Trouble w/ inversion at Safety Stop

[rongoodman]

I usually start off by going a little head down, and with a back kick or two, start to rise. This puts the expanding air in the bottom of my wing, making it very easy to dump. If things get a little too fast, I'm in a position to kick down and slow myself. I'm at a loss to understand what's happening to the original poster. I dive a SS plate and typically with 2/3 of any additional lead on my belt and 1/3 on the upper tank band I feel comfortable flat in the water.

Every reference in the PADI OW course is to slowly swim up, nothing about drifting up. I tell my students they need to take the stairs - no elevator rides.

I seem to remember something about a "controlled buoyant ascent" in my PADI OW course, but that was 12 years ago.

 

[Kyle0692]

I fin very little and around the safety stop depth I get vertical and dump all the air I can from my shoulder vent until I see no more bubbles. May be getting some trapped in the lower corners like you say.

 

[JackD342]

UCPA is not a diving association. It is a non profit French organisation, which makes sports holidays of all types, that includes diving as well.

UCPA - Wikipedia

So I did find links that say they offer scuba training. Do you know if their cards say UCPA, or are they using one or more other training organizations? And if that is the case, do the videos they are producing align with that agency or agencies, or do they sometimes contradict?

 

[Kyle0692]

One question I have is what exposure protection are you wearing? If you are wearing a thin wetsuit and have to add air to your BC you may be over weighted also an aluminum cylinder is more buoyant on the bottom so moving it up may help or distribute more weight to the hips not adding weight just distribute it different. Ankle eights could help depending on what type of fins you are using "negative or positive".

5 MM wet suit is what I wear

 

[BlueTrin]

So I did find links that say they offer scuba training. Do you know if their cards say UCPA, or are they using one or more other training organizations? And if that is the case, do the videos they are producing align with that agency or agencies, or do they sometimes contradict?

According to this page (you can use google translate)
séjour Plongée : découvrez les centres UCPA

They deliver FFESSM certificates in France, which seems to be a French diving association. Apparently you can get PADI certificates if you go in UCPA centres outside France.

So although I am not 100% sure, I thibk they are probably using other agencies certifications (I.e. FFESSM and PADI) rather than their own rules. Don’t trust me 100% on this one: I am French but have lived in the UK all my adult life so I know nothing of UCPA dicing activities.

On another topic I found this video because you mentioned BPW:

 

[Seaweed Doc]

This is tangential, but has me curious. Why insist on being horizontal at the safety stop, assuming you're in deep water? Most situations I've been in like that the vertical orientation seems safer. I can keep an eye on my buddy and the group, quickly scan up to look for boats, and scan down to see for sharks looking for a snack. (Well, maybe not that last one.)

If I were swimming to shallows for a beach exit, of course horizontal is what you want. Enjoy the shallow water critters. For that reason getting your trim worked out can help.

 

[BlueTrin]

This is tangential, but has me curious. Why insist on being horizontal at the safety stop, assuming you're in deep water? Most situations I've been in like that the vertical orientation seems safer. I can keep an eye on my buddy and the group, quickly scan up to look for boats, and scan down to see for sharks looking for a snack. (Well, maybe not that last one.)

If I were swimming to shallows for a beach exit, of course horizontal is what you want. Enjoy the shallow water critters. For that reason getting your trim worked out can help.

Well the reason I asked JackD to clarify is that when I had a jacket I was trying to be slightly negative at stop or neutral and I was vertical (unless I come back from a shore dive like Seaweed Doc sais above)

I know people who can ascend vertically along a line but it seemed easier to me to ascend vertically along a line or when holding a DSMB in open water.

When I got a BPW recently I ascended in the manner of this last video but that was because it felt more natural to stay horizontal with a wing in my back.

I will ask an instructor who has a BPW next time I go to the club. If anyone has good answers on these topics I am all ears though

EDIT: for clarification when I was using a BPW I wasn’t initiating ascent by inflating but just by keeping my lungs a bit fuller like someone described below.

