50-60m recreational depth?

[Ericlt1]

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.

[Cave Diver]

50 meters is ~164'. Outside the recreational limit of any agency I know of. A bit ill-advised as well.

25 minute total dive time maybe. 25 minute bottom time at depth on an AL80, doubtful.

The instructor may have taken him to that depth, but I wouldn't call it "recreational." Maybe he was doing an advanced class? Deco procedures?

[Captain12Pk]

50m works out to about 164fsw. Definately well beyond what would be considered recreational. I would consider attempting a dive to this depth on a single al 80 reckless and irresponsible. An Instructor taking someone (presumably not T certified) to this depth, I would consider negligent. But that's just my opinion. I've heard of dumber things, but not by much.

[Thalassamania]

Then your friend is either embellishing the truth, or had a dangerous fool for a buddy.

[Captain12Pk]

With an assumed breathing rate of .5 cfm, he would have consumed about 74.50 cf of gas just during the bottom time. Not to mention the descent time, ascent time and the necessary deco time. Highly unlikely.

[Rainer]

Sounds like a profile we do often. 25 minutes at 160' on an Al80.



[Now, we usually switch back to the doubles for the ascent, before settling in for 30 minutes of deco on another bottle...]

[Superlyte27]

lol...

[tkdgodess]

He probably just followed the leader (by him saying the instructor TOOK him to 50m - any thinking diver would be able to read thier own gauges...otherwise he would have said "I" dove to 50m) and didn't understand that he was diving to 50'. Sometimes accents, the instructor switching between feet/M in his lingo depending on the crowd he's leading and your friend got confused.

[Captain12Pk]

Sounds like a profile we do often. 25 minutes at 160' on an Al80.



[Now, we usually switch back to the doubles for the ascent, before settling in for 30 minutes of deco on another bottle...]

Now looking at it that way... yeah, that makes sense.

[marinediva]

Think your friend is pulling your leg.
I would lay money on 50 ft not M.
Often hear mistakes made by people who talk in imperial talking with others who work in metric.

[spectrum]

Probably 50 feet and he just got confused on the units. As others have outlined dive to 50m is not trivial outing.

[Crush]

Like Spectrum said - he likely got the units mixed up. Here is a test - ask him about what he saw at the bottom. If he is able to recall it with perfect clarity and he is a new diver who was on air, he was not at 50 meters. If instead he barely recalls any of it, he may have hit 50 m.

[Superlyte27]

He could have went to 160' and hung out for 3 or 4 minutes, moved up to 80' and hung out for 10 minutes, moved up to 30 feet and hung out for another 10 minutes and never entered deco.

[Superlyte27]

I know instructors who shouldn't be doing penetration dives themselves taking brand new students to see Snoopy on the Spiegal Grove in Open Water gear. Anything is possible with instructors these days.

[Rainer]

He could have went to 160' and hung out for 3 or 4 minutes, moved up to 80' and hung out for 10 minutes, moved up to 30 feet and hung out for another 10 minutes and never entered deco.

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.

[Cave Diver]

I know instructors who shouldn't be doing penetration dives themselves taking brand new students to see Snoopy on the Spiegal Grove in Open Water gear. Anything is possible with instructors these days.

Have you ever discussed it with them?

[Mr Carcharodon]

Some of the more aggresive dives in Mexico and Truk have similar profiles. You can dive down to 50 meters on a 80 no problem. Of course if anything goes wrong getting back to the surface maybe a bit of a trick. The liability environment influences what’s possible. Those dives are not recommended for a host of reasons.

[Superlyte27]

Have you ever discussed it with them?

Yah,
You know instructors. They know everything, can't be taught anything. I hope he chimes in. He's on this board. :)

[Cave Diver]

Yah,
You know instructors. They know everything, can't be taught anything.

That phenomenon extends to many other groups as well.


I hope he chimes in. He's on this board. :)
I do as well, I'd be interested in hearing the thoughts on it. Perhaps we should start a separate discussion for the topic?

Edit - New thread located here: http://www.scubaboard.com/forums/advanced-scuba-discussions/356186-instructors-doing-trust-me-dives.html

[Superlyte27]

We'll title it "Visiting Snoopy on an Aluminum 80" ???

[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?:D

[awap]

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'?

