"Guided" 200' dive with a single AL80?

[Cave Diver]

You all think that we were all on single 80's? You think we ALL were at 199'? The fact is I and the other instructor were on doubles. I was the only one that hit 199' and for :30. The others had max depts of 175', 165', and 160'. Julio in our group used only one tank. Jennifer shared air with us for the last :03 of the deco-stop. I barely used my second tank as well as Sean, the other instructor in doubles. We all are/were very good on our air and highly experienced. Some of you make out like I am taking beginners down to the 150' marker...and that's just not the case. And no...this was not a PADI dive. This was 4 very experienced divers doing a deco dive. We had all 4 done deco diving before. I understand everyone's concern, and will take all into consideration. But..if it makes you all feel better...I won't do that dive ever again.

This excerpt from your own website makes it seem as if they were right there next to you:

After he swam past me, he made his way past Julio, Jennifer, and Sean. I released my hand-hold and began to make my way up into shallower water. I glanced at my computer and the max depth reading was at 199ft. I was side by side with a Great hammerhead at almost 200ft! WooHoo! Now back to realtiy…finish the required safety stops and surface safely.

Only used one tank? Were ya'll isolating your doubles? If so, for what purpose?

I personally don't care if you do dives that are at the very least, questionable. I do however, object to you glorifying this type if irresponsible diving to someone else that might not know any better by posting it here and other places like this: The Deco Stop

 

[Hoosier]

It depends on the software or table used as well. For example with Dplan using standard 30/85 GF's, a 60 fpm descent rate and a 30 fpm ascent rate I get:

Descent to 200ft (3:20)
Level 200ft 5:00 (9)
Asc to 60ft (13) Air -30ft/min ascent
Stop at 60ft 1:00 (14)
Stop at 50ft 1:00 (15)
Stop at 40ft 1:00 (16)
Stop at 30ft 2:00 (18)
Stop at 20ft 3:00 (21)
Stop at 10ft 5:00 (26)
Surface (26).
Off gassing starts at 90ft

Gas Used 21% 47 cu ft (RMV=.6 for bottom and .4 for deco)

The points being

1. yes you could do it on an 80 (easily) but,
2. the real threat here is not so much the deco or the AL 80, but rather the combination of the two with regard to the execution of a deco dive without an adequate redundant gas supply to ensure you can ascend and do the required deco if your primary gas supply failed at the end of your bottom time.

With the same given RMV=.6 for bottom and .4 for deco


DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = Nominal

Dec to 200ft (4) Air 50ft/min descent.
Level 200ft 5:00 (9) Air 1.48 ppO2, 200ft ead
Asc to 100ft (12) Air -30ft/min ascent.
Asc to 60ft (13) Air -30ft/min ascent.
Stop at 60ft 0:20 (14) Air 0.59 ppO2, 60ft ead
Stop at 50ft 2:00 (16) Air 0.53 ppO2, 50ft ead
Stop at 40ft 2:00 (18) Air 0.46 ppO2, 40ft ead
Stop at 30ft 2:00 (20) Air 0.40 ppO2, 30ft ead
Stop at 20ft 4:00 (24) Air 0.34 ppO2, 20ft ead
Stop at 10ft 6:00 (30) Air 0.27 ppO2, 10ft ead
Surface (30) Air -30ft/min ascent.
Off gassing starts at 100.3ft
OTU's this dive: 18
CNS Total: 7.5%
56.4 cu ft Air
56.4 cu ft TOTAL


Yes, it can be doable if we tweak/config the plan, but it isn't easy plan for rec. divers to follow specially a middle water deco.... And, this "nominal" is too liberal to my taste.


However, who cares. It is their life, not mine. :mooner:

 

[ScubaAndDreams]

You all think that we were all on single 80's? You think we ALL were at 199'? The fact is I and the other instructor were on doubles. I was the only one that hit 199' and for :30 seconds. The others had max depts of 175', 165', and 160'. Julio in our group used only one tank. Jennifer shared air with us for the last :03 of the deco-stop. I barely used my second tank as well as Sean, the other instructor in doubles. We all are/were very good on our air and highly experienced. Some of you make out like I am taking beginners down to the 150' marker...and that's just not the case. And no...this was not a PADI dive. This was 4 very experienced divers doing a deco dive. We had all 4 done deco diving before. I understand everyone's concern, and will take all into consideration. But..if it makes you all feel better...I won't do that dive ever again.

You shared air w/her... yeah ok...very experienced divers....genius just genius. I am sure that was part of your GAS MANAGEMENT plan before the dive too right?

 

[xiSkiGuy]

You all think that we were all on single 80's? You think we ALL were at 199'? The fact is I and the other instructor were on doubles. I was the only one that hit 199' and for :30 seconds. The others had max depts of 175', 165', and 160'.

The fact that you think it makes it OK that the single tank divers stayed in the 160'-175' range shows how you are both ignorant and untrained for this type of diving.

Julio in our group used only one tank. Jennifer shared air with us for the last :03 of the deco-stop. I barely used my second tank as well as Sean, the other instructor in doubles.

Do you know what gas planning is? Do you understand Rock Bottom? Did you do any gas planning for this dive? The obvious answer is no or you would understand how stupid it was. And were you using independent doubles or manifolded doubles? Because either way you were doing something wrong to have only used one of your two tanks.

We all are/were very good on our air and highly experienced. Some of you make out like I am taking beginners down to the 150' marker...and that's just not the case. And no...this was not a PADI dive. This was 4 very experienced divers doing a deco dive. We had all 4 done deco diving before.

