Bouyancy control while ascending - What are the best practices?

[Islandheart]

While most and many of the suggestions above are good techniques to use during ascents, a few are less than safe.

- Never breath in deeply, ascent a few feet and then exhale. This is beginning to teach breath holding and should be avoided. Skip breathing is also a no-no.
*It only takes a few feet of over-expansion to cause DCI.

- Never use, "adding air to a BCD to begin or during an Ascent" so that you are not kicking. As has been said, "Riding the BCD or using the BCD as an elevator", can lead to serious injuries and SHOULD NEVER be suggested or taught to beginners.

Suggesting or "teaching" advanced techiniques to new/beginning divers, can and is hazardous. The "controlled buoyant ascent", is not a Skill in the Rescue Course. * If this is being "taught" in a Rescue class, it is outside of PADI standards and the Instructor/ DM should look at that and correct themselves.

Hopefully Proper Weighting, for the End of the Dive;
has been taught.

Proper Ascent Positioning;
Swim into a Feet Down, Head Up position. Left Hand holding the deflator up, with finger only on the deflator button (care should be given that fingers are not on the inflator button also) and the Depth gauage or computer in right hand in front of face so it can be monitiored..... then swimming up from a Neturally Buoyancy state, will keep you in control and safe.

If you are not controling your ascent, read "kicking", and something else is causing your ascent, you're setting yourself up for trouble.

Get control over your weighting before you dive (use a 500psi tank to check it at 15ft., get control over your total dive buoyancy by proper positioning and get control over your rate of ascent by how strongly you kick (ie you stop kicking and you should stop ascending).

For your own sake, DO NOT RIDE THE BCD during an Ascent !

my .02

 

[boulderjohn]

- Never breath in deeply, ascent a few feet and then exhale. This is beginning to teach breath holding and should be avoided.

Interesting.

Are you saying you don't teach students that they should control their buoyancy through the air in their lungs? What do you think of a beginning exercise like the fin pivot, in which students inhale, ascend a few feet, and then exhale? Do you teach that skill, or do you skip it because it is unsafe? How do you teach students to hover?

 

[00wabbit]

Thanks for all the advice. I get the jist of it.

I like the idea of dumping all the air at 30ft just in case some is left over.

I know I need to work on weighting. I am a big guy and I am pretty sure I was overweighted during the openwater dives. I could see how the bouyancy was harder to control. At 40ft I felt like I was putting in a lot of air to get neutral. Then as we slowly swam up the angled bottom towards 15-20 ft I started to elevate above the group and had to turn and kickdown while dumping air to slow my ascent.

I am hoping to go back to the quarry with the instructor or a dive buddy next week to work on weighting and bouyancy control.

 

[SnorkelLA]

Keep your SPG, or whatever you use to monitor depth at chest level, dump all air, very lightly fin until the depth meter reads anywhere +/- 2 ft from 15, but try to stay as close as possible, this is only a SAFETY STOP we're talking about, not a full on staged decompression . Try to control your buoyancy using only your breath at this point, it will make it hella easier. From there, after the stop is done, simply "go on up!"

 

[boulderjohn]

I like the idea of dumping all the air at 30ft just in case some is left over.

I don't, and several people have already told you why.

There are people who do advocate pretty much dumping all the air as soon as possible, even before starting the ascent. These are all people who have never done any cold water diving. You can do that if you are properly weighted in a thin wet suit, but if you are wearing a thick wet suit, that can be a disaster.

In a thick wet suit, you are not properly weighted during the dive. Because the suit loses so much buoyancy under pressure, the amount of weight you need in shallow water is too much for deeper water. Thus, when you are diving at depth, you are overweighted and must use extra air in the BCD to compensate. If you dump all that extra air early, you may lose too much buoyancy and be unable to hold your depth.

When I was a new instructor, I taught an AOW class with a young lady doing her first cold water dive in a 7mm wet suit and a hood. She was also the first person I had ever met who had been taught to dump all her air when she ascended, so I was surprised when she did that when we started our ascent. It took me 20 feet of rapid descent before I could catch her and stop her from plummeting into the depths.

