Bounce diving?

[notscenerob]

I'm using metric, and I'm fairly certain it's entirely feasible, as I see this dive made every day by experienced recreational divers where I live and work. I have made this dive countless times with bottom times of 5-8 minutes, and a slow gradual ascent along the wall, climbed onto the dive boat with 80 bar of air, one hour fifteen minutes later. My personal RMV is near 12 in those conditions... the very short that is obligated upon the beginning of ascent is always clear on my VR3 when surfacing. Divers who are intent on making these types of aggressive recreational dives should acquire the knowledge required, instead of doing it without guidence after being told NO. These are fun dives on a wall, and it's happening daily all over the world.
Now, I hope inexperienced, unprepared divers don't try this, but I've made this dive with numerous course directors, various industry professionals, and customers who have no access to doubles (no technical dive shops in borneo )

Can it be done safely? Absolutely. Should everyone do it? Absolutely not. Was this poster asking for information about diving? Yes... so I gave an honest answer. It's not my place to tell anyone how to dive, unless they are seriously putting themselves or others at risk. In the clear waters of Hawaii, I believe this to be within acceptable limits of risk.


A bounce, as commonly defined by diving professionals... a quick drop and direct ascent, is DANGEROUS in my book. But a "bounce to 55m" as used by live aboard divers, tropical wall divers etc is no problem in my book. Divers who are intent on making these types of aggressive recreational dives should acquire the knowledge required to execute safely, instead of doing it without guidance after being told NO.

 

[TSandM]

notscenerob, your post really brings up a basic underlying idea in diving, which is that each of us simply has to make his own decisions about how much risk he is willing to take in pursuing this sport. I don't have a problem with someone deciding that the dive you describe is OK; I have a problem with someone deciding it's OK without having the information to evaluate the risk properly. I know that I made my 10th dive of my life to 130 feet in Molokini Crater, using an Al80, but at that point, I had no education in gas management and had never heard of the concept of rock bottom or minimum gas. In retrospect, I evaluate the risks of that dive quite differently now than I did then.

One of the unspoken things in my diving is that, when I go underwater with a buddy or buddies, I consider myself to have made a compact with those people, that I will do everything I can to get them back to the surface safely in the event of a problem. If I am at 130 feet on an Al80, I can't do that, so that violates my agreement with them, and I will no longer do those dives. The risk is small (how many dives have we all done without a catastrophic gas failure?) but to me, it is unacceptable.

 

[Rick Murchison]

Plenty of folks have done deep bounces with no ill effects... back in the early 70's, a bounce to 200 FSW on a single 72 was a rite of passage for macho young men; fatalities and bends were rare, but every now and then a young man got hurt, or just didn't come back.
But we were young, diving itself was still young, and we were Ignorant (capital "I").
We know a lot more now...
We know that a single 72 (or 80) isn't enough reserve gas to safely cover a safe ascent for a two diver team should one have a catastrophic gas failure at 200'.
We know that a gas hog can't make the bounce on a single 72 or 80 without either running out of gas or exceeding safe ascent rates.
We know that for some folks, 200' is just too deep on air - they just go stupid and don't swim back up.
We know that even the most experienced divers' faculties are somewhat under a cloud at 200' on air, and that they can't count on themselves to make swift accurate decisions there.
We know that no one knows how deep they can go before becoming debilitated by narcosis until they've been there; put another way, no one knows how shallow they'll go stupid until they've had it happen.
Sooo... I'd be remiss to say "sure, you can do it" to any bounce profile, even if it's the only dive of the day - you may be the 155' vegetable...
Who knows?
Rick

 

[drbill]

I frequently dive deep and have had several refer to my dives as bounce dives. However, my understanding (confirmed by Rick) is that a true bounce dive involves short bottom time and total dive time. Even when I dive very deep (180-200 ft max), my total dive time is rarely less than 45 min and often in the hour range with multiple deep stops and a very extended shallow (10-20 ft) stop. I certainly wouldn't call these bounce dives.

The only true bounce dives I've done intentionally were gear recovery dives for folks on the King Neptune dive boat. I don't like to do those, even if they involve only moderate depth (50-80 ft) and especially if I'm doing a number of dives that day.

Why add any more risk to your diving than is necessary. And why would anyone do a bounce dive unless it was for gear retrieval, freeing an anchor or other necessary purpose. What can you possibly see and enjoy on a "recreational" bounce dive?

Wonder why no one (to my knowledge) has created a bounce dive specialty certification? Hmmm...

