One great clarification that came in for this video is when I mentioned "keep breathing" in concerns to preventing lung over expansion as you ascend, I should clarify that the goal of this is to breath in slowly if needed but mostly exhale, especially if your are rapidly ascending it might be better to keep the lungs mostly empty. Over expansion occurs as the air in the lungs expand so less air in the lungs is good in this case.
One clarification to suggest: when you say "keep breathing" during a controlled emergency swimming ascent, what you really mean is "keep exhaling". The air in your lungs will expand continuously as you ascend, and you need to keep exhaling (not inhaling) throughout the ascent to prevent an overexpansion injury.
Great call out and I totally agree with you, even if you keep breathing but take a giant breath in one can be in for a world of hurt. I do speak to this topic in some other videos I am scripting so will try to clarify this better in the future!
As usual, a reasonably good explanation, but the slightly more advanced tips are missing. The most important one is don't just check if you have enough, you could check if the reading makes sense. I was thought, in my very first diving course, to first estimate what the gauge should read, and only then check it. Assuming a single 12L tank and a reasonable gas consumption of 20L/min at the surface, that is almost 2 bar per minute, times the pressure at depth. So if you're at 15m, you should consume about 5 bar per minute. If you last checked 5 minutes ago, the gauge should read about 25 bar lower. This means you need to remember what it was the last time you checked. Usually, you will find that you have a little more than you calculated, but not too much. If you're still reading 200 bar 30 minutes into the dive, while you started at just over 200 bar, something is wrong. The gauge may be stuck, or your isolator valve is closed, if you dive doubles. It's all about awareness. Learn to sense when something doesn't add up, and don't dismiss it. Also, if you're diving to 40m, you really should be diving doubles, since the minimum gas you would need in a single tank for a 2 diver controlled ascent from 40 meters is 160 bar; by the time you get there, you have to leave. Minimum gas calculation: From 40 meters, at a controlled 3 m/min takes 14 minutes, with 2 divers each consuming 20L/min, at an average pressure of 3 bar, is 1680L of gas. Add one minute at 40m to manage the out of gas emergency, and calm down a little, that's another 200L. (1680L + 200L) / 12L ~= 160 bar.
Thank you for the great and thoughtful response and super valuable for others! I love the tip for calculating your consumption rate! I did mention this tip in the recent 25 tip video, but yes, that would have been a good one for this video, too! I do agree it's a great habit to be able to have a good idea and project how much will be used to train the intuition. The main goal is, as you said, to be able to understand consumption deeply, catch things when they aren't matching the projections, and also less likely to be caught off guard. I agree with you that 40 m is safer with doubles, and you have a great minimum gas calculation for the dive plan. I will say the ascent profile in your projection is a bit conservative as I know PADI mentions you can ascend at 18 m per minute which is super fast, but I know most divers use 10 m per minute up to safety stop. GUE teaches cut the maximum depth in half and ascend at 9 m per minute up to half, then hover for 30 seconds and then raise by 3 meter over 30 seconds, so 3 meter per minute up to the surface so that's 8 minutes to the top. Regardless, it's a great point, and I do agree with you that most risks under 30 meters to 40ish meters are significantly reduced with doubles. I'm still not doing doubles yet myself but I do plan to buy the gear setup early next year as I do agree it's generally safer, and I like the idea of improved balance. At least when we are diving near our home. We do a lot of travel diving, too, so single tank diving can't be avoided always.
I'm glad to hear you are okay! Out of air situations is one of the most dangerous things in scuba diving, but doing drills, practicing, and preparing for not if but when it happens helps turn something that could be devastating into something that your preparedness has mitigated. Something we should all aspire for and practice.
I actually witnessed my dive buddy drown in front of me back when I was 17 he was 19. We were deep and got separated from the group and he was a bit reckless.
Thank you for sharing, that's a truly hard situation for anyone to recover from. Scuba diving can be quite dangerous which is why I hope we can all aspire to be safer and help keep the sport fun and safe as possible.
