my gosh--at 70 bar / 1/3 of a tank that must have been one heck of a swim.
So, this stuff isn't supposed to happen, but I guess it does
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kafkaland
Contributor
This is obviously a tangent, but I enjoy a bit of a surface swim at the end of a dive, too. It's a pleasant transition from the weightless and calm magic world underwater to the heavy feeling of gravity and the sometimes frazzled activity on the boat. Swimming back a little lets the underwater experience sink in some before the real world has me back.
mrdre
Contributor
1. NO! DO NOT get a bigger tank. It's a big mistake many make. At first it sounds intuitive: "well, you use more air - get a bigger air supply". NO! it's wrong. If you use more air, actually, you will need a SMALLER tank. Why? Because your buddies are planning based on THEIR consumption rates. In case you have a catastrophic tank failure, your buddy will share his air with you, planned for HIS consumption rate. You will breath your buddy's air out very fast leaving both of you out of air. You need a smaller tank, so once you are out of air, then your buddy's tanks will be enough for safe return to the surface.
2. The only solution for you - is to practice. There is no such thing as "I consume a lot of air and that's it". No. It's a skill too, and it's really not that hard. First, practice "yoga breathing" - use your diaphragm. Practice every day, take 10-15 minutes for that. Underwater do yoga breathing. Inhale slowly, exhale even slower. Experienced divers can exhale for about 40 seconds.
3. Practice finning, improve your trim. You will use much less energy and much less oxygen will be required.
4. In the scenario like this, I wouldn't swim against the current if I feel overexerted. I'd just do a surface swim. Once I had to swim on the surface for 3 hours against the current. Not that hard.
2. The only solution for you - is to practice. There is no such thing as "I consume a lot of air and that's it". No. It's a skill too, and it's really not that hard. First, practice "yoga breathing" - use your diaphragm. Practice every day, take 10-15 minutes for that. Underwater do yoga breathing. Inhale slowly, exhale even slower. Experienced divers can exhale for about 40 seconds.
3. Practice finning, improve your trim. You will use much less energy and much less oxygen will be required.
4. In the scenario like this, I wouldn't swim against the current if I feel overexerted. I'd just do a surface swim. Once I had to swim on the surface for 3 hours against the current. Not that hard.
DevonDiver
N/A
Let me be frank;firstly, I don't see many, if any, recreational divers "planning...their consumption rates". Secondly, this seems to be some sort of self-invented principle bastardized from some articles you read about gas-matching for overhead environment diving.
A little knowledge can be a bad thing - especially when it's used to formulate 'advice' that is presented as factual in public.
This is recreational diving. The whole point is to enjoy diving that is not avoidably foreshortened. Tank capacity is the obvious immediate solution to increasing dive duration. There is absolutely nothing wrong with opting for a bigger tank, or even multiple tanks (i.e. doubles or sidemount) to increase duration.
There are a number of intelligent solutions to ensuring a minimum reserve. Rock Bottom gas management is often cited on this forum - and worth investigating. That said, when holiday diving with insta-buddies, it is rare to encounter such a well prepared diving partner. BUT, from recreational diving depths, a general reserve (if respected and maintained) should be enough to provide sufficient gas for an emergency air-sharing ascent direct to the surface. Let's remember - safety stops are optional.
For some novice divers, always being 'the one' who exhausts their planned gas supply first is a very frustrating situation. It's one I can empathize with.
Reduction in gas consumption comes with experience. That's it. I, personally, don't believe that 'special breathing' techniques or practices makes a drop of difference. When I was a novice diver, I tried anything and everything to lower my SAC. I had high cardiovascular fitness, I had studied martial arts for years and knew proper breathing habits.... but nothing overcame the simple fact I had a large lung capacity. Nothing, that is, until I just gave up, accepted it was what it was... and stopped worrying about it... and THAT is when my SAC started to lower.... and lower....and lower.
Over the years and hundreds....then thousands....of dives, my consumption lowered to the point where I've got the best consumption of anyone in a group. My lung volume didn't change...nor did my breathing technique...I breath as normal....it was just relaxation and efficiency in motion.
Experience saw me relaxing more in the water...my buoyancy and trim improved.... I dived 'slower'....I didn't stress about my consumption.... I learned how to 'glide'.... I learned how to avoid over-exertion.
