Learned Wrong...

[Deep South Divers]

I would place the emphasis on “SHOULD never need to ditch weight at depth”. I guess we agree that dumping weight is for emergencies that SHOULD never happen, but we all know can and do, albeit rarely.

Why?

Let's say that a diver experiences a total out of gas situation with no buddy present... When this happens, is he/she not already neutral? If not (let's say that he/she was laying on the bottom), does it not make sense that the diver should simply swim up and do an emergency swimming ascent? Does it not make more sense to solve the problem by being properly weighted to begin with, rather than attempt to fix the overweighting issue by ditching at depth - with a possible uncontrolled ascent as the likely result - during the gas emergency?

Here is where there is some distance between us. I have regularly practiced free ascents since my first Scuba class in the early 1960 as do many people trained in that era or in the Navy.

I assume that by "free ascent" (a "free ascent" simply means that you're not on a downline or anchor line), you mean "emergency swimming ascent" or "controlled emergency swimming ascent" - that is, you swim to the surface as if you're out of breathing gas without any redundant supply. The idea of this, of course, is to train a diver to face a possible DCS hit in lieu of drowning. No doubt - I would choose that over drowning, too!

I, too, have been trained in controlled emergency swimming ascents, and while I very rarely practice them (physiologically, it's unhealthy), I agree with you that they do amazing things for the psychology of the diver and his/her confidence level.

...But a CESA is not an "uncontrolled bouyant ascent." My argument is that, given the situation that you're using, a diver SHOULD perform a CESA. At no point should a diver practice an uncontrolled bouyant ascent by ditching weights at depth.

More specifically for others reading this, the accepted standard for freedivers is neutral at 20 Meters/66' or the target depth, whichever is shallower. The objective is to be positively buoyant through most of the water column as a partial safety measure against SWB (Shallow Water Blackout) and to minimize the workload (save O2) at the most critical part of the ascent.

Right. So if the freediver is positively bouyant by design to address the possibility of shallow water blackout, then why would he also consider ditching his weight at depth?

Not sure I understand. There are no ill-effects to a freediver that makes a very buoyant ascent from depth. Look at the competitive standards for the No-Limits class for Apnea divers. I think that most freedivers disagree with this assessment and view dropping their weight belt as the recommended procedure whenever there is concern of a blackout of serious disability.

In the No-Limits class, support divers are available for Apnea divers. There is also a weighted sled that takes them to depth, and once the depth is achieved, the diver opens a valve which inflates a lift bag that takes him to the surface. By comparison, ditching weights - and many No-Limits, Apnea divers don't wear weights at all when they ride the sled - would have little effect. The argument about "ditching weights" for a No-Limits diver is completely moot, and not at all what scuba divers are talking about when they mention "ditching weights at depth" anyway. At best, the subject is simply a tangent of interest, and not pertinent.

Regardless of the source, you don’t need to dump weight when you have breathable gas. Nobody is discussing that. When visibility is bad, your buddy can’t be found quickly enough, and/or it all hits the fan; do you recommend passing out and sinking to the bottom until rescued?

Of course not. I recommend swimming up. I recommend a CESA, in accordance with both your and my training. I recommend maintaining control and ascending immediately. As an OOA diver ascends, he'll get another breath as ambient pressure decreases, although I'm not sure that in a CESA the diver would notice.

During a CESA, a diver - who was either neutral or nearly neutral when the OOA occurred - will experience the expansion of the bubble in his/her BC anyway... That is, the CESA diver becomes more and more positively bouyant as he gets closer to the surface anyway... No ditching required.

In fact, I believe that it can be argued successfully that an OOA diver would not want to take the few precious seconds to ditch weight. Not only is it pointless (because the diver will get progressively more bouyant anyway), but time consuming, where mere seconds count.

Other than developing the initial skill and maintaining it as a reflex, I think we are largely in agreement when it is appropriate use to dump weight.

