Depth

[finbob]

I am a rookie diver, an older man with plenty of flab. On a recent dive in the Philippines, the Divemaster got carried away and took me down to a depth of 52M. Although it was an exhilarating experience I believe an unnecessarily dangerous one. He was later disciplined for it. My question is should we have decompressed as we ascended? We had the 3 min at 15' but is that sufficient? Was I in danger?

 

[Crush]

finbob,

I am relatively new to diving, so perhaps I am too conservative. Here is what I think:

I really hope that was a typo! 52 m = 171 feet, which is well below the recreational diving limit of 140 ft. We can't calculate deco obligations without knowing the time spent at 170 ft, plus rates of ascent and descent.

Are you basic OW? If so, depending upon your cert agency, your maximum recommended depth may be only 70 feet. I can't say that you were in danger, but the possibility for danger was exacerbated by your depth and relatively new diving status.

In my mind you are living proof that often a DM can do something ill-advised and get away with it. I tend to observe the onset of nitrogen narcosis at about 110 feet and have never gone below 140 ft. At least you were with a DM who (in theory) could have bailed you out of an emergency at depth. However, in my mind, he demonstrated poor decision making skills by taking you that deep.

 

[Jim Lapenta]

What was your exact profile? As to being dangerous yes it was. Had you ever been below even 60feet before? What size tank were you using? What is your SAC rate? What would the plan have been for deco? I'm guessing you do not know the answers to some of these. For that reason you should not have allowed that to happen. As a certified diver you and you alone are responsible for your dive plan. At the very least when you approached your recommended limit it was your responsibility to say stop. I suggest you read this thread:

http://www.scubaboard.com/forums/ne...ering-diving/283566-who-responsible-what.html

What you have just described is unforunately an all too common experience and it is due IMO solely to poor initial training in which you did not get the info you need to make an informed judgment as to the safety of such a dive. 53m is approx 170 feet to those of us who do not have the time or inclination to work it out in feet. As such a dive to that depth on air, besides risking extreme narcosis which it sounds like you experienced to a degree, is not on any recreational planner. I will therefore just assume (and this is by no means a recommended plan) a total bottom time of say 10 minutes. On V planner with a conservative setting of 5 this looks like this:
DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 5

Dec to 171ft (3) Air 50ft/min descent.
Level 171ft 6:35 (10) Air 1.30 ppO2, 171ft ead
Asc to 100ft (12) Air -30ft/min ascent.
Asc to 60ft (13) Air -30ft/min ascent.
Stop at 60ft 1:18 (15) Air 0.59 ppO2, 60ft ead
Stop at 50ft 2:00 (17) Air 0.53 ppO2, 50ft ead
Stop at 40ft 3:00 (20) Air 0.46 ppO2, 40ft ead
Stop at 30ft 3:00 (23) Air 0.40 ppO2, 30ft ead
Stop at 20ft 6:00 (29) Air 0.34 ppO2, 20ft ead
Stop at 10ft 10:00 (39) Air 0.27 ppO2, 10ft ead
Surface (39) Air -30ft/min ascent.

Off gassing starts at 91.1ft

OTU's this dive: 16
CNS Total: 6.3%

57.3 cu ft Air
57.3 cu ft TOTAL

The numbers in the 3rd column are decompression stops that are required for a dive of this type. How much air did you have left when you came up? If something had gone wrong at 171 would either of you had enough air to get BOTH of you back up safely? If you do not know you had no reason to allow the DM to take you there and make no mistake you did allow him to. Those are also some pretty fast descents for a new diver.

Now if you did a bounce dive which is just going down and coming right back up it is even stupider and would look like this:

Surface interval = 1 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 5

Dec to 171ft (3) Air 50ft/min descent.
Level 171ft 1:35 (5) Air 1.30 ppO2, 171ft ead
Asc to 100ft (7) Air -30ft/min ascent.
Asc to 10ft (10) Air -30ft/min ascent.
Stop at 10ft 1:38 (12) Air 0.27 ppO2, 10ft ead
Surface (12) Air -30ft/min ascent.

Off gassing starts at 60.5ft

OTU's this dive: 9
CNS Total: 3.4%

You could do it w/o a safety stop but this is even more dangerous IMO. I would not attempt this dive type of dive profile. Too many things can go to crap very fast. The DM should have been disciplined yes but so should you be disciplining yourself. YOu should do this by getting more training and from different people. The first ones did not get thru to you what exactly it is and isn't that you should be doing as a new diver.

