first deco dive

[Kingpatzer]

To me there is one issue, and one issue here only:

You did not plan your dive nor did you dive your plan.

All the training, gear, and skill in the world won't fix what can go wrong when you fail to put it to proper use.

Take the courses, dive lots, take up the offer for some local mentoring, and have a blast. But in the future, please don't make up dives on the spur of the moment while at depth and with half a tank on your back.

 

[Garth]

Until I took adv nitrox /deco procedures I never, not once incurred a deco obligation. The closest I allowed myself was 2 min NDL. I also never ran out of air.
So what right?
Well, I guess the way I look at it it seems as though a missed NDL is a mishap that shouldnt be happening often. I suppose you can justify it anyway you like but it doesn't seem like good practice.

 

[redacted]

I like the idea of testing your computer in deco. I have done it myself and will do it again with increasing deco requirements. But, with a little planning, such tests can be done by putting only your computer into deco and not yourself. I use nitrox for my gas and used 2 computers with the test computer set for air. (Same thing could be done with tables.)

Incurring an unplanned and unnecessary deco obligation just does not seem like a good thing to do.

 

[Garth]

If you know your computers algorithm this isn't necessary. If you have the tables on air you know the difference.

 

[TSandM]

Going into deco is not a sin, and you won't end up with a scarlet "D" on your forehead.

I did a little backgas deco before I did my "technical" class -- but I'd done three fairly intense classes involving critical skills and problem-solving at depth and as a team before I did it. And the deco was PLANNED, and the gas supply to do it was planned. The more deco you rack up, the more dubious doing it on a single tank is, both from a gas supply standpoint and a lack of redundancy. But if you have the education and the training, doing was BDSC is doing isn't reprehensible. The key is that it is pre-planned. Where deco gets people into trouble is when it ISN'T planned, and the diver is confused, doesn't have the information to know what to do next, doesn't have the gas to do the time, or can't handle any issues that occur during the time when it is unsafe to surface.

 

[joe8mofo]

I love how there are people who enjoy acting as Scuba police, even it if is only to hear themselves speak. To the Scuba police: go vilify someone else for doing something far worse than going into mild-deco with a sufficient amount of gas.

I intentionally went into mild deco on a planned dive to 130' earlier this year with a sufficient amount of backgas. After I hit deco and stayed for 2 minutes, my buddy and I made a slow ascent to 70' for a minute deep stop and slow ascent to 30 feet where the deco obligation cleared. After a 4 minute stop at 20 ft and a 4 minute slow ascent to the surface; I exited the water with 1/2 a tank full of air. It is different to know in the forefront on your mind that you cannot safely ascend to the surface should something happen; this requires a complete change in how the dive is planned, in fact it may even increase one's respect for properly planning and executing dives.

I think this discussion is proof that at least some recreational divers can properly plan and execute dives which may incur a mild deco obligation safely. Additionally, steel tanks are great, but they also enable one to get into trouble if they are not cognizant of their dive plan.

 

[MXGratefulDiver]

I think this discussion is proof that at least some recreational divers can properly plan and execute dives which may incur a mild deco obligation safely. Additionally, steel tanks are great, but they also enable one to get into trouble if they are not cognizant of their dive plan.

Nah ... steel tanks got nothing to do with it. In fact, it's even easier to get yourself into real trouble with those oversize beer cans they use at most scuba resorts around the world ... because they don't hold a lot of gas, and you ain't really in trouble until you realize you don't have enough gas available to make it to the surface safely ... :shocked2:

Gear choices don't get people in trouble ... making decisions without understanding the potential consequences of those decisions gets people in trouble. That's why the "scuba police" are usually so adamant that proper training and experience are so important.

In diving, the answer to almost every decision you can make is "it depends" ... the trick is knowing what it depends on ...

... Bob (Grateful Diver)

 

[tracydr]

The two things I would worry about the most in doing this is lack of redundancy(one tank, one reg) and the lack of understanding of the computer tables. You can incur some really long deco times by going a small amount over your NDL if you've been doing multiple dives with short SI.
What happens when you or your buddy have a reg malfunction and you have to hang for 30 minutes on what's left in a single tank?

 

[LiteHedded]

The two things I would worry about the most in doing this is lack of redundancy(one tank, one reg) and the lack of understanding of the computer tables. You can incur some really long deco times by going a small amount over your NDL if you've been doing multiple dives with short SI.
What happens when you or your buddy have a reg malfunction and you have to hang for 30 minutes on what's left in a single tank?

psh

I would just get out of the water and go run a marathon

 

[MXGratefulDiver]

What happens when you or your buddy have a reg malfunction and you have to hang for 30 minutes on what's left in a single tank?

... you come up as slowly as possible, get yourself on O2 as quickly as possible, and hope there's a chamber nearby in case you need it ...

The better answer, of course, is don't put yourself in that situation in the first place.

Understand, however, that just because your computer says you have a deco obligation doesn't necessarily mean that your body thinks so. Computers have built-in conservatism ... some more so than others. Depending on the profile you dived and the algorithm used, some will start reducing your deco obligation at moderate depths as you ascend, while others will continue piling on more minutes until you reach a much shallower depth.

I used to own both an Oceanic and Suunto computer. Just for giggles once, I strapped them both on my right arm and went for a fairly aggressive dive. The Suunto went into deco while the Oceanic didn't even come close. At one point in the dive, there was a significant (28 minutes) difference between the deco obligation on the Suunto and the NDL remaining on the Oceanic.

Which one's right? The answer is neither ... they're both just acting on a mathematical model. Which one most closely represents the nitrogen levels in the various tissues in my body? I have no idea ... neither would anyone else.

The question is, how safe is safe? Depends on a lot of mitigating factors the computer knows nothing about ... like your age, physical condition, amount of hydration, type of exposure gear you're wearing, exertion during the dive, and a host of others.

That's the problem with relying on a computer ... you're measuring with a micrometer, marking with a laser, and cutting with an axe ...

... Bob (Grateful Diver)