Fear of uncontrolled ascent

[chickweed]

My daughter and I just completed the confined portion of PADI OW training and we will be heading to Destin FL for our four check out dives over Labor Day weekend. When we were doing the confined dives, there were a few times that I slightly over-inflated my BC and it took several feet to get things back under control, so in the pool, I was back at the surface in no time.

So, as we head to do our dives (in the ocean), I find myself being anxious about what if I (or my daughter) get into an uncontrolled ascent. I'm curious if my fear is rational and I'm also curious if there are techniques (presumably the first thing to do is dump all air in the BCD, right?) to arrest a rapid ascent?

 

[windapp]

This is probably the one fear in diving that is not bad to have. If you ever have a panic, it may counteract the "I need to surface right now" instinct.

There are only a couple of causes of an uncontrolled ascent for a beginner diver(other than a wrong button error). The most important thing is to keep your airway open so you don't get a lung overexpansion injury.

The first is losing your weights. All you can do in that situation is dump all the air in your BCD, and fan out our arms and legs to slow your accent.

The second is a stuck inflator value. You were taught in the close how to remove the inflator hose from your BCD under the water. If you are practised at this, you should confident in your ability to overcome this situation.

Other than that, just don't pick up any heavy objects as dropping them could cause you to have a sudden uncontrolled ascent.

 

[Agility]

The first thing is to exhale, which is counterintuitive.
If you are head up in this situation make sure to keep your fins steady, do not kick, as kicking will push you up.
Then dump some air out of your BC.

Staying horizontal will slow your ascent by causing more drag.
Spreading out arms and legs (as seen with parachute jumpers) slows you down, too.

The earlier you correct your upward movement the better, so do not wait once you have started your way up but exhale immediately.

 

[Teller]

Stay neutral during the dive and use your lung volume. Dump air during the ascent as the gas expands.

 

[g1138]

Staying horizontal will cause more drag and slow your ascent.

I think your fear chickweed comes from not having good control over your BC input and not having an intuition on buoyancy control, which will both come with time and practice.
Try putting air into your BC in tiny spurts. Just tap the button once or twice when you first descend. Wait a few seconds and breath normally to see how buoyant you are. If you need more air in your BC, add it in in tiny spurts. It helps to add air on a long descent so you're not crashing to the bottom.
There will always be a delay in how your buoyancy feels and acts when you're adding or removing air, so it's good to wait for around 2 seconds before adding more air.

Weighting yourself properly makes all of this a whole lot easier as well.

 

[diversteve]

Not saying all checkout instructors do it but typically as new divers you'll be slightly overweighted to begin with. So an uncontrolled ascent will be less likely to happen.

After you've dove for a while and have your weight dialed in you'll find that at depth you'll likely vent all the air out of your BC and use only your breathing to regulate your trim.

Just remember to vent on ascent since even the smallest amount of air in the BC will expand as you go up. Should it start to happen, just hold the inflator overhead and press the deflate button - you'll stop in a hurry and can recover.

Also it's actually much harder to control your buoyancy in a 10' pool than it is in 40' of ocean. You have less time to react and vent/add air as needed.

 

[windapp]

Not saying all checkout instructors do it but typically as new divers you'll be slightly overweighted to begin with. So an uncontrolled ascent will be less likely to happen.

Exactly the opposite. If you are overweighted, an uncontrolled ascent is more likely to happen. Since you have more air in your BCD, there is more to expand as you ascend, and you have to dump air more frequently to control your ascent.

After you've dove for a while and have your weight dialed in you'll find that at depth you'll likely vent all the air out of your BC and use only your breathing to regulate your trim.

Only in the warmest of water.

 

[Glenn08]

I see free-ascent theory and training is still a contentious subject. I was taught to 'pant' on ascent to prevent small airway closure, and possible lung over-expansion and injury. 'Blow-and-go' was not the favored method.

 

[boulderjohn]

As windapp said, being overweighted makes an uncontrolled ascent more likely, not less likely. That is the irony in the fact that when people find themselves dong uncontrolled ascents as new diver, the reflex act is to give them more weight, which only makes it worse. The less air you have in the BCD, the easier it is to control your depth through inhaling and exhaling.

Believe it or not, it is more difficult to control your buoyancy and have uncontrolled ascents in the pool than in the ocean. That is because of the depth. If you remember the instruction you received regarding the effects of pressure on the compression of gases, you will recall that a balloon (or BCD) with a certain amount of air in it will compress to half its original size in the first 33 feet of sea water, but it will then only compress to a third of its original size in the next 33 feet. That means that every foot of change in depth has a much greater effect on your buoyancy in shallower water than in deeper water.

If you have the right amount of air in your BCD to balance the weight you are carrying, you will have a range of depth in which you can control yourself totally by your breathing. If you are properly weighted, that is a pretty large range. Consequently, if you feel yourself starting to rise, simply exhale to go back down, as was suggested above. If you are having trouble doing this, then you probably don't have the right amount of air in your BCD, and you should adjust.

 

[diversteve]

Exactly the opposite. If you are overweighted, an uncontrolled ascent is more likely to happen. Since you have more air in your BCD, there is more to expand as you ascend, and you have to dump air more frequently to control your ascent.

She's more likely to stay down with more weight. Thus the chance of it happening initially is smaller.What part of this in my post didn't you read?

Just remember to vent on ascent since even the smallest amount of air in the BC will expand as you go up.

Only in the warmest of water.

Ever been to Destin FL? In Sept.? Avg. Water Temp: 84°
Teller seems to agree also.