 

[Bismark]

I'm using metric, and I'm fairly certain it's entirely feasible, as I see this dive made every day by experienced recreational divers where I live and work. I have made this dive countless times with bottom times of 5-8 minutes, and a slow gradual ascent along the wall, climbed onto the dive boat with 80 bar of air, one hour fifteen minutes later. My personal RMV is near 12 in those conditions... the very short that is obligated upon the beginning of ascent is always clear on my VR3 when surfacing. Divers who are intent on making these types of aggressive recreational dives should acquire the knowledge required, instead of doing it without guidence after being told NO. These are fun dives on a wall, and it's happening daily all over the world.
Now, I hope inexperienced, unprepared divers don't try this, but I've made this dive with numerous course directors, various industry professionals, and customers who have no access to doubles (no technical dive shops in borneo )

Can it be done safely? Absolutely. Should everyone do it? Absolutely not. Was this poster asking for information about diving? Yes... so I gave an honest answer. It's not my place to tell anyone how to dive, unless they are seriously putting themselves or others at risk. In the clear waters of Hawaii, I believe this to be within acceptable limits of risk.


A bounce, as commonly defined by diving professionals... a quick drop and direct ascent, is DANGEROUS in my book. But a "bounce to 55m" as used by live aboard divers, tropical wall divers etc is no problem in my book. Divers who are intent on making these types of aggressive recreational dives should acquire the knowledge required to execute safely, instead of doing it without guidance after being told NO.

I would still like to see your profile. Specifically, how much gas are you using on your descent, how much on the ascent, how much at depth, what is your turn pressure, What do you expect to surface with, etc, also what exactly is the multi level component of your dive you are referring to. Also, you mention your dive is hour and 15 minutes long..... to 55m...on a single AL 80. After 5-8 minutes at 55m, with an RMV of 12, I would really like to see your profile and gas planning please.

Thanks in advance.

 

[ScubaAndDreams]

Which dive operator in Hawaii will let him do this "Bounce Dive"? On Air, with an AL80? I know of...none. Which island are we talking about here?

 

[Rick Murchison]

I would still like to see your profile. Specifically, how much gas are you using on your descent, how much on the ascent, how much at depth, what is your turn pressure, What do you expect to surface with, etc, also what exactly is the multi level component of your dive you are referring to. Also, you mention your dive is hour and 15 minutes long..... to 55m...on a single AL 80. After 5-8 minutes at 55m, with an RMV of 12, I would really like to see your profile and gas planning please.

Thanks in advance.

Well, shoot, anybody can do the math....
Let's see here, using a standard 80 at 204 bar to start the dive...
Descent to 55m @ 18 mpm, 119 l (11 bar)
6 minutes @ 55m, 468 l (44 bar, leave the bottom with 149 bar)
Ascent to surface @ 9 mpm, 238 l (22 bar)
3 minute safety stop @ 4.5 m, 52 l (5 bar)
leaving ~ 122 bar for the remaining 57 minutes of a 75 minute dive... so...
he can complete the dive by tooling around in the shallows at 30' and ending up back on the boat with an empty tank.
Piece of cake.
Rick

 

[lamont]

And there are people who have not. Even one young man in the PNW area who went with his instructor, but didn't come back. In fact, it was some months before they found his body.

There's at least one other body still down there as well.

Of course in the PNW you've got the additional problems of low visibility and cold, but even in hawaii you still have to deal with a large amount of narcosis and getting into a panic cycle or vapor lock at that depth on an Al80 on air will still wind up killing you just as dead as up here.

 

[Bismark]

Well, shoot, anybody can do the math....
Let's see here, using a standard 80 at 204 bar to start the dive...
Descent to 55m @ 18 mpm, 119 l (11 bar)
6 minutes @ 55m, 468 l (44 bar, leave the bottom with 149 bar)
Ascent to surface @ 9 mpm, 238 l (22 bar)
3 minute safety stop @ 4.5 m, 52 l (5 bar)
leaving ~ 122 bar for the remaining 57 minutes of a 75 minute dive... so...
he can complete the dive by tooling around in the shallows at 30' and ending up back on the boat with an empty tank.
Piece of cake.
Rick

Thanks Rick, and I hope the poster to whom I posed the question did the same math, 45 cubic ft at 2 ATA at even .5 SAC gives you about......oh....45 minutes....... those last 12 minutes are going to be a bit rough.......

We haven't even talked about Min gas or rock bottom for the diver and his/her supposed buddy on this dive.......cheesh.............

 

[Rick Murchison]

Thanks Rick, and I hope the poster to whom I posed the question did the same math, 45 cubic ft at 2 ATA at even .5 SAC gives you about......oh....45 minutes....... those last 12 minutes are going to be a bit rough.......

We haven't even talked about Min gas or rock bottom for the diver and his/her supposed buddy on this dive.......cheesh.............

Well, the professed SAC is 12 lpm, which is 0.42 CFM, considerably better than the average recreational diver (better than my own planning figures, too, even for deco ).
At that RMV, however, the stated dive is possible, and I know some folks who could make it and actually have gas left over... but only a handful out of a lot of divers. And as you allude, that doesn't cover any buddy or contingency planning.
IOW, in the context of the OP, the profile isn't realistic, at least to me.
Rick