What if... [loss of buoyancy question]

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Alessandro Calello

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Hello guys,

I was wondering what if your jacket brakes while you are under water? what you are supposed to do then? if it doesn't pump up anymore? you just remove your weights and try to go slowly up?

Thanks!
 
Do you mean if your BCD loses buoyancy? This should have been covered in your OW class, but here's my opinion: Ditching weights at depth carries some risk, so it shouldn't be your first, instinctive reaction. OTOH, ditching weights at the surface is only harmful to your wallet, so the barrier to ditching at the surface should be rather low. Life is worth infinitely more than money. It all depends on the situation, though.

Since I'm always diving within no-deco limits, going to the surface is always an option. In case of my BCD losing buoyancy, there are several scenarios:

  • If I'm diving in my home water, I'm diving dry and will always have redundant buoyancy¹. If I'm shore diving at a benign site, with a hard bottom at rec depths, I might continue my dive using my DS for buoyancy. That would only happen under very safe conditions, though. I've done this.
  • If I'm diving dry on a wall or another site where loss of redundant buoyancy would be a hazard factor, I'd use my DS for buoyancy, surface and abort the dive. My buddy has done this. If I'm unable to establish sufficient buoyancy on the surface, I'd probably ditch my weights.
  • If I'm diving wet, at a site with a hard bottom at safe depths, I'd first try to surface in a controlled manner by swimming up without ditching my weights, and abort the dive. If I'm able to surface without ditching weights, I'd probably ditch my weights at the surface. If I'm not able to surface without ditching, see below.
  • If I'm diving wet on a wall or other sites where loss of buoyancy would be an acute hazard, and I'm not immediately able to start my ascent by swimming up, I'd start ditching my weights. This would probably lead to an uncontrolled ascent ("uncontrolled" meaning I wouldn't be able to stop it before I'm at the surface), but with the amount of weight I need while wearing a moderately thick wetsuit, the ascent would probably not be too fast. I'd of course make sure to open my airways on my way up, and I might try to flare out to slow the ascent as much as possible. If you carry so much weight that ditching at depth turns you into a Polaris missile, you're either overweighted, or you should seriously consider getting a drysuit instead of using several layers of thick neoprene.


¹ This advantage of drysuit diving is IMO often undercommunicated, but that's a different discussion.
 
Hi Storker,

Thanks for your reply, but I have some questions:

1) Diving dry you mean with a dry suit right?
2) Diving wet instead you mean with a wet suit right?
3) What you mean with DS?
4) With my questions I mean if you are diving and your BCD brakes and you are unable to pump air in it to go up, what's the best thing to do? will you start going down? is it better to ditch your weights and try to go back up?
5) Why it makes difference where are you doing the dive if it brakes?
6) With diving on a wall you mean a wall of rock where you cannot see the bottom?
7) With diving in your home water you mean the place where you usually dive and you know well?
8) What you mean with "I'd of course make sure to open my airways on my way up, and I might try to flare out to slow the ascent as much as possible" what you mean with airways? and flare out?

You answer my question anyway in certain ways, but still I'm a bit confused about what to do in this kind of situation, I'm an OWD but I did my course 9 years ago, I just recently start my AOWD and I'm studying so I start to have questions or doubts about some matters and I know that on this community there are nice people like you who knows so much about everything and can help me.
 
1) Diving dry you mean with a dry suit right?
Yes

2) Diving wet instead you mean with a wet suit right?
Yes.

3) What you mean with DS?
DS = DrySuit. WS = WetSuit.

4) With my questions I mean if you are diving and your BCD brakes and you are unable to pump air in it to go up, what's the best thing to do? will you start going down? is it better to ditch your weights and try to go back up?
As I said, it depends. Are you able to swim up without assistance from your BCD? If I can do that, I'd rather not ditch weights at depth, but I might well ditch on the surface. If I can't swim up, it's time to start ditching, preferably in increments if the situation makes that possible (you don't want to shoot quickly to the surface, and that can happen if you ditch a large amount of weight)

5) Why it makes difference where are you doing the dive if it brakes?
Because where I am makes a difference if I can't swim up or keep my depth without much trouble. On a shallow shore dive, I won't be in immediate danger if I hit the bottom and I can - at least theoretically - walk up along the bottom. On a wall dive, I might start descending to dangerous depths.

6) With diving on a wall you mean a wall of rock where you cannot see the bottom?
Yep. You dive along a more or less vertical wall, and it may be rather deep below you. Losing buoyancy in a situation like that is quite different from losing buoyancy over a flat bottom at 10m depth.

7) With diving in your home water you mean the place where you usually dive and you know well?
I mean in the region where I usually dive, with the water temperatures I usually experience.