Dive...enjoy.... relax. If a bigger tank, or doubles/sidemount, helps you relax and remove air-supply woes from your list of stressors, then go for it....
I personally wouldn't recommend a pony for extending dive duration. As others have mentioned, there are better solutions for that. A pony is best used as an redundant gas supply - and reserved entirely for emergency purposes.
Situational awareness is often flawed when undertaking new activities, introducing new skills or operating new equipment. Unfamiliarity requires higher task focus, which detracts from the big picture awareness. It's not surprising to hear of a novice diver 'caught out' by gas consumption issues. Situational awareness will improve over time, as primary functions become more ingrained and require less mental 'processing power'. Until then, anticipate shortcomings by establishing routines for checking at regular intervals.... and erring on the side of caution with conservatism.
t4e
Contributor
unless your SPG is in a very unconventional spot it should be easy to monitor it, you just need to keep that in mind at all times and check it, especially when you know you're using air fast, overdoit at first if that's what it takes to get you into the habit, afterall your air is one of the most important parts of your safety underwater
i made a habbit if checking mine quite frequently at the begining of the dive just to make sure there are no issues, sure they can arise further into the dive but if at all possible why not deal with it at the beginning?
can also plan to do your safety stop while you still look around in the shallows, there's lots of pretty stuff there too
i made a habbit if checking mine quite frequently at the begining of the dive just to make sure there are no issues, sure they can arise further into the dive but if at all possible why not deal with it at the beginning?
can also plan to do your safety stop while you still look around in the shallows, there's lots of pretty stuff there too
terrylowe
Contributor
PhatD1ver, thanks for posting this. Sometimes when people are brave enough to post examples of their mistakes, some of the regular users here can be very sharp in their criticism and the OP gets offended and never returns. So far, the replies to your post have been quite gentle compare to what I've seen here. (That or the moderator has already been busy! ;-) One of the things that improved my SAC rate and diving enjoyment was getting in better shape.
mrdre
Contributor
Nope.. A diver 'A' (the air hog) uses 1/3 for the dive, 1/3 to get back and 1/3 for emergency. The diver 'B' (the buddy) has always 1/3 of the air of diver 'A', but because he/she breathes better than 'A', then that 2/3 is enough for both of them. Basically the idea is for the 'B' buddy to carry more air for 'A'. If 'A' gets bigger tank, then 'B' gets even bigger. It's just 'B' will end the dive with extra air. That's all.
---------- Post added July 12th, 2014 at 08:51 AM ----------
There are different schools of thought about that. Some say "it's recreational diving, let them do whatever they want", but others say "it's diving and nothing wrong with following the proper procedures since the very beginning". Let me give some points.
1. Planning the dives, calculating the air consumption rates, exercizing, seeing an improvement is actually fun. It ads fun to just "diving and looking at the fishes".
2. It makes the dives much safer. You say "it's just recreational diving". True, if people dive in warm easy waters where there are not much temptations to go deeper or swim into some caverns. But if the waters are difficult and if there are wrecks that lay deeper, caverns, etc. then the divers tend to quickly "break" those recreational limits. If you teach them only "dive and enjoy the dive, just have enough air to get out" then when they swim to the wreck laying somewhere on 130', that won't work. They will be asking for trouble. Why not start planning and executing the dives since the very beginning?
Also, I don't see anything wrong with buddies carrying extra air for the air hog. Neither there anything "special" in breathing slower. Some people can learn it fast (I learned on my 3rd dive after I noticed that my instructor would use 1 tank while we used 3 and I just asked him how he does it). Some people didn't even think about "breathing different", because in PADI class they've been told "breath deep and breath all the way". After I told my buddy about "breathing slow" he tried and improved his breathing in 5 dives. Before nobody ever told him and he thought "well, this is how you breath".. Why not let people know and try?
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+1 for what DevonDiver said.
Just to emphasize, so that new divers understand
What mrdre seems to be referring to is gas matching, but I think that he or she is misunderstanding how this actually works. In these scenarios, each diver needs to carry enough gas so that if there is a catastrophic gas loss at the furthest point in the dive, the remaining buddy has enough for them both to return to the exit point.
