Going deeper, safely

[MXGratefulDiver]

Decompressing on a computer alone is frighteningly dangerous. Without the tables that DevonDiver mentions you have no plan for when the computer suddenly dies. Now what? I, too, generally dive the schedule that my predator gives me (as it benefits from multi-level and multi-gas diving) but you have to have a back-up timing and depth device and set of tables to interpret that data should your primary (computer) fail.

It depends ... when the computer dies, do you have a backup? Tables aren't going to do you much good either unless you have a means of monitoring depth and time. And if you have those ... and assuming we're still discussing the 165-foot dive the OP mentioned ... then you don't need tables if you have a working understanding of how decompression works.

I stopped cutting tables about a year or so after I started doing staged deco dives. In the 150-220 foot range, ratio deco works nicely ... and requires neither tables nor computer. All it takes is a bottom timer ... and if you're going to be doing deco dives, it's always a good idea to take along a backup ...

... Bob (Grateful Diver)

 

[opperud]

I am new to diving and have no plan to do some thing crazy, but i wish to understand, from what i read bounce diving is unsafe,but i don't full understand all what makes a bounce dive a bounce dive, one thing is the single tank, right?
But what about lets say doing 50m or 165 feet. With a tank of ean 28-32 and a tank or 2 of air(ean 21) And having a dive plan and deco info all calculated before, and more experianced divers along, Is that too considered unsafe, or is that just tec diving.

Lastly is having the skill doing a padi or ssi course or can one get those skills from other experienced divers and taking small steps, with in you capasity.

I don't want to start a discussion about this course or that course, or how to kill yourself. But one about how to stay alive, be safely and intellegently ,slowly learn to go deeper.

Hi all! New on this board, and English is not my native language, so please bare with me

First of all, what are your motives for "going deeper"? It allways scares me a little when divers states that without any other reason than going deeper than they have been before.
When someone ask me if technical diving is fun, I tend to tell them no. As you venture deeper than 30-40-50-60 whatever meters, all that happens is that the ambient light becomes dimmer, there is less and less marine life, the colors fade away except from in the middle of your lightbeam and your ascent takes 2-3-4-5-6 times longer than the time you can actually dive on whatever it is that you are diving on.
If, however, there is a wreck, a cave or something specific that you want to see that happens to be at that depth, the reward can be well worth the effort I have never understood deep diving on a reef or a wall

Now, i tend not to draw a thick red line between "technical" diving and "recreational" diving. It serves no useful purpose, and can easily distract divers from acknowledging the actual risks associated with that particular dive, in the end of the day, its all diving. Stating that Technical diving is more dangerous than recreational diving is at best imprecise when taken out of context.

As an example: The dives you have been doing in the +/-40m range with air only would not typically be considered "technical", whilst if I did that same dive only with 21/35 and a decobottle of 50 or 100% o2, it would. Yet, I would argue that my dive was safer than yours

However, the deeper/longer you go, the more severe the result of any unforeseen happening. As you start going past 30'ish meters, your available time to solve problems before you start taking on mandatory decompression and/or your breathinggas supply runs out is becoming increasingly shorter.
People do admitably respond differently to the effect of narcosis, but what doesn't vary is that past this range your brain will not perform at it's best if diving air or nitrox. That is not to mention the gas density/co2 considerations related to diving heavy air at these depths, witch is what can really create problems for you.
An incident that would be considered a inconvenience at 15m could be much more dramatic at 50, let alone diving on air.
The way from hero to zero is much shorter.

Taking a formal class with a talented instructor would/should give you the appropriate tools for diving this depths and beyond with an acceptable level of risk. This does cost time, money and effort, and it is not and does not have to be for everyone.
If, however, you are ready to take on the challenge economically and time/effort-wice, the revards are in my opinion well worth it


Best,
Bjørn

 

[gsk3]

It depends ... when the computer dies, do you have a backup?

Hi Bob,

In my mind the problem with a computer isn't a lack of a backup (as you point out, you need to know depth/time to use tables or RD!), but in the lack of planning it can foster. Particularly in the context of the level of (non-)training we're talking about in this thread, it would be fairly easy to incur a much bigger deco obligation than you have the gas to support--even without a freeflow or other supply failure.

 

[dumpsterDiver]

Some very good posts in this thread, but my personal feeling is that a person with 25-50 dives should NOT be making these kinds of dives..either with (or without the appropriate training and gear). The OP is just starting out in diving, it takes TIME and dives and experience to begin to recognize what you can and should do when diving.

The advice should be: No you don't take 32% to accelerate deco from 140 feet, and you don't do deco dives until you have had a few near misses, you've had the crap scared out of you and also been presented with a diving situation that was past your comfort zone and your were able to master the mental and physical demands of that dive. You really need to prove to yourself that you can handle challenging stuff underwater.