[NWGratefulDiver]

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 (http://books.google.com/books?id=xf5ALD0h-08C&pg=PA105&lpg=PA105&dq=snoopy+spiegel+beagle&source=bl&ots=PHUmih-WZ1&sig=YBD5_cJ9CLclUhQTDADIhTvb2zI&hl=en&ei=uKK5TJLkFYbGlQepvaiUDQ&sa=X&oi=book_result&ct=result&resnum=4&sqi=2&ved=0CCEQ6AEwAw#v=onepage&q=snoopy%20spiegel%20beagle&f=false)

[Tortuga68]

This:
It Happened in the Florida Keys - Google Books (http://books.google.com/books?id=xf5ALD0h-08C&pg=PA105&lpg=PA105&dq=snoopy+spiegel+beagle&source=bl&ots=PHUmih-WZ1&sig=YBD5_cJ9CLclUhQTDADIhTvb2zI&hl=en&ei=uKK5TJLkFYbGlQepvaiUDQ&sa=X&oi=book_result&ct=result&resnum=4&sqi=2&ved=0CCEQ6AEwAw#v=onepage&q=snoopy%20spiegel%20beagle&f=false)

Huh??

[Druid]

50 meters is ~164'. Outside the recreational limit of any agency I know of.



SAA (http://www.saa.org.uk/) Dive Leaders are qualified to 50m, as are CMAS*** divers.

I have seen people diving the Blue Hole in Dahab using AL80s, the top of the arch is ~56m. They don't spend 25mins at that depth though ;)

[Cave Diver]

I'll ask. What is 'Snoopy'?

Scroll down to about mid page: Spiegel Grove | USS Spiegel Grove (http://www.fantasticendeavors.com/travel/spiegel_grove.html)

And see this video ~58 seconds in: 09102006 Spiegel Grove - Snoopy (http://video.google.com/videoplay?docid=672835529341621213#)

[catone]

Huh??


See posts #14 and #20. Did you click on the link?

[Tortuga68]

Did you click on the link?

Yep. Nothing about snoopy there

Found him in CD's link though

[LeadTurn_SD]

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.

There were t-shirts????? Not just the baseball cap???? :D

200' or a bit deeper on single Al80's or steel 72's done as bounce dives were common in the "bad old days" among the "yahoos" here as well.

I think it was a right of passage in some regions among spearos, sport divers, the "Young and the Restless", etc.

VERY foolish, but it happened.

Best wishes.

[Cave Diver]

There were t-shirts????? Not just the baseball cap???? :D

Nuff said.......

Best wishes.

I'll take one out of the frame and post pictures later. ;)

[asj]

If he is able to recall it with perfect clarity and he is a new diver who was on air, he was not at 50 meters. If instead he barely recalls any of it, he may have hit 50 m.

You ever been to 50m on air? I've done it in a hyperbaric chamber, and I remember the time at 50m well enough to give a clear account. Yes I was narced, but for my buddy and myself it was kind of a let down, there was must less of an effect than I expected. Of course with helium high voices...it's good for a laugh.

Of course for the girl who decided it was now a good time to do a headstand and see if she could spin on her head....then decided it might be a good time to start swimming....might not be your best buddy on your next dive to 50m. :D

If you ever get a chance to take a "dry dive" in a chamber it's worth it. Let me warn you, it gets damn hot in there, well over 40c by the time you hit 50m.

[Tortuga68]

Doing a chamber ride to 50m doesn't necessarily produce the same narcotic effect as diving to 50m

[Mikemccrsa]

Doing a chamber ride to 50m doesn't necessarily produce the same narcotic effect as diving to 50m

Any idea why this would be :confused:

The way I see it - the air content/ratios is the same and the pressure is the same so it should produce the same level of narcosis. I don't have much experience with deep diving but I believe that the effects of narcosis vary from dive to dive even under the same conditions - could the effect in the chamber be the same thing?

[NWGratefulDiver]

Doing a chamber ride to 50m doesn't necessarily produce the same narcotic effect as diving to 50m


Any idea why this would be :confused:

The way I see it - the air content/ratios is the same and the pressure is the same so it should produce the same level of narcosis. I don't have much experience with deep diving but I believe that the effects of narcosis vary from dive to dive even under the same conditions - could the effect in the chamber be the same thing?

A part of the perception of narcosis comes not from the nitrogen, per se ... but from what it's doing to the thinking part of your mind ... as evidenced from the fact that one way to deal with the effects of narcosis is to concentrate on a task, taking your mind off the fact that you're narc'd.

When you're sitting in a chamber, you're in an air environment, sitting comfortably (or uncomfortably), you're warm, it's brightly lit, and you're not exerting yourself. When you're underwater the conditions are considerably different. This may not make a difference physiologically, but it will make a big difference how you perceive your narcosis.

It's also true that cold, dark water will generally have a greater impact on how narc'd you feel than warm, clear water.

Much of the actual mechanics of what causes narcosis is not well understood ... but your environment definitely has an impact on how you feel it ...

... Bob (Grateful Diver)

[DennisS]

Doing a chamber ride to 50m doesn't necessarily produce the same narcotic effect as diving to 50m

We were taken down to 180 ft. I was very stoic, I wasn't going to get narced. They told us they were going to give us a few coordination tests. Everyone was very serious in the chamber, we were going to pass those tests.