Planning is based on the concept of the controlling diver, which means that you plan so that - taking into account each divers tank size, starting pressure and SAC rate - the two likely scenarios (Diver A or Diver B losing gas) are both covered. SAC rate is one consideration, but its not in isolation. And if your buddy is planning based only on THEIR consumption rate, then they arent actually planning correctly.
As a practical matter, this calculation is typically done in overhead environments (cave, wreck or virtual overhead), where you need to calculate the amount of gas needed to get back to the ascent point. For the OP, its a bit simpler. Each diver needs to have enough gas so that at any time during the dive, if one diver loses all of his gas supply, the remaining buddy has enough gas for both of them to make a direct ascent to the surface. This is a much lower gas requirement. The OP should not be in any situation where such a direct ascent is not possible. Full stop.
Suggesting that a diver with a high SAC use a smaller tank because once you are out of air, then your buddy's tanks will be enough for safe return to the surface makes no sense to me at all. Your buddys tanks are only for catastrophic gas loss due to equipment failure. That is the ONLY excuse for running out of air. Those tanks, just like a pony bottle, should NEVER be included in your gas planning.
Finally, assuming that the OP respects NDLs, and assuming that we arent talking about carrying so much gas that extra tanks become a task loading issue (i.e. stage bottles, doubles for a new diver, etc..) there is never a downside of carrying more gas.
DevonDiver
N/A
Not really. The certifying agency are at liberty to completely define the outline of the certifications they issue.
Whilst I completely support a 'beginning with the end in mind' philosophy to dive instruction, it's important to recognize the issue of overload caused by inappropriately advanced instruction at an inappropriately early stage.
It's "beginning with the end in mind", not "begin at the end".
Your misinterpretation of 'gas matching' and the consequent inappropriate application to open water diving situations shows the danger of a trying to consume and apply too much information without the experience to balance it.
In this case, 'gas matching' is not a 'proper procedure'. Direct ascent to the surface negates it. Rock Bottom gas management is what is called for. That procedure makes gas matching irrelevant.
Recreational diving is primarily open-water diving. A direct ascent to the surface is always possible. Even in 'limited' recreational overhead dives (basic wreck, cavern or ice) certifications are issued with caveats; those being that the diver is never more than 40m/130ft (unrestricted access) to the surface. Again... this caveat ensures that gas matching isn't necessary.
One man's treat is another's poison. The fact is simply that the vast majority of recreational divers don't engage in gas consumption analysis or supplementary cardio etc, to improve their performance and planning.
Direct and immediate access to the surface. That is "just" recreational diving. Safe parameters that negate overly complex planning cycles from relatively inexperienced and less-than-comprehensively trained divers.
As mentioned, certifications are issued with caveats. The agencies define what their certifications permit. Training has to be matched with an outcome.
Should divers exceed the caveats of their training, then all points become moot.
You don't train recreational divers to the level of technical diving in the expectation they will need that training because they will exceed the limits of their certification. That's it really...
1. Gas matching has specific applications, as mentioned, none of which are relevant to open-water diving.
2. Beginning with the end in mind isn't the same as beginning at the end.
3. Complexity of instruction and diving has to match relative experience.
I do - as divers should be self-sufficient, even when operating inside a team.
But the point being made is that tank sizing is irrelevant to this discussion, and your previous advice to the OP was very ill-considered. The OP retains the option of direct and immediate access to the surface. At most, this is 4 minutes time-to-surface. An appropriate minimum reserve carried by each diver ensures sufficient gas for such an ascent to be made.
If divers wished to enact a more precision plan, then Rock Bottom would suffice. Gas matching remains irrelevant.
As mentioned; deliberate breathing strategies deviate from the norm. The norm = relaxed. Faster breathing is significant of elevated stress in the water. Stressing further about air consumption exacerbates, not remediates, that issue.
Artificial breathing patterns, especially in novice divers, can often cause knock-on effects; such as CO2 retention. These further antagonize efforts to reduce air consumption.
I've been teaching divers for over a decade... and have always been keen to further education wherever and however I can. The fact I disagree with some of the ill-informed stuff you've spoken as facts does not mean I am contrary to spreading knowledge. Rather... I just prefer to see the correct knowledge promulgated.... as appropriate to the diver, the dives they are doing and the dives they intend to do in the future.
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