At then end of a dive you want gas available to use waiting for the boat and climbing back on board. If other divers are a distance away you might easily wait 15 minutes for a pickup. Personally I don't enjoy breathing salty spray for that long. It is also tiresome having to keep facing the waves. A snorkel is an alternative if the waves are not too big.

It is especially true when climbing a ladder back onto a boat. You don't want an extra dangly thing to catch and if you fall off then having a regulator in your mouth will be a big advantage.

You may dive in places with easy surface conditions, but like you train and dive prepared for the unlikely event of someone going out of gas, you ought to be prepared to surface in nastier weather.