Uncontrolled ascent today from 40ft - advice sought

[FPDocMatt]

For more information, take a peek at my series of (9) articles about buoyancy: Scuba Buoyancy Masterclass - Buoyancy Control for Scuba Divers

In particular - Article 3: Scuba Buoyancy Masterclass 3of9 - Achieving Great Buoyancy Control

Gee, I wish I'd had you for my instructor. They teach you to float on the surface at eye level with an empty BCD and a full breath, but they don't say, "Now exhale. You should slowly begin to sink." That really clarifies what you're trying to achieve. They also don't say, "Now add 5 lbs to compensate for an empty tank".

Both the instructors I dived with during my OW and AOW dives were like, "Oh no, there's no way you need that much weight". (I'm 5-8 and weigh 150 lbs.) But each time, I couldn't descend simply by exhaling with an empty BCD, got stuck on the surface, and they had to add weights to me. I think one principle here is that, whatever technique you use for determining your weighting, eyeballing by the DM is not the way to do it!

 

[rongoodman]

Ok, so I understand that ascending horizontally will increase drag - and will put me in the position of being able to assist other divers if there is a need...I'm picturing a bunch of Ascending scuba divers looking like a pack of DEscending sky divers!

Don't forget being able to kick down.(I know I can stay on the bottom with my 30# wing completely inflated, just by finning, because Ed Hayes made me do it!) It's a good visual, though. If you look at the typical sky diver picture, not only are they flat, but their legs and heads are up and they have that little bit of an arch in their backs which makes the whole thing work. Once you get that posture down, learning the frog kick(and the back kick, and the helicopter turn) will be much easier.

 

[farsidefan1]

One thing I have not seen mentioned (probably because if you follow the other suggestions this won't be necessary) is that you should learn to use the other vents on your bc. If you need to be kicking down to stop the ascent you can do this and vent your bc at the same time (in case air in your bc is the cause of your uncontrolled ascent). Your bc has multiple vents. I'm sure one of them will work with your butt up / head down. Just get more familiar with your gear and you can worry less about the risk of uncontrolled ascent.

 

[bl6394]

Gee, I wish I'd had you for my instructor. They teach you to float on the surface at eye level with an empty BCD and a full breath, but they don't say, "Now exhale. You should slowly begin to sink." That really clarifies what you're trying to achieve. They also don't say, "Now add 5 lbs to compensate for an empty tank".

Both the instructors I dived with during my OW and AOW dives were like, "Oh no, there's no way you need that much weight". (I'm 5-8 and weigh 150 lbs.) But each time, I couldn't descend simply by exhaling with an empty BCD, got stuck on the surface, and they had to add weights to me. I think one principle here is that, whatever technique you use for determining your weighting, eyeballing by the DM is not the way to do it!

I'll second that!!! When I first transition to doubles - the LDS owner who sold me the kit suggested I start with about 16 pounds of weight. (Steel HP100's, steel BP, 45 pound wing, dry suit.) Good thing I was near a platform - cause with that much weight - I sank like a rock - and the wing didn't have enough buoyancy alone to float my kit...

It takes some work to figure out what sort of weighting a balanced kit requires - but the benefits of not being under or over weighted are well worth it. Likewise, the effort to dial in your buoyancy and trim so that you can remain neutral in a horizontal position and control your ascents / descents without using your power-inflator like an elevator button will make you a much better diver - whether your interests are recreational or technical.

Just my 2 psi worth.

 

[dumpsterDiver]

Ascending horizontally requires the diver to be
neutrally buoyant and have the capability to fine-tune variation between positive-neutral-negative buoyancy using breath control. In turn, this requires precision weighting.

I wouldn't dispute that horizontal ascents aren't harder - but they do foster and promote a very high degree of buoyancy control. Whilst initial development is harder, the long term benefits are much more substantial.

Conversely, using vertical ascent techniques ultimately enables the novice diver to compensate for poor buoyancy by using the legs. That compensation reduces the need for perfected weighting, breath control and precision control of the BCD. That makes things easier... but also serves to retard the divers overall 'feel' for buoyancy and ability to perfect their technique and weighting.

If a diver has perfect control of their buoyancy, they can ascend in ANY position.