We were at 180 ft, I felt fine. They had us touch our nose with our left hand, our right hand. This was easy, We were sitting in two rows facing each other and were told there were some more tests. They had someone get down on all fours. Lift your right hand, put it down, lift your right leg, put it down, lift your left paw (paw?), put it down lift your left leg, bark like a dog. I wasn't narced, I heard them say bark like a dog, Then I heard them say, "Hey Bill is Fido peeing on your leg" The tension was broken we started laughing and laughing, pointing at each other, saying it's not that funny, and laughing and laughing some more.

All it took was something to trigger it.

[PatW]

It would seem to me that if someone had a catastrophic loss of air at 60 meters, the ability of their buddie's air to get both divers to the surface would be pretty problematic. One can dive that deep. But if something goes wrong, it might be the last dive.

[Cave Diver]

It would seem to me that if someone had a catastrophic loss of air at 60 meters, the ability of their buddie's air to get both divers to the surface would be pretty problematic. One can dive that deep. But if something goes wrong, it might be the last dive.

Agreed.

[Cave Diver]

The tension was broken we started laughing and laughing, pointing at each other, saying it's not that funny, and laughing and laughing some more.

All it took was something to trigger it.

Somewhere, I have an old video where several of us did a deep dive and my buddy just started giggling uncontrollably. You can hear it in the background over the breathing and he's just chuckling away for no apparent reason.

[Tortuga68]

I was doing a 55m air dive once when the silly phrase "Noise pollution - the Silent Killer" popped into my head for no particular reason. I couldn't stop laughing for about 5 minutes :D



The way I see it - the air content/ratios is the same and the pressure is the same so it should produce the same level of narcosis. I don't have much experience with deep diving but I believe that the effects of narcosis vary from dive to dive even under the same conditions - could the effect in the chamber be the same thing?

Bob pretty much covered in his post immediately after yours - yes the dosage (time/pressure) is going to be the same, but you don't have all the other variables (water temp, viz, equipment etc) in a chamber dive. Also, you know you're doing a chamber ride and that there's really no practical chance of you getting killed or injured, so there shouldn't be any stress/worry which narcosis tends to exaggerate... so you tend to get more of the euphoric effect which CD mentioned

To address the second part of your comment, since there are fewer variables, I would assume the symptoms experienced in a chamber to be more consistent from dive to dive, but that's just my guess

[TSandM]

One can dive that deep. But if something goes wrong, it might be the last dive.

That was the story to which Bob alluded earlier. A bounce dive to 200 feet, but one of the divers got severely narced and was seen sitting on the bottom. His buddy went down and brought him up to where he became responsive again, but in the process, exerted himself until he ran out of gas. There is NO margin for error at those depths, on those small gas supplies.

[dumpsterDiver]

I've felt some narcosis at depths as shallow as 130 feet, but it is unusual that I feel anything until 160 feet. However, one particular dive, I came upon my buddy (we have a very loose buddy team when spearfsihing) and he had shot his spear into a rock. The 5-ft long shaft was some how horribly lodged into the limestone rock, with the flooper tip deployed (open up) after some penetration of the rock.

As I approached I could seem him working feverishly trying to slam the shaft back and forth as violantly as possible. Both he and I knew he would destroy the speartip, but the shaft might be salvagable. I decided to watch for a few moments, since watching people destroy gear and try to remedy mistakes they have made is kinda funny (both above and below the water).

This is extremely strenuous work and he was busting ass and swearing. :rofl3::rofl3:

After a little while, he gave up on the in/out slamming motion and now tried to rotate the shaft , he quickly bent the crap out of the shaft which instantly made the whole effort futile (snce he must have already destroyed the tip and a bent shaft is worth zero).

Instead of abandonment, he continued to furiously slam the shaft back and forth, twist it, bend it. Whatever...I totally lost it, this was perhaps the funniest thing I had ever seen in my life!

I somehow inhaled some water and started a violent and uninterupted coughing attack. Still, I just watched and continued to laugh my ass off with my mask half filled with water. After about a minute, I began to realize that I really was not breathing enough, I was just choking and laughing at his predicament. I had absolutely no concern for my safety at 130 feet; I have done similar dives hundreds of times, so I was not stressed at all at this depth.

Finally, I realized that I was begining to drown, that this was NOT humorous and I had better stop laughing and start to really concentrate on clearing my airway. It was not until that moment that it popped into my head that I must be narced (stoned) and THAT is why this scene was so funny. The idea had never even closed my mind before that narcosis was afecting me.

I concentrated on coughing and breathing and stopped laughing and was fine within 30seconds. Narcosis is like that for experienced divers, if everything is going fine, you may not notice anything.

50 meters is way too deep for an inexpereinced diver and 60 meters is enough to really ring your bell. Some people would become incapacitated at that depth.