Well, I'd love to agree with this point, but as much as I hate to use the word "never," I would actually consider it when talking about ditching weight at depth. Do you still feel that we are largely in agreement?

Unfortunately the options for divers who don’t are to panic and die, pass out trying to decide what to do, or kill themselves trying to make a free ascent they lack the skill and emotional preparation for.

Well... If they're taught to swim up, they'll get another breath every 33' or so, even if the tank is dead empty... While becoming progressively more positively bouyant as they ascend. Why teach them to ditch their weight at depth and attempt to solve a weighting issue right in the middle of an OOA? This seems dangerous, time consuming, and distracting from the real problem - their next breath.

Unfortunately, most divers have not invested enough thought or training to make this possible. Panic causes far too many people to get stupid and kill themselves. You might find this post interesting if not the entire thread: Panic in the experienced diver?

Thanks... Checking it out...

 

[Thalassamania]

The question was, 'This made me curious about what divers were taught that was wrong as opposed to incomplete, overly simplified, a different technique, or less efficient."

Many of the things listed where quite correct at the time they were taught, and are still correct today if one is using the same gear or techniques that were used then.

I was taught by an instructor to turn my tank all the way on and then back a 1/4 turn. I know of two people (personally) now who have found it very hard to breath at depth by doing this.

Then I suspect that they turned the valve, new or old, a good deal more than 1/4 turn.

How about this one, still in all the books,

Do not look at the fase of your SPG, it might blow in your face.

As a matter of fact, 99% of all SPGs have a (hard)plastic rekieve valve in the back, that will blow out in case of a failiure.
That will hurt you,not the glass/plastic face.

This used to happen, but the caution was not to look in the face of the SPG, WHEN TURNING IT ON!

... I learned that a snorkel was an important piece of safety equipment ...

... Bob (Grateful Diver)

It is if you need me to rescue you.

There are still old-school instructors out there that teach to deflate the BC before ascending.

This made sense when diving weighted to be neutral at your dive depth.

...

Helium is a bad gas to deco off of.

Most of the problems with my education were errors of omission, or bad technique on my part that my instructors failed to correct.

I'd say that there is some truth to both of those. Helium bends were bad news and in the early days included patches of skin sloughing off. Helium bends were rather hard to treat back then too.

If you put your mask on your forehead after diving a DM will come frantically to your rescue.

This stems from the California coast, back in the day, when most all diving was beach diving.

This technique had merit in the days when wetsuits didn’t compress much and people adjusted their weight to be neutral at 10' with 200 PSI on their tank. Your negative buoyancy wasn’t much to swim against and it avoided having to deal with it on ascent. The ascent rate was also 60'/minute so it was easier a lot of times. It’s not such a good idea if you are leaving the bottom 10 Lbs negative though.

Actually we adjusted our weight to be neutral at the dive depth. There's a graph of this in the Univ. of Michigan Reseach Divers Manual of the early 1970s.

I have heard that… where the heck did that come from? I don’t do that much anymore anyway because of bi-focal lenses. I told a DM once not to even try it unless he saw the mask on my forehead, I disappear from sight, and he sees bubbles… even then; cancel it if the water turns red.

Somewhat related: http://www.scubaboard.com/forums/ad...ons/398734-preventing-mask-loss-vs-spare.html

See above.

I was taught that the frog kick is "not commonly used in scuba diving, but can provide a restful variation for long surface swims"
(Jeppeson's Open Water Sport Diver manual, page 18) ...

... Bob (Grateful Diver)

Frog kick was not a standard kick on the California coast, the large partical sediment that was found in most places meant that flutter kicks were not a problem.

The instructor did I'm sure but having a valve not completely open or closed means it can be a little open and/or a lot closed.

