Warning deep "bounce" dives warning

[MXGratefulDiver]

If you are new or old or not yet certified and drawn to the deep...I understand.

Good or bad I too was drawn to the deep. But there is a way to get there safely and that is through proper training, including gear selection and redundancy and experience. Diving is no different than any other group of people. There are different mind sets within the community and it's up to you who you follow. I hope you will make the safe choice and listen to those who deep dive safely through a proven and accepted means of training. And not follow the yahoos who actions have proven fatal to others.

I am not claiming to be some expert, but i do have little experience at this and there are countless others with way more experience than me who are willing to share our journey and knowledge so that others can get there safely, if that's your desired destination. And if you are one of the ones for whom the deep holds no intrest, that's kewl too. Dive on and be safe.

It's common for newly certified divers to be attracted to the idea of going deep. What they need to understand is that the deeper you go, the more important it becomes to be prepared to deal with problems at depth ... the farther away the surface becomes, the less of an option going to the surface becomes. That is the reason why new divers should not be encouraged to go on deep dives ... and the primary problem I have with AOW being taught directly after OW ... it gives new divers the impression they are somehow "qualified" for deep dives, when they haven't yet developed the skills or mindset to plan and perform a deep dive with an acceptable margin of safety.

Risk is something that a lot of entry-level classes gloss over ... maybe because they don't want to scare people. But I think it's important to emphasize the risks associated with scuba diving ... as well as emphasizing that those risks are magnified by increasing depth. Bounce dives are seen by many as a "shortcut" to setting depth records. The reality is that the price for taking the shortcut is to sacrifice your safety margins. If all goes right, it can be an exhilarating dive. If something goes wrong, it can be a terrifying experience ... if not downright fatal.

New divers really do need to hear that ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Don't plan to go deeper than the number of cubic feet of gas on your back.​

Unfortunately, that first rule is excessively conservative. The second rule could bring you to the surface with 300 psi which some might feel is a bit aggressive.

In this case, Rules are for fools. Learn and apply proper gas planning and neither rule is needed.

Now theres something I do on a regular basis (and safely so).
100 ft on an AL80 is no problem whatsoever, Ill run out of NDL before Im running low on gas at 100 ft with an AL80..

That being said, I KNOW what my gas consumption is, Im not just making a random guess that Ill be fine doing it!

Remember what forum we're in ... this rule is NOT for fools, it's for newly certified divers ... which neither of you guys are.

Perhaps you have forgotten what it was like to be new ... when your air consumption was multiple times what it is today ... when your ability to task-load was practically nil ... when it was all you could manage just to keep from corking to the surface while doing a safety stop, particularly if you had to do something as simple as look at your gauge while trying to maintain your position.

Rules of thumb are designed to keep newly certified divers out of trouble. Of course they don't apply to someone with hundreds of dives ... by then you don't need them anymore. But you should never forget why they existed in the first place. When you're a new diver, "overly conservative" is not a bad thing ... I highly encourage it, in fact.

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Sure there may be more considerations the deeper you go and I too have little interest below 130 ft. Unless you are just uninterested in even considering deeper dives and also just want to keep other from considering them also; then work out the parameters and determine the specifics as to why you don't want to do them (and why you feel others also should not).

In my case, I understand it is narcosis considerations that keep me from looking at depths greater than 150 ft. I can figure out how much gas I would want and any deco considerations and they are not my limiting parameters. But I also understand that if I ever put my sights on 200 ft, it is not something I need to mindlessly dismiss.

130 feet may be the recreational depth limit, but new divers shouldn't even be contemplating going there without some additional training and experience ... and even then only with a more experienced diver.

Talking to people about things like narcosis and how quickly you will use up your air at deeper depths is one thing ... experiencing it and understanding it are something else entirely, and are something that new divers should be made aware of and encouraged to address through additional training and experience once they've got their basic OW skills down solid ... but not before then.

... Bob (Grateful Diver)

 

[MXGratefulDiver]

How stressed you as the buddy or you as the one in distress would be is highly individual though..