Going into deco a few times is no substitute for deco training. I don't know a trained deco diver anywhere that would have done that dive. Nevermind the air vs. trimix aspect of it. . .

 

[Nemrod]

I don't believe the dive in the video was a well planned dive nor do I recommend 200 foot dives but you guys make this stuff out to be more than it really is.

80 cf tank
Desend to 200 feet--4 minutes (TT 4 minutes)
Look around for 1 minute (TT 5 minutes)
-----------------------------------------------------------------------
Total BOTTOM TIME is 5 minutes ( beginning of descent to beginning of ascent)
------------------------------------------------------------------------
Ascend (60 FPM) to first stop at 60 feet--2 minutes and 20 seconds (TT 7:20)
Stop 60 feet for two minutes (TT 9:20)
Ascend to 30 feet (30 FPM)--plus stop at 30 feet for five minutes--- 6 minutes (TT 15:20)
Ascend to 15 feet (30 FPM)--plus stop at 15 feet for 10 minutes---10 minutes and 30 seconds (TT 25:20)
Ascend to surface--slowly--say 1 minute
-------------------------------------------------------------------
Total Time of dive is 26:20

You can do this on an aluminum 80--not saying it is smart or easy or for the meek or inexperienced or practical or any of that. Just that it can be done.

If I recall the original Navy Tables allow 5 minutes (actually 190 feet I think) with direct ascent to surface--that is five minutes from beginning of descent to beginning of ascent, would allow a nice look see on bottom. Haul tail down and when the clock ticks 5 minutes begin immediate ascent at 60 feet per minute to surface. That would be a dive of a total duration of only about 8:20 or so, toss in a safety stop at 15 of five minutes and your still under 14 minutes. This is a no deco dive.

N

 

[STOGEY]

The fact that you think it makes it OK that the single tank divers stayed in the 160'-175' range shows how you are both ignorant and untrained for this type of diving. Do you know what gas planning is? Do you understand Rock Bottom? Did you do any gas planning for this dive? The obvious answer is no or you would understand how stupid it was. And were you using independent doubles or manifolded doubles? Because either way you were doing something wrong to have only used one of your two tanks. Going into deco a few times is no substitute for deco training. I don't know a trained deco diver anywhere that would have done that dive. Nevermind the air vs. trimix aspect of it. . .

I think some of the problem here lies not with the chap that did this dive, but with those who are reading about it. It's guys like he that push the limits that really set the boundaries of what the rest of us do. So maybe some people here are just a little jealous that this guy had the nutts to do this.

 

[Vayu]

My opinion is that since certified instructors were on this dive they should have understood how a dive can be completed without having to share air or any other breathing gas. All divers should have known. No harm no foul maybe? At least the shark is cool.

I think some of the problem here lies not with the chap that did this dive, but with those who are reading about it. It's guys like he that push the limits that really set the boundaries of what the rest of us do. So maybe some people here are just a little jealous that this guy had the nutts to do this.

I just have to say that 200' is hardly a depth limit for diving. Much deeper dives into much more hazardous conditions have been done generations ago. The only thing these divers are doing is enjoying a dive while ignoring their training.

Interesting choice of music for the video. "There is no way back from here"...

 

[PlayaCountryBoy]

I think some of the problem here lies not with the chap that did this dive, but with those who are reading about it. It's guys like he that push the limits that really set the boundaries of what the rest of us do. So maybe some people here are just a little jealous that this guy had the nutts to do this.

Thank you! I feel the same!

 

[TSandM]

I think some of the problem here lies not with the chap that did this dive, but with those who are reading about it. It's guys like he that push the limits that really set the boundaries of what the rest of us do. So maybe some people here are just a little jealous that this guy had the nutts to do this.

I was going to stay out of this, but this is too much.

We lost someone who by all accounts was a very nice young man, here in Puget Sound, not too long ago. Why? Because he did a bounce dive to 200 ft on a single Al80, and somebody got into trouble down there, and he tried to help.

The issue is not whether you can safely execute a dive to 200 ft, on air, on a single tank. You can, if everything goes smoothly and there aren't any problems at all. But if anything goes sideways, you're down there, significantly impaired by narcosis and SEVERELY limited by gas supply.

There were two people down there in doubles, hopefully with more than sufficient gas for the proposed dive AND rock bottom reserves, and I would assume that the thought process was that the person in the single tank could make an air-sharing ascent with one of the guys in doubles if it were necessary, as it proved to be. Personally, I would never make a dive plan that required me to share gas to complete it. I HAVE made a gas plan that included the possibility of sharing gas for a while to even out supply, but that was a no-deco dive with no overhead, so if for any reason I was unable to share gas, I could turn the dive or surface at any point.

My husband used to do deep dives on a single 72 (on air). You couldn't get into much trouble, because you couldn't stay there long; when you popped your J-valve, you made your 60 fpm ascent. Nobody had heard of rock bottom, and nobody did stops. They survived. It doesn't make it an intelligent choice in today's diving world, where we know better and have better gases and better equipment to make deep diving safer.

If the single tank diver is really that experienced, he or she needs a bit more education, I think.

 

[FIXXERVI6]

....The fact is I and the other instructor were on doubles......I barely used my second tank......

How do you barely use your second tank?

What kind of gear config where you using? Do you wear independant doubles and breath one tank till low/empty then switch to the second?

If so I have a real life story for ya about that kind of config.