50-60m recreational depth?

[DennisS]

When I was in Coz about 10 years ago I met two yahoos, one an ex junkie (who claimed scuba was his new high) that did 200 ft bounce dives on single AL 80s. They said it was so they could earn the "At 200 ft no one can hear you scream" T shirt. I called BS and they showed me the profiles, they matched up real close, pretty much a sharp V with a plateu at 15. Someone that should have known better took them out and did the dive.

 

[Cave Diver]

When I was in Coz about 10 years ago I met two yahoos, one an ex junkie (who claimed scuba was his new high) that did 200 ft dives on AL 80s. They said it was so they could earn the "at 200 ft no one can hear you scream" T shirt. I called BS and they showed me the profiles. Someone that should have known better took them out and did the dive.

I don't remember meeting you.

 

[DennisS]

I don't remember meeting you.

I heard you framed the shirt?

 

[redacted]

If the profile is as described, then I , too, assume it was something like this. Few minutes "deep" and the rest spent working quite shallow. Not something I'd do (on a single Al80), but it's doable IF nothing goes wrong.

An Al80 should be plenty of gas for a bounce dive to 200 ft if your SAC is good. I figure with a SAC of .5 it should take no more than 1/3rd of your gas (actually estimated 20 cu ft). If there is a gas problem, that should leave enough gas in a buddy's tank to make the surface with no time to waste. Yes, that is doing closer to 60 ft per minute rather than the now acceptable 30.

I would be more concerned with narcosis. If narcosis is the problem that develops, clear thinking may be gone along with any useful gas plan.

I took a shot at Marichibo Deep in Cozumel one time. It is a wall (shear rock cliff) that starts at 120 ft and just keeps going straight down out of sight. The plan was to drop over the edge down to 150 ft, stay a few minutes, and then work our way back up and over to Maichibo Shallow (30 ft humps on a 90 ft bottom) and continue the dive at about 60 ft. One diver stopped at 120. One diver dropped to 150. My wife and I stopped at 140 when my face went numb just like at the dentist in the early '50s. All divers were good on gas and we ended up with almost an hour of total dive time including close to 30 minutes in the 30 to 60 ft range.

It was interesting but I'm in no hurry to do it again.

 

[Rhone Man]

I'll ask. What is 'Snoopy'?

 

[MXGratefulDiver]

My friend insists that on a vacation, an instructor took him down to 50m. He was using an al80. He says the dive was 25 minutes long. The dive tables only go to 39m. What is the deal? Thanks.

Last guy I knew who followed an instructor on a dive like that ended up with a bottom time of about 10 months. There's a thread in the Accidents forum about it, in fact ...

... Bob (Grateful Diver)

 

[Doc Harry]

I know of a resort that takes experienced guests on a 185-foot bounce dive to a ledge on a 3,000-foot wall. They use air-filled single AL80s and a bottom time of 5 minutes (5 minutes includes descent time and time on the ledge at 185 feet). At the 5-minute mark everyone starts their ascent.

I wanted to do that dive when I was a novice, but they wouldn't let me.

Now I wouldn't want to do a dive like that unless I was on Trimix with double cylinders. I did a 150-deco dive on Nitrox in the cave Eagle's Nest (twin 95s with EAN24 and a 40 with 50%), but the narcosis and impairment was too much for my taste.

 

[hg frogman]

To the OP :
Most probably (if no brag from your friend) that was a very short bounce at 50 meters/165 feet, making for a few minutes of deco stops. Dive computers, and dive tables for deco diving, allow air dives deeper than 39 meters/130 feet (unlike PADI tables). Thanks to his/her dive computer, and while having (hopefully) your friend staying close and at the same depth than him/her at any moment, the instructor took care (hopefully) of the air consumption, dive profile and deco stops for both divers. Unless your friend had his/her own dive computer ; you didn't tell much.

For me, judging what they did as really hazardous, or not, depends on the sea conditions that prevailed (for instance, narcosis hits more quickly in cold, murky water than in warm, clear water) ; on the certification, experience (you gave no clue about them), aquatic gifts, SAC (a short bounce to 50 meters with an AL80 is doable with a low SAC), fitness and self-control, of your friend and of the instructor ; and on local laws, that have to be respected. But personally I would never allow such a dive to divers not specifically trained and certified for this depth, unless it's part of their regular training with a recognized agency.

To others :
In my country, bounce air dives in open water down to 50-60 meters/165-200 feet on a single tank (usually a 15 liters/120 cubic feet, with no bailout and no stage) are allowed by law/diving federation rules and are routinely done (by adequately trained and certified leisure divers, ie CMAS ***, not by beginners !) ; while such dives are frowned upon, or even judged suicidal, in some other countries. The same can be said of the possibility of freely buying and owning firearms (forbidden in my country). Cultures, laws, practices, and definitions of what is overly dangerous and what is not, are not the same everywhere ; and they change in time.

With all due respect, Scubaboard often sounds very North-American. But even in North America, I guess that in the old days (till the end of the seventies) many experienced divers were using Navy tables and doing single-tank deco air dives down to 200 feet ; then came the agencies calling themselves "recreational" and making almost everyone believe, thanks to intensive advertising, that so-called "recreational" no-deco diving, down to 130 feet maximum, was the only way ; and then came the "tech" agencies.

 

[catone]

I'll ask. What is 'Snoopy'?

This:
It Happened in the Florida Keys - Google Books

 

[Tortuga68]

This:
It Happened in the Florida Keys - Google Books

Huh??