Teaching ascent to new divers

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Respectfully, you can't really achieve any semblance of buoyancy control without getting trim down first and you prove my contention that most don't understand the correlation. I call being horizontal the "Scuba position" and other than mask clearing in shallows, it's the first skill I introduce. Not getting it first dooms the new diver to a hundred or more dives trying to figure out their buoyancy. Get it done first, and then teach the entire course with flat trim and neutral and your students look like rock stars when you're done. It's all about comfort, and a trim and neutral student is far, far more comfortable because they are in control all the time. If they're in control from the beginning, then you spend no time trying to keep them from floating away and they learn, far, far faster. In other words, there's a bit of a time penalty early on, but you make it up as the class continues.

Students that are in control do everything more easily and with less drama... and that includes ascending.

The class I did my open water and advanced was horrible (different places). I didn't know how bad at the time. It took me a long time to get my weights where they should be rather than over. Over 100 dives and much more classes later and I'm still learning new things, things that I feel should have taught or at least introduced during my open water class or at least I would have gotten them a lot sooner had I started training right from the beginning.

I was doing play time pool work on sunday and I overheard a instructor tell his open water class that to get certified they had to master flutter kick, frog kick, trim and show the beginnings of bouyancy control. ( I also know they do not over weight there students) I told the owner it is good to see a TIR (teaching it right)
 
Most divers I see on a boat are overweighted.

This story is funny or sad, depending on how one looks at it.

On a lobster dive down on one of the SoCal liveaboard, I was doing a swimming safety stop at the end of my dive and saw something on the bottom. I had plenty of gas for a look so I went down, saw it was a weight pocket, finished my trip to the bottom, picked it up, returned and resumed the 15' swim back to the boat.

Once on the boat I tried to find the owner, since it didn't look like it had been there long. I figured I'd asked everyone, and had it announced at dinner, so I thought I had some lead for my collection and a pocket to pass on.

The next morning one of the divers asked me if I had found his weight pocket. It seems when he lost it he managed to adjust for the problem but couldn't figure why he kept twisting to one side, but when he went vertical to surface the issue went away, and he surfaced normally. When he checked the next morning for dive, he saw the pocket missing.

I gave it back, after I first told him the claim time limit was up last night, and suggested he put that pocket weight in his dive bag, split the other pocket weight between the two, and get back to me after the dive and let me know what he thought. One of the boat DMs was behind him evesddopping, desperately trying not to laugh out loud.

Oh yeah, he liked it 'cause he didn't have to work so hard at the safety stop. Later during the trip we did a dive togather, he asked "...because you might know something else I don't". I took it as a complement.



Bob
 
I believe the RECREATIONal rules also include:
- do not kick the bottom, destroying it,
- do not kick up the bottom, destroying the vis for others.

Kicking (up) the bottom is rather hard when horizontal(ish) and very easy when slanted or vertical.

I'm not sure if you meant 'the notion of staying horizontal' in general or just also for the ascent.

Being horizontal also makes it easier to breath and reduces one medical risk, independent of it helping good depth control.

Pretty sure we are talking about ascent for new divers. Not trim. And definitely not trying to be the smartest person in the room.
 
Assuming you've been diving along at depth horizontal (to not kick up the bottom and for easier depth control), you've been controlling your depth by slight shifts in your breathing pattern. Whether to maintain depth, or go up or down a little depending on terrain. So horizontal ascent:
- is just a continuation of how you've been controlling and adjusting depth the whole dive.
- increases vertical drag, just like it did at depth, making depth control easier.
- makes breathing easier, just like it did at depth.

Sure, in the last few feet shift to vertical so you can do a 360 as you approach the surface. But below that, horizontal makes depth and breathing easier. A slight roll and twist lets you check above you periodically.
Thanks, makes sense. Only thing I'm not sure of is it making breathing easier, as I never noticed it being harder ascending (or at depth) vertically. But maybe there is a subtle difference?
 
Thanks, makes sense. Only thing I'm not sure of is it making breathing easier, as I never noticed it being harder ascending (or at depth) vertically. But maybe there is a subtle difference?
Yeah, I had to think about that statement on ease of breathing, and if generally accepted as true I would appreciate a cited source. I am thinking the only variation of position that affects the WOB is the relative position of the mouthpiece opening to the 2nd stage valve, the cracking effort measured in inches of water.
 
Thanks, makes sense. Only thing I'm not sure of is it making breathing easier, as I never noticed it being harder ascending (or at depth) vertically. But maybe there is a subtle difference?
The pressure pressing in on your lungs, relative to your mouth/reg, is greater when you are vertical. While when you're horizontal it is close to being equal. That makes drawing in the breath harder. By at least a couple inches, while we often bitch about .2 - .3 inches of increase in cracking effort for a reg. The easy way to see that is to float in a pool on snorkel, or just a mask. Breathing floating flat is easier than hanging vertical. Of course exhaling is easier if you are vertical, but is not normally much effort anyway.