8) What you mean with "I'd of course make sure to open my airways on my way up, and I might try to flare out to slow the ascent as much as possible" what you mean with airways?
Do like they taught you in the emergency ascent exercise during OW trainnig: Open your mouth, look up, don't hold your breath, make an "aaahhh" sound.

and flare out?
Go somewhat horizontal, spread your arms and legs to provide maximum surface towards your direction of travel. That will slow down your ascent. Slow is good, especially while ascending. Lower risk of barotrauma that way.

You answer my question anyway in certain ways, but still I'm a bit confused about what to do in this kind of situation, I'm an OWD but I did my course 9 years ago, I just recently start my AOWD and I'm studying so I start to have questions or doubts about some matters and I know that on this community there are nice people like you who knows so much about everything and can help me.
Talk to your instructor about this. If I were in your situation, I'd check on the quality of the AOW class you'll take. Is it a minimum time, minimum cost class, or is the instructor willing to use more time and provide some additional/remedial instruction/tutoring (that will probably cost more)? Since you obviously haven't dived much since your OWD and that was nine years ago, would it be better for you to take a refresher course or re-do your OW before going AOW?
 
1) So your DS gives you already some buoyancy?
2) So if your BCD brakes there is no way for you to remain underwater, you can always come up? even with the bottle on your back?
3) If it happens next to a wall there is a chance for you to don't be able to get to the surface anymore?
4) You wrote "Do like they taught you in the emergency ascent exercise during OW trainnig: Open your mouth, look up, don't hold your breath, make an "aaahhh" sound" but nobody taught me anything like that.
5) Yes my instructor is willing to do more dives to make sure I understand everything again, I asked him if it was better for me to do again my OW and he told me that I can dive, there are only some matters which I need to learn again.
 
1) So your DS gives you already some buoyancy?
Yes. If I want to, I can do a whole dive never filling any gas into my BCD underwater. Some drysuit divers use their BCD for buoyancy only on the surface and their DS for buoyancy underwater, but that's another can of worms...

2) So if your BCD brakes there is no way for you to remain underwater, you can always come up? even with the bottle on your back?
I sincerely hope so. If I can't swim up, I'm either overweighted or using the wrong equipment. In any case, I should be able to ditch weights if I can't swim up.

3) If it happens next to a wall there is a chance for you to don't be able to get to the surface anymore?
Yes, if I start an uncontrolled descent and can't stop it, I won't stop until I hit the bottom. If that bottom is at 100m, I'll probably die.

4) You wrote "Do like they taught you in the emergency ascent exercise during OW trainnig: Open your mouth, look up, don't hold your breath, make an "aaahhh" sound" but nobody taught me anything like that.
That's bad, because if I remember correctly, that's a required exercise in OWD class. It's too late to ask for a refund of your fee, but you should seriously learn about proper procedure in case of an uncontrolled ascent. If you hold your breath on ascent, you might well end up with an embolism. That might well kill you.
 
1) I think some drysuit use air as insulation layer between your body & the drysuit. That adds buoyancy.
2) You have fins on you, so you can try to swim up with them to counter the weight that drags you down.
3) Same as 2). There was an instance where a downcurrent dragged me down stronger than I can swim up. It was quite scary to watch my exhaust bubbles going down to the abyss. I just grabbed on the rock wall & started to rock climbing underwater.
4) Air in your lung would expand as you come up, doubles the volume for 10m (2 bar absolute pressure) to the surface (1 bar absolute pressure) of ascend. You want to let the air out to prevent blowing up your lung.
5) Good move.
 
I think some drysuit use air as insulation layer between your body & the drysuit. That adds buoyancy.
All drysuits have "a layer of" air between the suit and your body. Usually, that air is held in your undergarments. That's what provides insulation. When you descend, that air compresses, and your suit becomes too tight. That's what we call "suit squeeze". If you don't add air to your suit, you might become so shrink-wrapped that you can't reach your inflator. That's bad. So, a drysuit diver gradually adds air to the suit as they descend to avoid squeeze and gradually vents air from the suit as they ascend to keep neutrally buoyant. For a normal single tank rec dive, a properly weigthed diver won't need to add much - or any - air to their BCD as they ascend or descent; the air in the BCD is only needed to offset the weight of the gas you carry, and it's slowly vented during the course of the dive to compensate for your increased buoyancy as you consume the air in your tank.

In any case, since the drysuit is watertight and connected to your gas supply, it can be used for redundant buoyancy in case your BCD malfunctions. I like that; it gives me an extra layer of safety at sites where a sudden loss of buoyancy may have nasty consequences.
 
Hi Alesandro, if you are weighted properly and you really only have the weight you need, you don't need a BCD. You will be a tiny bit heavy but you can still just swim up.

I have done a bunch of dives in a 7 mil suit without a BCD... it's no problem, just make sure you've done your weight check properly!It just sucks when you have to wait for a boat while on the surface. Maybe ask someone to help you with the weight check.
 
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