 

[DukeAMO]

I have a closely related question.

I did my PPB classes with AL80s in two 5mm wetsuits, plus a hood, booties, and gloves, so I was wearing quite a bit of neoprene. I'm not a small person either (size L). I was able to descend with 24lbs of lead (slowly), and stay down through the dive and the safety stop at a depth of 15 ft. However, at a depth of about 5ft I got pulled up to the surface, even with an empty BC (and about 700 PSI in the tank). After that I wasn't able to descend again, so we swam back to shore at the surface. With 26lbs of lead, and 500PSI in the tank, I can exhale and slowly sink. So would the proper weighting for that configuration be 24lbs or 26lbs? In other words, is the goal to be able to hold a safety stop if you're already under water with 500 PSI, or is the goal to be able to descend again with 500 PSI? Is it worth carrying around the extra 2lbs of lead to avoid getting pulled up?

We ended up using 26lbs, but I'm curious what others would have done. I will say, the dive with 24lbs was easier. Until the end.

 

[mala]

I have a closely related question.

I did my PPB classes with AL80s in two 5mm wetsuits, plus a hood, booties, and gloves, so I was wearing quite a bit of neoprene. I'm not a small person either (size L). I was able to descend with 24lbs of lead (slowly), and stay down through the dive and the safety stop at a depth of 15 ft. However, at a depth of about 5ft I got pulled up to the surface, even with an empty BC (and about 700 PSI in the tank). After that I wasn't able to descend again, so we swam back to shore at the surface. With 26lbs of lead, and 500PSI in the tank, I can exhale and slowly sink. So would the proper weighting for that configuration be 24lbs or 26lbs? In other words, is the goal to be able to hold a safety stop if you're already under water with 500 PSI, or is the goal to be able to descend again with 500 PSI? Is it worth carrying around the extra 2lbs of lead to avoid getting pulled up?

We ended up using 26lbs, but I'm curious what others would have done. I will say, the dive with 24lbs was easier. Until the end.

there is about 6lbs of gas in an ali 80 that you will use during the dive.
at the start of the dive you should be 6lbs heavy so that at the end of the dive you will be correctly weighted and able to stop at any depth.
if your buddy needs help at the end of the dive its no good being stuck on the surface.


2 x 5mm wetsuits?

sounds like a drysuit was needed.

 

[DukeAMO]

if your buddy needs help at the end of the dive its no good being stuck on the surface.


2 x 5mm wetsuits?

sounds like a drysuit was needed.

Hm, good point on being able to get back down if your buddy needs help. Why didn't I think of that?

Drysuit - hah. Maybe someday.

 

[boulderjohn]

Is it worth carrying around the extra 2lbs of lead to avoid getting pulled up?

We ended up using 26lbs, but I'm curious what others would have done. I will say, the dive with 24lbs was easier. Until the end.

Diving with that much neoprene is always more difficult during the dive because you have to be overweighted at depth. Therefore, the less weight you have during the deep part of the dive, the better you will feel. In an ideal universe, you would hand off some of your weight once you were at depth and get it back when you ascend. Unfortunately, that isn't gong to happen. You therefore need to have enough weight to complete the dive--and I would say complete is with less than 500 PSI because you never know what might happen.

That is one more reason to prefer a dry suit--constant buoyancy.

 

[chrpai]

Proper Ascent Positioning;
Swim into a Feet Down, Head Up position. Left Hand holding the deflator up, with finger only on the deflator button (care should be given that fingers are not on the inflator button also) and the Depth gauage or computer in right hand in front of face so it can be monitiored..... then swimming up from a Neturally Buoyancy state, will keep you in control and safe.

Sounds like the PADI world. I perfer the horizontal trim position with my computer / depth gauge mounted on my right wrist and my hands free in the event that I need them. I also like making nuckle on nuckle contact with my buddy while maintaining eye contact and same depth. I only go verticle after the safety stop and only when I'm concerned about boat traffic.