Someone accidentally closing an open valve and backing it off a 1/4 turn will be able to breath and inflate their BC on the surface during a pre dive check but find it very hard to breath at depth. unless they are also taught to look at the SPG to note a dip in the pressure (I wasn't) they will not catch this error themselves.
I have never personally seen a jammed valve but then I don't crank on them either. Even if it did jam I would prefer to resolve a non emergency on the surface than an air failure at 60'.
The experience for doubles may be different as you manipulate the valve at depth but I was taught this during OW and doubles were not mentioned. I also have a very large aversion to anyone touching my valve once the tank is on my back as I instinctively feel I need to recheck their check (if you know what I mean). In my early days I actually turned someone else's air off that way (left post, doubles).

1/4 turn off will never cause this problem, even with new valves though I've not tested this with the most modern single turn or are they turn and a half valves.

All through my dive certification classes I learned to only dump air via the inflator hose because "these rental BC's don't have hip dumps." As you can imagine, I found out later that they did, and now (with my own BC) that's what I usually use. But it took a while to get out of the inflator habit.

Most rental BCs, in the past at least, were the cheapest possible models in most cases and lacked a rear dump.

 

[MauiScubaSteve]

There are still old-school instructors out there that teach to deflate the BC before ascending.

I tell my students that if they can easily swim up with no air in the BC, they will not have a runaway ascent from expanding air not venting quick enough from the BC. I also tell them they should be in control, make their safety stop between 12-18 feet deep, and that exertion should be minimized while diving, especially at safety stops.

For many divers, ascending with no air in the BC is just fine.

 

[miketsp]

I tell my students that if they can easily swim up with no air in the BC, they will not have a runaway ascent from expanding air not venting quick enough from the BC. I also tell them they should be in control, make their safety stop between 12-18 feet deep, and that exertion should be minimized while diving, especially at safety stops.

For many divers, ascending with no air in the BC is just fine.

When I first learned to dive, my Spirotechnique wet suit was almost incompressible and you were only slightly negative at depth so ascending without any additional buoyancy wasn't an issue.
When I re-qualified 20 years later it was in tropical water diving in a T-shirt so when the instructor taught me to dump my (new-fangled) BC before ascending I didn't give it much thought and it wasn't an issue.
But when I then started diving cold water in a semi-dry with a lot of thick compressible neoprene, I immediately realized that this was no longer safe practice.
And in fact there are various studies out on the Internet that found that if a diver has to kick up with excessive force it is all too easy to concentrate on the kicking and forget to keep the airway open.
Over the last few years I've witnessed quite a few OW courses from various systems and they all taught neutral ascents.

So I don't know what the water temps are where you are teaching. If they're warm then what you're teaching may not be a problem, but you're not teaching a safe technique if your divers then move elsewhere.

 

[Blue Sparkle]

All through my dive certification classes I learned to only dump air via the inflator hose because "these rental BC's don't have hip dumps." As you can imagine, I found out later that they did, and now (with my own BC) that's what I usually use. But it took a while to get out of the inflator habit.

Most rental BCs, in the past at least, were the cheapest possible models in most cases and lacked a rear dump.

I see what you are getting at, in terms of some modern "wrong teaching" actually being things that legitimate artifacts from diving history. However in my case I was diving a (rented) brand-new, top-of-the-line BC, and my instructor was barely 30 years old, so I really think it was just a case of him thinking/assuming there was no rear dump.

I was a green, bumbling OW student, and he was the expert, so I took his word for it and followed his suggestion of only using "lifting the inflator hose" to dump. As it turned out, there was a rear dump (I found it on the last day when I disassembled the BC for an extra-thorough final rinsing).

Now I have my own BC (yay!) and I have acclimated to (and prefer) the rear dump most of the time.

Blue Sparkle

 

[Akimbo]

…

I have heard that… where the heck did that come from?…

See above…

I was wondering where "a mask on your forehead meant you needed help" came from. Does losing your mask entirely mean "Call for a Coast Guard chopper”? I can think of less subtle and mistakable indicators. Is/was this just a California thing? I suspect it was everywhere after Sea Hunt aired.