[likestodive]

The world doesn't automatically come to an end at 130ft like alot of people seem to think. Everyone is right - the margin for error at 164ft (or 200+) is very small, but a bounce to 164ft isn't impossible by an means. In the 'bad old days' we used to go to Maracaibo in Cozumel and do la couple of minutes in the deep and then spend 45-50 minutes hanging at increasingly shallow depths. Not my idea of a good dive these days but at the time I thought it was. There are alot of people that have seen way deeper than 164ft on AL80's and not been anywhere near an out of air situation.

[Thalassamania]

I've had to make litteraly hundreds of bounces to 190 for very short tasks using a single 80 (and even a steel 72 back in the day). It's no biggie.

[Sas]

50 meters is ~164'. Outside the recreational limit of any agency I know of. A bit ill-advised as well.

25 minute total dive time maybe. 25 minute bottom time at depth on an AL80, doubtful.

The instructor may have taken him to that depth, but I wouldn't call it "recreational." Maybe he was doing an advanced class? Deco procedures?

BSAC tables are to 50m (5mins at this depth before you start incurring deco).

Not saying I think it is ok to have 50m as a recreational depth limit (not going to get into that) but just point out that one agency considers it recreational.

[miketsp]

SAA (http://www.saa.org.uk/) Dive Leaders are qualified to 50m, as are CMAS*** divers.

..snip..


My CMAS recreational tables go to 63m.....

[Sas]

SAA (http://www.saa.org.uk/) Dive Leaders are qualified to 50m, as are CMAS*** divers.


BSAC Dive Leaders are qualified to 50m also.

It just works differently to probably what a lot of people here are used to - I got deco training as part of my BSAC equivalent AOW (Sports Diver) for example, and more at Dive Leader as well.

[Lobzilla]

I've had to make litteraly hundreds of bounces to 190 for very short tasks using a single 80 (and even a steel 72 back in the day). It's no biggie.

The 'had' is the huge difference between what you did and the OP reported.

Let's just go through the 'gain versus potential pain equation' for the friend of the OP:

Gain:
(Bragging rights = positive)
+ (Skill development = zero)
+ (Knowledge development = zero)
+ (Development of prudent decision making = negative)

versus

(Potential pain = zero to huge)

Unless you 'have' to do this, in the line of duty for example, the low benefit of this act in even the best case is just not worth it.

If someone would tell me a story like this I would say: "Great, but if you really want to impress me come back in a week and show me how the darn backwards kick works".

[VooDooGasMan]

I have to agree, if you had a couple of dive buddy's that you know could get you to the surface in a hurrry, if you ran out of air in your tank, like these two buddy's.


YouTube - scuba diver attacked by 2 frogmen (http://www.youtube.com/watch?v=AVEN7qegJ3w&feature=related)



Happy Diving

[themagni]

Think your friend is pulling your leg.
I would lay money on 50 ft not M.
Often hear mistakes made by people who talk in imperial talking with others who work in metric.

That's probably what happened. He went to 50 feet and remembered it as meters.

Ask him what kind of light he was using. If he didn't have a flashlight at that depth, he wouldn't have seen anything.

[Cave Diver]

Ask him what kind of light he was using. If he didn't have a flashlight at that depth, he wouldn't have seen anything.

Maybe I missed the details of where this dive took place but I can't recall seeing it. Without that knowledge, that's a pretty big generalization. I've gone to twice that depth with no lights and had absolutely no problem seeing.

[NWGratefulDiver]

The world doesn't automatically come to an end at 130ft like alot of people seem to think. Everyone is right - the margin for error at 164ft (or 200+) is very small, but a bounce to 164ft isn't impossible by an means. In the 'bad old days' we used to go to Maracaibo in Cozumel and do la couple of minutes in the deep and then spend 45-50 minutes hanging at increasingly shallow depths. Not my idea of a good dive these days but at the time I thought it was. There are alot of people that have seen way deeper than 164ft on AL80's and not been anywhere near an out of air situation.

Going that deep on an AL80 is easy ... anybody can do it.

Coming back up is a bit more difficult. Sure, as long as everything goes right, ain't no big whoop. But let narcosis take your mind off what you're doing, or a bit of cold water get your reg freeflowing, of even something simple like a mask flood that causes you to lose buoyancy and sink back down while you're messing with it ... and you're a candidate for a Darwin Award.

Folks who do stuff like this are trying to prove something ... basic "Hey y'all, watch this" mentality.

I guess I just ain't that easily impressed ...

... Bob (Grateful Diver)

[dumpsterDiver]

That's probably what happened. He went to 50 feet and remembered it as meters.

Ask him what kind of light he was using. If he didn't have a flashlight at that depth, he wouldn't have seen anything.

???? There is no need to use a light in those depths if the water is clear.

I've been to a little over 1,000 feet and was still able to see over 200 feet with ambient light. (I was in a submarine)