PADI teaches feet first descents, exhale and then sink down etc... This is a retarded way to dive for an experienced diver, or one who needs to pull down an anchor line in current or one who needs to descend quickly or vertically in a current with no visual reference.... HOWEVER, it is fine for TEACHING people how to dive when they are first learning.

I taught my kids to freedive first, so they were never taught to do feet first descent.. just flip over and kick down...(the way REAL divers do)..

You seem to be implying that different amounts of ballast would be necessary for a vertical versus horizontal ascent... that makes no sense to me at all?

However, I STRONGLY believe that performing ascents (especially without a rope or visual reference) can be difficult for new divers. They are more likely to be in control, and have better visual orientation and are therefore actually SAFER, if they FIRST learn to ascend in a vertical orientation, while striving to maintain an ever so slight negative buoyancy.

Trying to ascend face down, spread out, DOES require the diver to be ascending in a buoyant condition (for at least portions of the ascent) or they would NOT ever ascend.. they would just hang there...

I have no problem with experienced divers choosing to ascend "like a sky diver", but it is not the way to learn the skill.. in my opinion.

Buoyancy control is really learning to BALANCE an unstable equilibrium. It can be demonstrated, but it is never really taught.. the student needs to LEARN to balance themselves... just like you can't TEACH a kid to ride a bike,, they eventually just have to learn to balance it.

 

[DivemasterDennis]

To summarize and simplify, focusing on the original questions raised and the wealth of information posted, here is what we have:
1. It is best to be properly weighted. It is better to be "a little" overweighted than to be a little underweighted.
2. On the facts stated, missing the safety stop, though not good, was not disastrous. Be properly weighted so you can achieve a hover at 15 to 20 feet without effort.
3. A proper weight check is an important part of gearing up. When doing your weight check, remember that a depleted tank is lighter than a full tank. Weight accordingly.
4. If you felt "heavy" or "light" on a dive, and make weight adjustments, have them be modest. dropping 20% of you weight is not "modest."
5. Keep a log of every dive including equipment worn and weight worn and note the buoyancy issues. Soon you will have a "weighting chart that will serve you well, and which you will keep updated.
6. Review what you were taught about slowing a runaway ascent. That includes vertical head down fin kicks, upright "arm pulls", holding a line (or anything else at hand) if one is around, being close to your buddy so assistance is possible, etc. In fact, regular review and remediation of all dive skills is useful. So is experience. Be an active diver!
DivemasterDennis

 

[spectrum]

IrishPaul,

You made a significant on the fly adjustment and cut yourself short. There are ways to get a handle on your approximate weight before you commence a dive and the best evaluation will be at the end of the dive with you cylinder contents at the low end, ~500 PSI. Here is my long answer.

Pete

 

[XS-NRG]

A properly weighted diver should be neutrally buoyant, with an empty BCD, during their safety stop at the end of the dive (with near-empty cylinder). In this instance, there will typically be little-no air in the BCD to expand on the ascent. Hence, there is nothing to lose control of.

Excellent description/comment!!!

I too would love to get instruction from you. I'm hoping to goto Asia at some point to do some diving. I think I could easily learn a thing or 2 from you :cool2:

 

[Ricky B]

I taught my kids to freedive first, so they were never taught to do feet first descent.. just flip over and kick down...(the way REAL divers do)..

Head-up descents make it easier to clear the ears, and thus reduces the prospect of a reverse block, or so I have read.

Having gotten a reverse block on a dive where I had a mild cold (but could perform the valsalva maneuver with seemingly no problem) and dove down head first, I believe it. (At the time, I was at the Red Sea, which is a long way from California and did not want to miss out on diving.)

I always descend feet first and clear every couple of feet now. I also won't dive with a cold, even I can perform the valsalva maneuver with seemingly no problem.

 

[vcblklion]

Good thread everyone. I have had this issue in the past with AL tanks and had the exact same issue this weekend with a steel tank and was concerned. I switched from AL tank to steel to compensate for positivity at the end of my dive. I used to dive with 26 lbs with AL and now diving with 16 lbs and steel. I am using a Halcyon backplate and 7mm suit/hood and boots. I tried going horizontal to slow myself down but had a really hard time kicking back down. I am considering adding a 6 lb insert to my back plate to compensate.