I wonder if the larger oval masks that dominated in that period stayed on the forehead better than today's low volume masks. Several guys I dove with used Cressi Pinocchios but I can’t recall if they put it on their forehead as often or not. I could never get a seal on them due to my gorilla brow.

 

[Akimbo]

…Now I have my own BC (yay!) and I have acclimated to (and prefer) the rear dump most of the time…

I’m confused. Are you describing what I know as a pull dump like this?


Or an overpressure valve with a manual dump (string) I know as a rear dump like this?


Images are from: EXP Wings by Dive Rite - Dive Gear Express, where there is more description.

 

[oreocookie]

Akimbo, I know you're asking Blue Sparkle, but I think my OW experience was similar. The rental BC's that I learned in had a pull dump and an OPV with manual dump at the hip. Neither were even mentioned; if you needed to dump air, you lifted the inflator above your head. When I bought my own bc this summer, I was very familiar with the fact that there were hip dumps when I started using it, and they're the main way I dump air now, but I'm also now in a position to be able to use them, where I wasn't able to use a hip dump before as there's not very useful if your hip is at the lowest point of the bc.

 

[Akimbo]

Sorry, I missed this earlier:

… I assume that by "free ascent" (a "free ascent" simply means that you're not on a downline or anchor line), you mean "emergency swimming ascent" or "controlled emergency swimming ascent" - that is, you swim to the surface as if you're out of breathing gas without any redundant supply. The idea of this, of course, is to train a diver to face a possible DCS hit in lieu of drowning. No doubt - I would choose that over drowning, too!...

We must be using different references: U.S. Navy Diving Manual, Revision 6, 15 April 2008, Page 7-38:

7-8.1 Emergency Free-Ascent Procedures. If a diver is suddenly without air or if the SCUBA is entangled and the dive partner cannot be reached quickly, a free ascent must be made. Guidelines for a free ascent are:

1. Drop any tools or objects being carried by hand.
2. Abandon the weight belt.
3. If the SCUBA has become entangled and must be abandoned, actuate the quick-release buckles on the waist, chest, shoulder, and crotch straps. Slip an arm out of one shoulder strap and roll the SCUBA off the other arm. An alternate method is to flip the SCUBA over the head and pull out from underneath. Ensure that the hoses do not wrap around or otherwise constrict the neck. The neck straps packed with some single-hose units can complicate the overhead procedure and should be disconnected from the unit and not used.
   4. If the reason for the emergency ascent is a loss of air, drop all tools and the weight belt and actuate the life preserver to surface immediately. Do not drop the SCUBA unless it is absolutely necessary.
4. If a diver is incapacitated or unconscious and the dive partner anticipates difficulty in trying to swim the injured diver to the surface, the partner should activate the life preserver or inflate the buoyancy compensator. The weight belt may have to be released also. However, the partner should not lose direct contact with the diver.
5. Exhale continuously during ascent to let the expanding air in the lungs escape freely.

It is derived from the earlier use of the term in submarine escape. Those ascents were generally buoyant, though not necessarily, and ideally very rapid — 300-600’/Min. Google “stanky hood” if interested. Also see: http://www.scubaboard.com/forums/basic-scuba-discussions/384619-cesa-40ft.html and http://www.scubaboard.com/forums/ad...ns/384868-lack-oxygen-during-free-ascent.html for the long version of the discussion.

Sidebar: Captain George Bond, the father of saturation diving, made a record free ascent from the submarine USS Archerfish from a depth of 363' in 1959. It hardly seems like a big deal today where freedivers make the round-trip on one breath deeper than that. But it was a huge accomplishment at that point in the understanding of the diver physiology.

​

The part I find interesting is most “modern” Scuba instructors believe it is impossible for some reason.

 

[Thalassamania]

Papa T often did that which is impossible today ... he just forgot to ask.


Dr. George Bond and Chief Engineman Cyril Tuckfield following record buoyant ascent in 1959, indicating that they are in trouble and in need of rescue.