Lastly, the new diver needs to be made aware of the fact that, for a vast majority of new divers: Your training SUCKED, it was so bad you don't even realize it yet.. so go slow, take your time and there is no rush to go past 100 or 120 or 140 feet! Find a good buddy, read some good information and do a bunch of dives that will probably not cripple you if you make a beginners mistake.

 

[mathauck0814]

It depends ... when the computer dies, do you have a backup? Tables aren't going to do you much good either unless you have a means of monitoring depth and time. And if you have those ... and assuming we're still discussing the 165-foot dive the OP mentioned ... then you don't need tables if you have a working understanding of how decompression works.

I stopped cutting tables about a year or so after I started doing staged deco dives. In the 150-220 foot range, ratio deco works nicely ... and requires neither tables nor computer. All it takes is a bottom timer ... and if you're going to be doing deco dives, it's always a good idea to take along a backup ...

... Bob (Grateful Diver)

I did say that you would need a backup depth and timing device. Because the sites where I'm doing deco diving are fairly constant, it works just fine to have the schedules in my wet notes (as they don't change so long as my gasses and plans are static). I'm admittedly not using ratio deco. I am also not advocating that you would ever reactively dive the plan that your computer is giving you, rather that you make a plan with your software of choice and then use that as the more conservative back-up to the deco schedule you're being given by your computer.

 

[Mr Carcharodon]

Some very good posts in this thread, but my personal feeling is that a person with 25-50 dives should NOT be making these kinds of dives..either with (or without the appropriate training and gear)..

The OP was not saying he was going to do a 165 foot dive today. He was asking how to get there and was not asking to be slapped on the wrist. Scholding is almost as bad as telling OW students not to dive outside their training, which would leave them swimming around the shallow end of the pool forever.

 

[eternaljonah]

thanks every one for your feedback.... here in pondy there are huge deserts of sand and the best diving in on a wall that starts at 32m till about 40m that where i've done most my dives. i do tend to become a little obsessed in what i do and have been diving every weekend 4 times and since the local lds is closing( for a month) i'm on my way to the andamans( average depth 12-25 meters) to dive... i was under the impression that once i got to the 100-150 dives i would be ready to start and explore a little deeper, there is a hole here that starts at 33m and i would one day( When i'm ready) to have a look inside. but i understand that i better get a much bigger theoretical understanding of deco, and dive planning. i think i will start to use my computer as back up and do my dive plans,ndl and so on for each dive before on the boat....
i just love being underwater its gives me peace of mind. and i want to thank every one again for their comments it had a sobering effect on me.... we have an expression here "slowly but surely"
just a last thing my ow,aow instructors were very good and covered alot of materiel. i thanks them.

 

[tengsr]

Don't do dives that you don't understand - and acknowledge there is plenty you won't understand.

Don't confuse confidence with over-confidence.

Dive conservatively. If unsure, don't do it.

Plan your dives properly - NDL, gas and all applicable contingencies (doing so will eliminate most deep diving ideas)

Remember that a plastic cert card won't save your life if something goes wrong at depth - your ability to dive deep isn't determined by a qualification, it is dictated by your relevant experience, training, knowledge and preparedness.

I wish I had internet while I was doing my certification, cause there was me and a girl who quit. So it was just me. On my 3rd open water dive and my instructor was at 95 fsw, I started getting nervous a 75 ft but he kept waving me down, then he got got agrivated when he saw me me surfacing with 350 psi later in the dive. Its ok though cause he said he was shocked that I was so low, I was going up regardless whether he noticed or not, he was a buddie that needed to cover a thousand miles a dive, and my rental reg couldn't deliver the air I needed and I learned fast that hitting the purge will give you more air to breathe

 

[ajduplessis]

<snipped>

When someone ask me if technical diving is fun, I tend to tell them no. As you venture deeper than 30-40-50-60 whatever meters, all that happens is that the ambient light becomes dimmer, there is less and less marine life, the colors fade away .......

......<snipped>

Marine life does not always deteriorate as you go deeper. We dives sites in the 50-60m range that has more life than reefs at 20m. Diving the right sites at various depth is the trick. The following pics were taken at 105m (340ft) and show a beautiful reef and a Coelacanth (Latimeria chalumnae) thought to be extinct. Marine habitats change depending various factors, you just need to find the right combo.

 

[VooDooGasMan]

tengsr that is an Interesting OW class, the Instructor had one student and this is how it went, must of been somewhere in BC. well at least you had the most experience to monitor gauge and surface. Unfortunately there are to many instructors out there that teach this way or many other unsafe ways that is why there are so many accidents.

Tengsr glad you are still diving, the girl quit and lucky enough you lived through your class. why did you not have internet did this happen 20 years ago, or recently. Just trying to justify how long instructors have been teaching this way. I would say recently as I think instructors are just new divers right now, even if a person is old always look to see when there instructor card was issued, not to say they are better at teaching just more experienced.