hand signals from diver to boat (in clear water)

[Mike.D]

An ow dive can be planned as a deco dive.

We are not talking about an accident as in 'oh I forgot to look at my computer and now I'm in deco'. We are talking about an emergency that delays your ascent time so that you end up violating your NDL's, thereby inducing a deco obligation. Eg your dive buddy gets wrapped up in fishing line and needs help being cut out, you run out of NDL's now your in deco. No overhead, no 'unintentional' going into deco by not following your training.
Would you potentially kill your buddy because you don't want to go into deco and just leave him at depth tangled in fishing line?


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[TSandM]

50 bar is 750 psi, and I assume you are discussing the ubiquitous Aluminum 80, so we are talking about roughly 18 cubic feet of gas. Assuming a depth of 15 feet, or 1.5 ATA, and a SAC rate of 1.0 (novice diver, stressing out because he's in deco), you've got about twelve minutes of gas.

You asked the right question, too. The big risk of going into deco on a single tank is that you will not have the gas to do the time. Deco, in and of itself, is not dangerous (although executing staged decompression dives DOES raise the DCS risk). After all, people do deco all the time and do just fine. The difference is that those divers PLANNED their deco -- they knew exactly how much obligation they would have, and they planned to have more than enough gas to get it done (as well as to have redundant sources, should a single one fail). Recreational divers have neither the planning nor the redundancy, nor the gas to be safe with a significant decompression obligation, and they often don't have the skills either to do the time, or to handle any problems which might occur underwater, before they are safe to surface.

For all of these reasons, it is very wise to avoid incurring a decompression obligation as an open water diver. And as others have said, if you are paying attention to your gauges, it won't happen.

 

[beanojones]

An ow dive can be planned as a deco dive.

A recreational dive cannot be planned as a deco dive, because that is a dive without direct access to the surface. Treating deco as anything but a hard ceiling, just the same as inside a cave or a wreck interior is doing tech diving without training, and it is often punished by boat owners, dive operators, captains, and dive guides because it is just plain irresponsible to those people whose livelihood is being threatened by diving far beyond one's training, experience, and gear setups.

Once one treats a deco obligation as a hard ceiling and does it as a tech dive, then that operators who are fine with properly trained and equipped tech divers will of course not have a problem with those divers doing a tech dive. Of course if someone gets in with a single tank and reg, then they are back to being a recreational diver regardless of training and experience. My regulator (BCD, Tank, computer, mask) does not being a magic fail-safe device just because I am a tech instructor. Which is why tech divers are carrying multiples of each if those devices when doing a tech dive.

Here's a better question for the OP since there are clearly some bad misunderstandings happening here, and people are being incredibly selfish in being casual about diving beyond the limits of their training, experience, and equipment:

Instead of thinking about being OOA and trying to hand signal the boat for air or other planned foolishness, imagine a far more common real world example:

Imagine what happens when the boat has to leave the mooring to rescue someone adrift at the surface, and you lose your mask. How would one even have any idea of anything at that point? Can't see the gauge, can't see the computer, can't tell your who your buddy is...

Deco diving is tech diving, period. There is no reason ever to go into deco unintentionally. People get away with all kinds of stupidity diving. I can go play soccer in the street without getting hurt, sometimes.

Please go read the link. I'll post it again. I do not agree with everything Chatterton has to say about everything, but this one is dead on topic:
http://www.johnchatterton.com/2013/03/19/accomplished-bad-divers/

It really is really, really bad form to make others risk their livelihood instead of being responsible for one's safety, especially when there is a proper way to do these things. Captains have to make nice to customers, but they do have families to feed, and treating their livelihood with such disregard should get such a diver kicked off the boat, literally on the spot, as in that diver should be left adrift in the ocean, instead of making a captain risk his own livelihood to enable their stupidity. If a diver is forcing others to risk their livelihood to ensure the foolish diver's safety, then that foolish diver is being a bad person.

 

[Mike.D]

I meant OW dive as in an open water environment not OW certified.

Regardless, I graciously accept defeat...