Ive had people breathe off my octopus for 4-5 minutes because of a blown o-ring on my buddys first stage at a depth of 20m/65ft.
We jumped in and descended immediately to 20 meters. In the grand total of 9 minutes with 2 people breathing off my tank for half of it, we came out with a total consumption from my tank of 0,6 cf/min...
That said, if youre diving with someone who you dont know how responds incidents you shouldnt count on a combined consumption thts low..

I have measured inexperienced divers with a "stressed" consumption rate as high as 2.8 cf/min. Imagine sharing air on a 100-foot ascent with that guy ... :shocked2:

... Bob (Grateful Diver)

 

[MXGratefulDiver]

To introduce "gas management" in OW training is too early.
But make it one of the CORE topic in AOW or at least as 'speciality" for student to choose.

I disagree, since I think having enough air to breathe for any given dive (or, conversely, not having to turn a dive too soon because one really has no idea how to "time it" to get back to the boat with 500psi and so is being overly conservative) is key.

Basic gas management seems like it should be one of the building blocks of OW, to me. What makes you say that's too early?

As far as AOW... well I suppose if it were made one of the mandatory specialties? But still, it seems more basic than that to me since you need air on all your OW dives too.

I doubt there's anyone on ScubaBoard who's more vocal about the need for gas management training than I have been ... but I also believe that OW is too early to teach it ... at least in the format that most OW classes are currently being taught. The OW student has a hard enough time just getting through the basics of equipment and buoyancy control. Gas management concepts can be introduced, but at the OW level that sort of information is unlikely to be retained because of all the other topics that the student is going to be struggling with. What I prefer to do instead is to make the student understand the reasons behind the depth limitations, explain to them that at this point their gas consumption rate is higher than it will ever be again, and give them some rules of thumb for keeping themselves out of trouble. The student who wants to learn more can look it up on my website, and I'm always happy to discuss that topic outside of class, or via email.

At the AOW level, we spend considerable time covering it, both in academic terms and practical application through consumption measurements and dive planning exercises ... they are required to tell me prior to our deep dive how much air they will need for that dive, and why.

It is at this point that divers are beginning to train for deeper dives ... and that makes it the logical point to have them work out for themselves why doing such dives on smaller tanks isn't a good idea ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Seriously, many years ago DIT(commercial dive school) had three divers go do a bounce dive, right after there scuba, its a fast pace scuba. I saw the video of the robot that found one of them, A sixgill was nibbling at his knee and leg. A california fisherman came up and started reeling in sixgills at Alki fishing pier, cause of it. very soon after, like a week sixgill fishing was closed, and still is.

That video told me two things, if you do not know what your in for when diving beyond what you do not know, the sea will eat you. The other is I would not mind dying deep into the sea, I eat seafood, at the end the sea can eat me.

In 2003 two young men from DIT went doing a deep bounce dive off of Lobster Shop Wall in Tacoma, right after their scuba training. One of them came up ... the other one is still down there.

The sea ate him ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Gas planning for beginning divers can be really simple. Discuss the idea of maintaining a safety reserve. Give them a "cheat sheet" for the values for commonly used tanks in the area, for a 60 foot depth (since they're supposed to stay there) and maybe point out how much more it is for deeper dives. Discuss the concepts of all available, halves and thirds, and point out that new divers shouldn't be in any position where thirds are necessary. That's it! And we've had a lot of OW students ask the questions that lead to this information, and nobody seems overwhelmed to get it.

Actually calculating SAC rate and predicting possible bottom time and stuff like that can wait. OW divers do, I think, benefit from the idea that gas planning is possible, and some simple ideas on how to do it.

Yup ... exactly. The key concept to take away at the OW level is simply this ... before you do the dive, you should have a pretty good idea that you have enough gas to do the dive. By limiting your depth and bottom time, you can get there with some of the simple rules of thumb that have already been discussed in this thread. There's no such thing as "too conservative" for a new diver. If you find yourself back at 20 feet with extra gas in your tank, then enjoy some additional time at 20 feet! There's often lots to see at that depth, and if you're bored, well ... you're a new diver ... now's a great time to turn to your dive buddy and practice some of your basic skills.