The other part is that for the immersion pulmonary edema. Which is basically fluid in the lungs. An exacerbating factor was thought to be breathing resistance, needing to suck hard to get air in. The edema is where you get fluid from the body into the alvioli of the lungs, preventing breathing. Sucking in your air, the pressure difference between the air and your lung walls, acts as an extra factor pulling that fluid into the lung air spaces. Not saying that is a huge risk, but is it something to be aware of that the incident reports are paying increased attention to. I have not been tracking the latest on it this year, so there may be more up to date info.

Just extra reasons why you might as well be horizontal.

Annual Diving Incident Report
2016 video starting at 22:36 discusses it.

Yeah, I had to think about that statement on ease of breathing, and if generally accepted as true I would appreciate a cited source. I am thinking the only variation of position that affects the WOB is the relative position of the mouthpiece opening to the 2nd stage valve, the cracking effort measured in inches of water.
I don't have a citation, other than my experience and the physics adding several inches to that WOB on inhale and needing to resist that if you want a slower exhale. And the seemingly related concern rebreather pilots have with back mounted counter lungs.
 
The pressure pressing in on your lungs, relative to your mouth/reg, is greater when you are vertical. While when you're horizontal it is close to being equal. That makes drawing in the breath harder. By many inches, while we often bitch about .2 - .3 inches of increase in cracking effort for a reg. The easy way to see that is to float in a pool on snorkel, or just a mask. Breathing floating flat is easier than hanging vertical. Of course exhaling is easier if you are vertical, but is not normally much effort anyway.

The other part is that for the immersion pulmonary edema. Which is basically fluid in the lungs. An exacerbating factor was thought to be breathing resistance, needing to suck hard to get air in. The edema is where you get fluid from the body into the alvioli of the lungs, preventing breathing. Sucking in your air, the pressure difference between the air and your lung walls, acts as an extra factor pulling that fluid into the lung air spaces. Not saying that is a huge risk, but is it something to be aware of that the incident reports are paying increased attention to. I have not been tracking the latest on it, so there may be more up to date info.

Just extra reasons why you might as well be horizontal.

Annual Diving Incident Report
2016 video starting at 22:36 discusses it.
Good explanation and I follow the simple physics. The fluid in the lungs/breathing resistance aspect may be a concern, and something to check out when studies are completed (how many years...?) on the incident reports. For now, not something I'll worry about.
 
The pressure pressing in on your lungs, relative to your mouth/reg, is greater when you are vertical. While when you're horizontal it is close to being equal. That makes drawing in the breath harder. By at least a couple inches, while we often bitch about .2 - .3 inches of increase in cracking effort for a reg. The easy way to see that is to float in a pool on snorkel, or just a mask. Breathing floating flat is easier than hanging vertical. Of course exhaling is easier if you are vertical, but is not normally much effort anyway.

The other part is that for the immersion pulmonary edema. Which is basically fluid in the lungs. An exacerbating factor was thought to be breathing resistance, needing to suck hard to get air in. The edema is where you get fluid from the body into the alvioli of the lungs, preventing breathing. Sucking in your air, the pressure difference between the air and your lung walls, acts as an extra factor pulling that fluid into the lung air spaces. Not saying that is a huge risk, but is it something to be aware of that the incident reports are paying increased attention to. I have not been tracking the latest on it this year, so there may be more up to date info.

Just extra reasons why you might as well be horizontal.

Annual Diving Incident Report
2016 video starting at 22:36 discusses it.


I don't have a citation, other than my experience and the physics adding several inches to that WOB on inhale and needing to resist that if you want a slower exhale. And the seemingly related concern rebreather pilots have with back mounted counter lungs.
I will check the video later, but there is a major difference between sucking air through a tube and opening a valve that allows compressed air to flow on it's own and equalize an air space to ambient pressure.
 
I will check the video later, but there is a difference between sucking air through a tube and opening a valve that allows compressed air to flow on it's own and equalize an air space to ambient pressure.
Right but the second stage is equalizing the air space to the pressure the second stage is at. Your lungs are being pressed in by the water surrounding them several inches below that. So to draw your lungs open you have to push out against that greater pressure surrounding them.

Happy for a doc or rebreather pilot to step in. My experience in a pool with no gear, just mask pool suit and fins, bears out breathing flat on the surface is easier than hanging vertical. I think the physics is straight forward. I can not say I notice a lot diving, but I have not played with it deliberately there. Unless I go inverted in which case I do notice the reg pushing air in, once I crack the valve, for the reverse relationship of pressures.
 
Right but the second stage is equalizing the air space to the pressure the second stage is at. Your lungs are being pressed in by the water surrounding them several inches below that. So to draw your lungs open you have to push out against that greater pressure surrounding them.

Happy for a doc or rebreather pilot to step in. My experience in a pool with no gear, just mask pool suit and fins, bears out breathing flat on the surface is easier than hanging vertical. I think the physics is straight forward. I can not say I notice a lot in the water, but I have not played with it deliberately there. Unless I go inverted in which case I do notice the reg pushing air in, once I crack the valve, for the reverse relationship of pressures.
Work of breathing is measured across the full cycle, not just inhalation. If you are right that inhalation is harder when vertical, then exhalation should be easier for the same reasons, and come close to cancelling each other out. ...I think...
Hoping an SME dive MD weighs in...
 
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