What Happens when you Take your BCD off at Depth

[IncreaseMyT]

The few times I had to remove it during training we just sling it around and lay the bcd on our knee. This worked fine on the bottom. The one time I had to do it at depth with no bottom I slung it around and wore it on the front. But none of the times did I suddenly become inverted. Granted I was not in any suit. Just a rash guard, and I’m only 180lbs and 6’0 so I’m on the slimmer side as well.

Im talking about being all the way out of it with it on the bottom and no air in the BCD. Just holding on to a shoulder strap with my left hand, at least thats how I do it, so I can adjust rig with the other hand. I specifically hold my left shoulder strap, because I can use my other hand to adjust the air in my BCD before putting it back on. I also have a SST1 here.

This is also the only position I could easily dump my trim weights.

 

[CuzzA]

Being able to remove your rig at depth is an essential skill. Whether simply to adjust or de-tangle yourself. I do not dive with integrated BCD ballast as it gives you a disadvantage of your body becoming buoyant and makes working on the rig harder. Some simple designs stand the test of time. A rubber weight belt and hard lead is one of those designs. Not to mention I despise lifting a guy's rig over the gunwale with integrated ballast.

I also think some of today's BCDs are poorly designed with multiple buckles and straps that needs to be undone to get out of the rig. The crotch strap is one I ditched early on (I don't have a scooter), and more recently I took off my chest strap. They're just not needed if your rig is balanced and setup right.

As for taking your rig off for an emergency surfacing ascent, it all depends on depth. Shallow? I don't see the need. Deep? It's hard to say. There may be a case to be made for ditching and going as the BCD and tank create drag. In fact I recall the documentary Black Coral and the divers talking about the topic. They actually mock today's training a bit by pointing out if you're out of gas, 170 plus feet deep, ditch everything, blow and go... and pray.

For some perspective, 100 feet deep is the equivalent of a ten story building. To test what a 100 foot OOG ascent would be like, exhale and then start walking up the stairs of that ten story building. Setting other factors like gravity, buoyant exposure protection or potential gas in your wing aside, it's still gonna suck. Best to not run OOG.

 

[Miyaru]

Wearing a 3mm wetsuit, I can dive in seawater with just an AL80 & regset. Over 90bar the tank will bring me down, below 90bar the tank will start pulling me up while I'm still in control. No weights required.

At depth I remain neutrally buoyant, because my lungs don't shrink. I know this because my lungs don't pop out of my mouth when I'm in an airplane at cruising altitude.

 

[IncreaseMyT]

Back in the days of horse collar BC's (or no BC at all) we would routinely take our tank off, leave it outside a lobster cave, and slither in breathing off our 20-foot primary hose. Today (and excluding weight integrated BCD's), if one is weighted properly, there shouldn't be any air (or just a few squirts) in your BC at depth.

 

[johndiver999]

Once again Mr T. seems to exhibit a poor grasp of physics. If a person wearing no gear sinks at the surface while their lungs are filed, then they will also sink when they inflate their lungs at depth while on scuba. No meaningful difference at all.

If you are big and fat, it is hard to imagine anyone actually being able to just sink in the ocean, but there are some people who do. In freshwater, it is much more common to have people who just won't float when holding a normal volume of air in their lungs.

In any regard, a normal person wearing no wetsuit and no weightbelt, is not going to rocket to the surface if they remove their scuba unit and all ballast. They will probably be within 2- 5 lbs positive, which is not that difficult to offset by finning if they desired.

 

[IncreaseMyT]

that difficult to offset by finning if they desired.

In the inverted position of course!! Ding ding, thanks for proving another point.

 

[CuzzA]

In freshwater, it is much more common to have people who just won't float when holding a normal volume of air in their lungs.

I think it's much more common that an average person would float. Floating on your back and maintaining full lung breathing is the basics of learning to swim in a pool.

 

[IncreaseMyT]

So now you can start to see why I have arrived at this plan through practice and pondering. I have dropped 4 pounds, I have taken off my BCD and I am inverted. I have already just went up 8 feet because I am now inverted, plus I am beginning to rise because I dropped 4 pounds.

I also am now 8 feet higher than my BCD and more buoyant so I am dragging my BCD up. Do I have air? I pull my left hand close to me, and now have easy access to my SS1, I grab it and have air! All is good I am letting a little air out of my BCD to compensate for the dropped weights and get my ascent under control.

Ok replay, diffrent scenario, I grab the SS1 and there is no air, I quickly pull the bottom tabs on my trim weights since I have easy access to them, now I have just dropped another 6 lbs and am ascending quickly, I have no air still and at it this point my BCD is of no use to me, I can now let go and freely ascend to the top and pray I don't black out at 15 feet, at least I know if I do I am not entangled in a BCD so I will probably end up floating on my back unconscious.

Ok another scenario, I have no air, take off my BCD and still no air, I am already ascending cause I pulled the rip cord on my Zeagle immediately and dropped 4 pounds, plus I am already up 8 feet cause I am inverted. I look at my rig and somehow the reg is busted, or off. Yes at this point I would breathe off the tank.

Lastly, I see air shooting out of the side of me, I am at 120 feet. I immediately drop weights take off my BCD and begin to ascend. I have air! This is great. I am ascending. All the sudden, no air again, but now I am at 70 feet. I ditch the BCD at 70 feet instead of 120 and live to see another day.

I can sit here and do this all day, there are a million reasons, for me, to do it this way when I am solo.

 

[caruso]

For some perspective, 100 feet deep is the equivalent of a ten story building. To test what a 100 foot OOG ascent would be like, exhale and then start walking up the stairs

Problem with that analogy is that walking up 10 flights is a heck of a lot more exertion than ascending from depth and doing some kicking. A better analogy might be swimming the length of a 40' pool and back on one breath which is within the realm of possibility for those on reasonably good shape.

 

[IncreaseMyT]

And remember you're not going to breathe at depth, you're not going to want to. I don't at least. So even if your on your on an empty breathe you still got a couple minutes before you pass out, but the problem is, you're probably gonna pass out from the quick ascent when you get to 15 ft. That increases the chances, so does looking up, so if your ascending you want to look straight ahead and pray nothing is above you.