... Bob (Grateful Diver)

 

[bleeb]

I have measured inexperienced divers with a "stressed" consumption rate as high as 2.8 cf/min. Imagine sharing air on a 100-foot ascent with that guy ... :shocked2:

Along similar lines, I once looked up theoretical numbers just to get an idea of how much people might possibly be able to breathe, by digging up athletic performance numbers for surface activities. Elite large lung people (long distance cyclists, cross country skiers and long distance runners) routinely turn over 75-100 L per min/2.7-3.6 cfm doing their normal activity, and 50 L per min/1.8 cfm is apparently quite common even for people who engage in those activities recreationally. However, endurance activities are typically carried out at output levels that can be sustained for hours, nowhere near near 100% of their short-term cardio capacity.

For maximum emergency levels, consider that lung tidal volumes of 2-3 L/0.070-0.105 cf are supposedly fairly normal for people participating in endurance athletics at recreational, non-elite levels. IIRC, they can easily manage 60 breaths per minute for quite a few minutes (20-40 bpm is more common for lasting the hours they'd normally be doing their thing) so it wouldn't seem out of line that one would have the energy to sustain near maximum volume for quite a few minutes in an emergency. This gives a theoretical figure for people in decent recreational cardio condition of around 120-180 L per min/4.2-6.4 cfm, or likely higher if you are a varsity track athlete or a young male Boston Marathoner.

Now keep in mind that for the moment, all this involves a lot of theoretical hand waving. However, it seems to suggest that if the excrement really hits the rotary air impeller, the extremes for the 'really bad' case for gas consumption might be considerable. Also, consider that while people that regularly participate in endurance athletics for recreational purposes aren't by any means a majority of the population, they aren't that uncommon. For instance, I imagine most active-duty military types are probably capable of this, if they aren't regularly doing it already.

 

[VooDooGasMan]

One of the reasons Why divers in the 50's and 60's were very good divers and still are today for as old as they are, is they learned everything in one book, not broken down in sections.

The books taught everything, aqua lung and single hose, Even taught in water recompression, and gave tables for it, you must have the proper gear to do so. When you were done with book you had the knowledge to be a safe diver.

The thing that changed was, when someone wanted certified they did not have the time to take a long class and the money it cost.

Today is fast pace class to get you in the water, buy gear and take another class. This is a problem with all people, they will not take the next class, so now they have very little knowledge of how to dive safely.

SB is a very good program for diving cause of the way the dive Industry is structured these days. New divers can learn and see why a certain class will get them the experience in the field they want to adventure. New Divers can see the discussions of so many different divers in so many different areas.

The best thing for a new diver to do is be able to learn all they can and be aware of what can and cannot happen.

 

[Blue Sparkle]

I doubt there's anyone on ScubaBoard who's more vocal about the need for gas management training than I have been ... but I also believe that OW is too early to teach it ... at least in the format that most OW classes are currently being taught. The OW student has a hard enough time just getting through the basics of equipment and buoyancy control. Gas management concepts can be introduced, but at the OW level that sort of information is unlikely to be retained...

Good points and I see what you are saying. As I think back though, the fact that gas-management existed was not really brought up in either of my OW classes, and that bothers me. So maybe what I should have said is what came up in later posts by you and others: That OW is not the time for complicated gas planning, but that it would be a good time to explain that the concept exists, to mention when would be the right time to go into it further (AOW, for example, or one one's own when desired), and to cover some basics that can be used right away.

I agree that a bit of extra time back near the boat is a good/fun time to practice things. OTOH, I felt like I was improving as a diver when I figured out my gas use enough to finally get TO the reef instead of worrying that I should turn around sooner to arrive at the ladder at the magical 500 psi and actually getting back (under) the boat with like 2000 psi (Not that there's anything wrong with that, but it might have been nice to have basic tools for judging what I was doing sooner.)

Blue Sparkle