 

[johndiver999]

The op sounds like he is ascending perfectly. Of course padi teaches to stay slightly negative and fin up, but once
You are skilled in buoyancy control, there is absolutely no problem with ascending ever so slightly bouyant.

This is especially so for the deeper portions of the ascent. In addition, if your goal is to ascend in a horizontal trim position, I don’t know how you can efficiently kick up like that.

The horizontal position generates drag as you slowly rise up or down, so it helps inhibit excessive speeds.

A good test to confirm that your are ascending in control
(But are still positive) is to exhale forcibly and more completely than normal. If a full exhale completely stops your ascent, then you are in control. If you are still floating up slightly, then inhale and dump a little from the bc.

If you inhale fully and your ascent stops, then you are a tiny bit heavy and you can drop your feet a little and give a kick and and move up a foot or two. I prefer this, than to add air to the bc.

I didn’t watch the video, maybe that is what they say. The real goal is to maintain your buoyancy imbalance to a magnitude that is less than the shift from normal breathing. If the imbalance is maintained within that envelope then you are never out of control, because manipulation of lung volume is sufficient to immediately arrest the change in depth.

For the last 10 feet of ascent, it may make sense to get vertical and stay negative and kick slightly so you can better see the surface and can be more aware of potential obstacles.

 

[MichaelMc]

A first, bad, ascent option is adding air to your BC, like an elevator, to somehow ride that up while venting. Edit: Risky as your are adding BC air that will just have to be dumped, making overcompensation, and runaways, more likely.

Gently finning up is a second option, and far preferable to the first, also with BC venting when needed. Its strong preference over option one is a likely cause for any Padi emphasis, as option one is a bad idea.

A third option is to shift slightly the normal cycle of your breathing. Your breath normally cycles you between slightly buoyant and slightly negative, but on average neutral. By shifting it to be slightly buoyant more often, you drift up gently, which is the rate you want. Then periodically vent BC air as needed so that you would return to neutral buoyancy if you resumed an even, balanced, breath cycle. It is important to emphasize that you are *not* holding your breath! You just spend more of it with fuller lungs and less of it with emptier lungs. You remain horizontal when you initiate ascent and for all of it except the last few feet below the surface. All very different from a buoyant emergency ascent.

Normal tidal volume, how much we inhale and exhale for a relaxed breath, is +-0.5 pints so 1 pound range total for men and women. Men have a 7 pint inspiratory reserve above that and a 2 pint expiratory reserve below that. Women have +4.5 pints and -3 pints. So there is a large buoyancy range to your lungs while staying far away from full inflation. Just shifting the timing of your inhale/exhale cycle, and not even the range, will make you more positive and drift you up. That is all you need.

Here is a rather nice GUE video on buoyancy. It describes using lungs as part of your buoyancy control, though not so much the details of ascent. GUE is one of the premier technical diving organizations.

Horizontal trim at SS helps increase vertical drag and make depth control easier at a depth where it is the hardest. It also makes horizontal movement easier by reducing horizontal drag and making that where your fins point. We want slow vertical movement, but might want to move to or away from our buddy for various reasons.

OP, a weight belt might help move lead lower, depending on your setup.

 

[elgoog]

Close to 90, not more. I will try stretching out next time and see if that helps me.

If possible, get someone to video, photograph or watch you - you'll be surprised how different your leg positioning actually is compared to what you think. When I was struggling with drysuit ascents I was convinced my legs were at 90deg when, in fact, they were touching my butt.

Why insist on being horizontal at the safety stop, assuming you're in deep water?

Much easier to control buoyancy and not shoot up/drop down - when you're horizontal, your body's surface area is much greater, creates a ton of drag and ascents+descents are far more controlled. This may not be as noticeable in light rigs (thin wetsuit, single AL tank) but is very important in drysuit, doubles, etc. Once you get the correct position, it's very easy to look around and see you buddies and you can do a quick sideways roll to look up if you need to.

EDIT: @MichaelMc and I typed at the same time. So, yeah, what he said