Body orientation during a dive - what to avoid?

[garydemos]

During my OW training I rotated to a face-up (horizontal) position once while we were doing some buoyancy practice and the instructor motioned for me to rotate back to a normal face-down position. I never asked him about that later and have often wondered if there are any body orientations that should be avoided while diving. I did notice that while diving with some rented equipment in the ocean recently my regulator felt very different while breathing when I briefly went inverted and vertical - this did not happen with the equipment I was using for my OW cert. (I am getting all my own stuff before my next dive). Are there certain positions to avoid? I so - why?

 

[Colliam7]

During my OW training I rotated to a face-up (horizontal) position once while we were doing some buoyancy practice and the instructor motioned for me to rotate back to a normal face-down position. I never asked him about that later and have often wondered if there are any body orientations that should be avoided while diving. I did notice that while diving with some rented equipment in the ocean recently my regulator felt very different while breathing when I briefly went inverted and vertical - this did not happen with the equipment I was using for my OW cert. . . . Are there certain positions to avoid? I so - why?

Most regulator second stages will breath 'harder' and 'wetter' if you are inverted, as you describe your experience (the air wants to go 'up', but you are trying to pull it 'down' into you mouth). Having said that, there may be times when you want to be inverted (a big, beautiful sand tiger shark swims toward you from the front, and over you and you rotate to watch it), and breathing harder and wetter is not the end of the world. For the most part, underwater you want to be horizontal / face down (what you refer to as 'normal'). I actually have OW students practice swimming inverted, so they understand the difference in second stage performance in that position.

 

[Jorgy]

One that comes to mind right away applies to drysuit diving - vertical with feet over your head, the air in your drysuit goes to highest point which can make get back to a good horizontal position a problem - in a wet suit I can't really think of a problem position.

As a "developing" photographer I often find myself in strange orientations.

Your point about the regulator is valid - but I think that is more related to the reg itself - I think all the good high end regs work in all orientations and stay easy and dry.

M

 

[Doc Harry]

Naw, the only positions to avoid are those that damage the reef or stir up the bottom.

It is often useful to practice being in a variety of different positions. The supine position that you describe is great for blowing bubble rings, and for staring up at the surface during your 3-minute safety stop. Sometimes the vertical head-down position is the only way to look at something without damaging the reef.

Scuba is a 3-D sport, take advantage of it!

 

[spectrum]

Garydemos,

There are no physiological issues with body orientation while diving. I do find that if I do barrel rolls and other antics I will have water deeper in my outer ear post dive but with the right care this is harmless.

The drysuit has been mentioned but even that is hardly an issue. Assuming you are in control, taking feet from pone to up shouldn't represent much more than a 6 foot swing and that won't cause a loss of control.

This may lead to your instructors guidance. Anytime we are goofing around we may let down our situational awareness. Should you ascend more than you realize a runaway ascent may commence. Diving wet with a readily dumped BC this is a quick fix. A drysuit has limited venting capability and time may not be on your side.

If you instructor is trying to evaluate your form (good for him!) he can't do so if you are diving like the court jester. Lapses in attention can also beat up on the environment or get you snared in lines. With practice there is a time and place for free form diving.

As for the regulator they all vary with orientation. The goal is to deliver air at a pressure equal to that surrounding your lungs. When you swim prone the second stage diagram which controls delivery is pretty close to that same depth. If you go head up vertical then your lungs can be a foot or so deeper than your second stage and the effect is like breathing through a snorkel while vertical with your mouth a foot underwater. In addition to the dead volume the simple work of breathing is apparent. Your chest must push out against 1 foot of water column pressure to expand and inhale. Most regulators are set to start delivering at about 1 inch of water column so this distance is significant. You should observe the opposite if you go feet up/head down. Breathing will be very easy and you may even have a gentle free flow on the end of each breath. Your training gear was better and/or more finely tuned.

Good questions!

Pete

 

[DivemasterDennis]

Actually, when you are properly weighted and you gear orientation is right, you should be in control of not only buoyancy but position . You should be able to hover horizontally, vertically, upside down,upright, on your back, on your face, etc. Every position will have it's use in seeing stuff, taking pictures, doing tasks, finding a buddy who drifted off, or otherwise. For peak performance you also need to be familiar with your equipment , so use of rental gear will be a limiting factor in performance. So, you know the solution- experience diving in quality gear that you use again and again. Time to go shopping!
DivemasterDennis

 

[g1138]

The only positions you should avoid are those that damage the environment or endanger you or your team. It depends on the dive.
I sometimes swim completely on my side to watch students, other times I'm belly up on ascent just to enjoy the view a little bit longer than usual.

I will say it is more challenging to control your trim and maintain buoyancy outside the "normal" body orientation. You just have to rely more on gauges and references rather than feel.

For your regulator, if you're inverted your first stage will be at a higher depth than your second stage. Therefore the pressure that the regulator has adjusted to for it's depth is slightly less than what it should be to be giving you. The result is the second stage not quite giving you ambient pressure.
Nothing wrong with inverting as long as you're getting enough air.

 

[garydemos]

Thanks everyone for the very helpful info. I am relieved that I can enjoy diving at any position, and the comments/considerations about being aware of other divers and the reef are noted. I am so excited about diving and can't wait to get out and do it again. I'm about to take the plunge on my own diving equipment as I am sure that I will be diving for many years to come.

 

[Bob DBF]

Your instructor just thought you were having too much fun and not paying enough attention to him.


Bob
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I may be old, but I’m not dead yet.

 

[spectrum]

For your regulator, if you're inverted your first stage will be at a higher depth than your second stage. Therefore the pressure that the regulator has adjusted to for it's depth is slightly less than what it should be to be giving you. The result is the second stage not quite giving you ambient pressure.
Nothing wrong with inverting as long as you're getting enough air.

This is wrong, the relationship between the stages is irrelevant. The relative discrepancy in IP amounts to a rounding error. It's the second stage to lungs depth relationship that governs the work of breathing.

Pete