 

[redacted]

You say the DM "took" you down but, unless he grabbed you and dragged you down that is probably the wrong choice of words and the wrong mindset on your part. I suspect the DM guided you down and you willingly followed. So you went down to that depth of your own free will. You could have declined to accompany him and called the dive as soon as you reached your limit.

If the time at depth was short (less than 5 minutes) and the ascent was nice and slow, then it is unlikely that your dive involved a missed deco obligation.

Live and learn. Dive safely.

 

[Scott L]

That's a tough situation for a new diver. The answer is emphatic hand signals to protest or to signal thumbing the dive. I have had instructors take me in overhead environments not in the dive plan and they received a firm tug on their fins to get their attention to stop...

 

[Doc Intrepid]

"Was I in danger?"

Yes, you were.

As Jim explained, one big reason why is response time and options. If something goes dreadfully wrong at 30', a new diver has some time/gas to deal with their issue and/or, if necessary, can swim to the surface to resolve things.

At 171', not so much. You don't have time to respond in, nor gas to respond with, and you can't really swim to the surface while dealing with other issues. No options.

More experienced divers create options for themselves when going to these depths, but rookie divers would not have those same options. Hence you did what we call a "trust me" dive. If all goes well, fine. If not, well...we read about you in the paper.

Live and learn,

Doc

 

[dmoore19]

Ok folks here is a question. Not blasting the OP but if I had been there at +/-80 FSW, because of my own set of rules, I would have tried to get the DM's attention. If that failed I would have thumbed the dive and returned to the surface alone. The question is, if this were to happen what other options does one have except to surface solo?

 

[Diver0001]

I am a rookie diver, an older man with plenty of flab. On a recent dive in the Philippines, the Divemaster got carried away and took me down to a depth of 52M. Although it was an exhilarating experience I believe an unnecessarily dangerous one. He was later disciplined for it. My question is should we have decompressed as we ascended? We had the 3 min at 15' but is that sufficient? Was I in danger?

Diving really deep can be exciting but it's not for everyone and it's a bit of a taboo in some circles. I don't think I'll repeat what the other's said, although i'd recommend reading Jim Lapenta's post in some detail.

My input would be this. What you did is like driving 160km/h (100mp/h) on a public freeway with someone in the passenger seat telling you when to speed up and slow down. It can be a real hoot but it can also end in a bad way in real hurry. If you're comfortable with that then that's your choice but most divers tend to be more risk averse.

As for your deco profile. We can't evaluate that given what you wrote. The tables we had in the early 80's (IIRC) gave an NDL of 5 min at 50m but generally decompression protocals (and behaviours) have become more conservative since then. Obviously since you didn't get bent then the only thing we can conclude is that you didn't get bent. I think, however, that a lot of people these days will also conclude that what you did isn't wise and you were probably lucky.

R..

 

[Doc Intrepid]

"...I would have tried to get the DM's attention. If that failed I would have thumbed the dive and returned to the surface alone.

The question is, if this were to happen what other options does one have except to surface solo?"

None. Assuming you are disinclined to go deeper.


First, if you are diving with a dude so out of touch that he hasn't realized his "dive buddy" has thumbed the dive, this should tell you something about his situational awareness.

Second, unless he has some irrational urge to go deep by himself, once he realizes his student is swimming for the surface his next move would likely be to follow.

It is unwise to follow someone who is diving in some way that makes you uncomfortable. Your discomfort is telling you something worth paying attention to. If you have no other options (e.g. communication attempts have failed), thumb the dive and ascend, by yourself if necessary.

 

[redacted]

Before the diver surfaces, solo, he could simply stop and see if his buddy also stops his descent and rejoins him. Give it a minute or two of watching, or until the descending DM disappears.

None. Assuming you are disinclined to go deeper.


First, if you are diving with a dude so out of touch that he hasn't realized his "dive buddy" has thumbed the dive, this should tell you something about his situational awareness.

Second, unless he has some irrational urge to go deep by himself, once he realizes his student is swimming for the surface his next move would likely be to follow.

It is unwise to follow someone who is diving in some way that makes you uncomfortable. Your discomfort is telling you something worth paying attention to. If you have no other options (e.g. communication attempts have failed), thumb the dive and ascend, by yourself if necessary.