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One great clarification that came in for this video is when I mentioned "keep breathing" in concerns to preventing lung over expansion as you ascend, I should clarify that the goal of this is to breath in slowly if needed but mostly exhale, especially if your are rapidly ascending it might be better to keep the lungs mostly empty. Over expansion occurs as the air in the lungs expand so less air in the lungs is good in this case.
One clarification to suggest: when you say "keep breathing" during a controlled emergency swimming ascent, what you really mean is "keep exhaling". The air in your lungs will expand continuously as you ascend, and you need to keep exhaling (not inhaling) throughout the ascent to prevent an overexpansion injury.
Great call out and I totally agree with you, even if you keep breathing but take a giant breath in one can be in for a world of hurt. I do speak to this topic in some other videos I am scripting so will try to clarify this better in the future!
Very good explanation.
Retired PADI DIVE MASTER
Super appreciate this message and glad you enjoyed it!
As usual, a reasonably good explanation, but the slightly more advanced tips are missing.
The most important one is don't just check if you have enough, you could check if the reading makes sense.
I was thought, in my very first diving course, to first estimate what the gauge should read, and only then check it. Assuming a single 12L tank and a reasonable gas consumption of 20L/min at the surface, that is almost 2 bar per minute, times the pressure at depth. So if you're at 15m, you should consume about 5 bar per minute. If you last checked 5 minutes ago, the gauge should read about 25 bar lower. This means you need to remember what it was the last time you checked. Usually, you will find that you have a little more than you calculated, but not too much. If you're still reading 200 bar 30 minutes into the dive, while you started at just over 200 bar, something is wrong. The gauge may be stuck, or your isolator valve is closed, if you dive doubles.
It's all about awareness. Learn to sense when something doesn't add up, and don't dismiss it.
Also, if you're diving to 40m, you really should be diving doubles, since the minimum gas you would need in a single tank for a 2 diver controlled ascent from 40 meters is 160 bar; by the time you get there, you have to leave.
Minimum gas calculation:
From 40 meters, at a controlled 3 m/min takes 14 minutes, with 2 divers each consuming 20L/min, at an average pressure of 3 bar, is 1680L of gas. Add one minute at 40m to manage the out of gas emergency, and calm down a little, that's another 200L.
(1680L + 200L) / 12L ~= 160 bar.
Thank you for the great and thoughtful response and super valuable for others! I love the tip for calculating your consumption rate! I did mention this tip in the recent 25 tip video, but yes, that would have been a good one for this video, too! I do agree it's a great habit to be able to have a good idea and project how much will be used to train the intuition. The main goal is, as you said, to be able to understand consumption deeply, catch things when they aren't matching the projections, and also less likely to be caught off guard.
I agree with you that 40 m is safer with doubles, and you have a great minimum gas calculation for the dive plan. I will say the ascent profile in your projection is a bit conservative as I know PADI mentions you can ascend at 18 m per minute which is super fast, but I know most divers use 10 m per minute up to safety stop. GUE teaches cut the maximum depth in half and ascend at 9 m per minute up to half, then hover for 30 seconds and then raise by 3 meter over 30 seconds, so 3 meter per minute up to the surface so that's 8 minutes to the top. Regardless, it's a great point, and I do agree with you that most risks under 30 meters to 40ish meters are significantly reduced with doubles.
I'm still not doing doubles yet myself but I do plan to buy the gear setup early next year as I do agree it's generally safer, and I like the idea of improved balance. At least when we are diving near our home. We do a lot of travel diving, too, so single tank diving can't be avoided always.
Happened to me. In those days no reserve tanks. Tried to exhale while
ascending. Very scary but if you panicked you die!
I'm glad to hear you are okay! Out of air situations is one of the most dangerous things in scuba diving, but doing drills, practicing, and preparing for not if but when it happens helps turn something that could be devastating into something that your preparedness has mitigated. Something we should all aspire for and practice.
Thank you indeed❤
Thank you too!
I actually witnessed my dive buddy drown in front of me back when I was 17 he was 19. We were deep and got separated from the group and he was a bit reckless.
Thank you for sharing, that's a truly hard situation for anyone to recover from. Scuba diving can be quite dangerous which is why I hope we can all aspire to be safer and help keep the sport fun and safe as possible.