That's an interesting link you posted.

And for the record, I do not condone nor suggest people dive beyond their limits and training at any point.


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[rivers]

A recreational dive cannot be planned as a deco dive,

Correction, in the PADI world, a recreational dive cannot be planned as a deco dive. I can think of at least 2-3 agencies off the top of my head that teach deco at a recreational level

 

[ballastbelly]

I did not ask the question because I was planning on trying deco. I am not tech certified. I am only OW certified, aspiring to do my AOW next vacation (next year?)

In the meantime if an instabuddy's hand gets pinned in a crevice, and the group has fallen back in the current, how am I going to respond? By writing on my slate that I am OW only, not rescue certified? Or make him sign on the slate a risk liability release with his free hand ?Or am I going to use every tidbit of info to think of a way out for both of us, even if it involves deco.

One of you mentioned against using information from a random group of strangers, well I think even an instabuddy is a random stranger in a sense,& that fate has decided to cross our paths. Peace

 

[rivers]

I did not ask the question because I was planning on trying deco. I am not tech certified. I am only OW certified, aspiring to do my AOW next vacation (next year?)

In the meantime if an instabuddy's hand gets pinned in a crevice, and the group has fallen back in the current, how am I going to respond? By writing on my slate that I am OW only, not rescue certified? Or make him sign on the slate a risk liability release with his free hand ?Or am I going to use every tidbit of info to think of a way out for both of us, even if it involves deco.

One of you mentioned against using information from a random group of strangers, well I think even an instabuddy is a random stranger in a sense,& that fate has decided to cross our paths. Peace

If SHTF, the number one rule is to not make a second victim (yourself). So if your numpty insta-buddy has gone and stuck their hand in a crevice, neither of you can get it out, and you're at minimum gas, what are you going to do? It's not an easy decision to make, is it? Personally, I'd send up a blob, with note attached to send down someone with a spare tank, if available, and start making my ascent on the line. If you are out of gas by the time you free your buddy, you're no good to them. And you've just made a second victim.
Also, don't go sticking your hand in crevices! wtf?

 

[Tigerman]

If SHTF, the number one rule is to not make a second victim (yourself). So if your numpty insta-buddy has gone and stuck their hand in a crevice, neither of you can get it out, and you're at minimum gas, what are you going to do? It's not an easy decision to make, is it? Personally, I'd send up a blob, with note attached to send down someone with a spare tank, if available, and start making my ascent on the line. If you are out of gas by the time you free your buddy, you're no good to them. And you've just made a second victim.
Also, don't go sticking your hand in crevices! wtf?

However if I've got plenty of gas but running close to my NDL, my dive just turned into a deco dive - BY ACCIDENT.
That said, I know my gas consumption so Id know how much gas Id need in order to stay x minutes at y depth and Id also be willing to surface with less than my usual 60-70 bar in the tank if I had to..

 

[Mike.D]

However if I've got plenty of gas but running close to my NDL, my dive just turned into a deco dive - BY ACCIDENT.
That said, I know my gas consumption so Id know how much gas Id need in order to stay x minutes at y depth and Id also be willing to surface with less than my usual 60-70 bar in the tank if I had to..

Exactly.


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[rivers]

However if I've got plenty of gas but running close to my NDL, my dive just turned into a deco dive - BY ACCIDENT.
That said, I know my gas consumption so Id know how much gas Id need in order to stay x minutes at y depth and Id also be willing to surface with less than my usual 60-70 bar in the tank if I had to..

I've no problem going into deco. I also know my gas consumption. But if there is an issue with my buddy being stuck because they've done something stupid, and I am at minimum gas, and there is no chance of them being freed in the next minute or so, I'm going up. Minimum gas is what is needed to get 2 people to the surface while completing all stops. If I have less than minimum gas left, there is quite a good chance that there is not enough gas left to get two divers to the surface. If I have more than minimum gas left (and chances are I do as I dive twins), then by all means I will stay and do what I can (a blob will have also went up with a note at this point to send someone down). It's once I hit minimum gas that I'm out of there.