Diving beyond cert?

[inquis]

One simple rule of thumb when diving a single AL80 is to leave the bottom at:

GasPressure_psi = 10*(Depth_ft+30)
GasPressure_bar = 3*Depth_m

These are easy to compute approximations to more rigorous calculations. (FWIW, they do not exactly agree with each other, but are pretty close at 100 ft/30 m.) They are, however, fairly conservative, and even moreso if you round depth up for easier computation (e.g., at 86 ft, use 90 ft and leave at 1200 psi).

That said, I would encourage everyone to learn to compute things on your own, as there are some parameters you may find overly conservative as you gain experience. (For example, I personally feel 10*Depth_ft to be sufficient for myself and an instabuddy.) It's also possible the above is insufficient for your needs.

Regardless, I'd say the above is more useful to OW divers than "be back with 500 psi".

(This allows for a total RMV of 2 cuft/min, 1 min at depth, and a safety stop. While simple, it is about 100 psi short of a more rigorous calculation at 130 ft. Alternatively, it agrees with a 1.9 cuft/min RMV at 130 ft. The metric version will be about 6 bar short at 15 m.)

 

[Dapper Dan]

You'll probably find, if you're going on any sort of charter from a reputable shop, they'll have their own rules. Here for dives beyond 60' it's "Must be AOW or better, must have 3 or more boat dives, must have computer, must have SMB, must have dived in the last year. " YMMV

If it's your own boat or your buddies boat, you're on your own pretty much in America. There's things you ought to know to safely dive deeper like gas consumption, narcosis, etc. My bottom time on the U-352 at 116 feet is 18 minutes. My bottom time on the Theo Parker at 60 ft is 60-70 minutes. I always get back on the boat with at least 30 PSI

If you aren't going to take the PADI AOW class at least buy the PADI AOW book and read and understand it.

 

[happy-diver]

Well I have no overblown paragraphs, that would make it appear that I was giving responsible advice
complying with what my fellow scubaboardians think is expected in the basic forum, just some words

I got OW certified (PADI) in May and have only been on a few dives since. I'd like to go diving again soon, but where I've been invited is generally 60-100' where all the interesting stuff is. I seem pretty comfortable, and am not terribly worried about the depth. I am signed up for AOW next month already. I'm wondering if there's any critical reason I shouldn't do these dives? Dive buddy is really experienced and reassuring, and I'm not above aborting at the first sign of problems or me being uncomfortable. Thoughts please?

Just do it, or never learn, and realise if you do not push past where you are, that is where you will stay

 

[34109411]

The most important thing is knowing you have sufficient gas for you and your buddy to ascend to the surface in the case that one of you suffers catastrophic gas loss and you have to share gas to the surface.

I wrote a dive planning doc for my area:
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but the concepts are universal. If you know the site, have a map, go through the process and see how comfortable you are once going through this excessive exercise. The point of the document isn't memorization, but to develop a plan for new places and being comofortable throughout the dive as you monitor your gas consumption and compare to expected cylinder pressures at different points of the dive and always abiding by min gas.

wow i am amaze by your document ! it seem you have access to 1000 dives sites compare to me, lucky you are.

 

[Blackcrusader]

This post -- along with most of the others in this thread and on ScubaBoard in general -- does not understand that the OW cert is to 130 feet. It confuses a certification depth with a recommended maximum depth that depends on your training and experience.

When I mention this I get told off lol You get more experience by diving with more experienced divers.

 

[arew+4]

When I mention this I get told off lol You get more experience by diving with more experienced divers.

The major difference between a 60' no deco open water dive, and a 100' no deco open water dive, is 40'. All else being equal, vis, temp, current, etc, the additional/elevated/aggravated risk factors are the potential for narcosis, the accelerated gas consumption, and the abbreviated NDL. As long as the OP, is aware of these risks, is mentally and physically fit, has a reasonable dive plan, an experienced buddy and clear communication protocols, he should be fine. Is it ideal to go to 100' on your tenth dive? Probably not. Is it prohibitively dangerous? No.

 

[submergenarcosis]

If your buddy is experienced then go for it. At 100’ you can’t stay that long so you need to monitor NDL constantly.
Air consumption may also be something to keep an eye on. Follow your computer.

 

[MB NZ]

I'm the opposite of the SCUBA Police, I don't know what that's called, but hopefully someone will come up with a cool name. I had a lot of first time diving experiences without training, but less than 10 dives, you are a baby in diving terms, take it easy! Sorry to be a blunt spoilsport.

 

[MacDuyver]

I got OW certified (PADI) in May and have only been on a few dives since. I'd like to go diving again soon, but where I've been invited is generally 60-100' where all the interesting stuff is. I seem pretty comfortable, and am not terribly worried about the depth. I am signed up for AOW next month already. I'm wondering if there's any critical reason I shouldn't do these dives? Dive buddy is really experienced and reassuring, and I'm not above aborting at the first sign of problems or me being uncomfortable. Thoughts please?

I did 110ft a week after getting OW certified. I’m not gonna universally recommend it in hind sight.

In my case I’d been diving with the DM/instructor before, he felt comfortable taking me down with the guidance of “stay within arms reach of me and do exactly what I say/do.” So I did.

I don’t really recommend it without qualifiers though.

 

[inquis]

In an OW class -- with at most 3 dives under your belt -- you may have dived to 60 ft on a training dive. It's baffling how a limit *during a class* is conflated with how deep someone can go *after a class*.

My OW instruction was very clear: stay within the guidelines of the Recreational Dive Planner after the class (130 ft normal limit, 140 ft emergency limit). You will continue to learn as you dive, so grow your experience gradually beyond that of the class up to the limit of recreational diving. (That max depth hasn't changed with the advent of computers.)