Split from Exploration dives without a computer

[Cacia]

I have a pretty good one. But it ends at personal attacks.

just make up a code name or like i tell my son "think of him running naked down the road"

RH, somebody needs that for an avatar! its being wasted.... I need it for my collection.

Perone, if i can deal with personal attacks, trust me, so can you. Buck up baby.

attacks? so what? 100 years ....all new people.

he went out on a limb folks, so what? tough love...a big part of DIR though perrone.

 

[PerroneFord]

there is a huge difference between posting something as an answer to a question and posting a question.

If you want an answer ask a question and everyone will benefit from the correct answer.

Yep, you're right. Thanks.

 

[TekDiveGirl]

*snicker* Watch out Perrone -- RHM is a tough chickie!

 

[grazie42]

Since we´re know back in "friendly" territory and discussing gasses and deep air...below is an example of a dive we plan to do, next time I go diving and my reasoning behind my choice of gas...Just thought I´d throw it out there to hear your opinions...

30min dive to ~150ft (45 mtrs really):
1: Air +50% (for deco): 74 mins & 45m/150ft ead (duh!)
2: 26% ean +50%: 64mins, & 42m/140ft ead
3: 26/10 +50%: 60mins & 35m/115ft ead
4: 26/20 +50%: 58mins & 28m/95ft ead

I know the "getting out of the water faster"-argument rubs some people the wrong way but I don´t make plans that I can´t follow, even with a flooded drysuit. With water temps below 40F that is a real factor. That´s why I won´t do this kind of dive on air (here).

So 1 is out. 2 is ok, for me, ead is still deeper than what agencies recommend but for me it won´t keep me from diving. Dive 3 is 15$ more expensive (than dive 1 & 2) but also leaves me "less drunk" and would be my "preferred mix". Dive 4 is 30$ here and, to me, not worth the expense unless I expect "harsher conditions"...

 

[Cacia]

now, there is a practical man.

 

[Snowbear]

So divers who are not Trimix certified cannot diver deeper than 100 feet?

Where did I say that? Anyone can do whatever they want, including a solo deco dive to 127' on air from an AL80. Is it a good idea? That's up to the individual.

Someone mis-stated something about GUE/DIR gasses and I responded. I'm in no way telling anyone what to do.

 

[TheRedHead]

I realize that Snowbear..I was asking for the DIR viewpoint since the original statement was originally posted in the DIR forum, no?

You never made that statement, I just inferred it. Can't we chill a bit?

 

[Thalassamania]

Nor is doing a 130' dive on air in the first place.

For me, and the people I dive with it is a general consensus that 130 on air is trivial, which is not to say that we’d distain using NOAA I for such a dive. While it may be DIR to use trimix at 130 it is not de rigeur. I, for one, do not like the unforgiving nature of helium decompression. There is a trade off here between sobriety and offgassing. So a look around, warm, tropical dive would get air or NOAA I, but a complex, highly task loaded, cold and dark dive to 130 might have me looking at 21/35 or something similar.

Nor is counting on your SPG to be accurate down to 100psi,

I use a old Genius, because it is accurate down to 100 psi

Nor is doing a dive to 130' on an AL80 (though I don't think he specified the tank size?)

AL80 was specified in the original question. Even with a SAC rate of 0.7 that’s a 10-minute dive with 1500-PSI Bingo. It may not be DIR but there’s nothing wrong with it. If that’s not enough gas for you to reasonably make a 10 minute, no required stop dive to 130, I’d very respectfully suggest that your primary concern should be how to reduce your air consumption, there are some excellent yoga techniques that I've seen work wonders, while my regular dive buddy swears by relaxation mediation and dive pevisualization to bring her SAC rate down.

Nor is doing a 3 minute stop at ½ max depth and a 3 minute stop at 15 FSW with a 30fpm ascent rate

If you have a better plan I’d love to hear it and reason(s) it’s better, I’ll change that in a flash, my spinal column has been very, very good to me and I’m very attached to bowel, bladder and sexual function.

Nor is using the "NDL" on a computer as a basis for altering a dive plan

I don’t know what you are referring to here, but I've always felt that the most effective divers I know are those who used all the information that is available to them. The problem that most divers have is in understanding what the "NDL" on a computer means and how it relates to the table based information that they should also have. Lets not be neo-luddites just because of these difficulties. In my experience, given time, practice and effective mentoring most divers can, in fact, learn to think their way through such problems.

 

[Thalassamania]

NDL
"Every dive is a deco dive" is an oft repeated phrase. The risk from an immediate ascent only slowly increases as one approaches and then exceeds traditional NDL. A few extra minutes spent in the ascent and stops on the way up is much more important than whether your are a couple minutes one way or the other of NDL. I use a computer with a bargraph that shows loading as a fraction of maximum allowable NDL loading. Meanwhile, I do some tracking in my head vs. the PADI limits (I dive often enough that it isn't all that hard to keep in memory this relatively small set of numbers, particularly since my computer has essentially the same numbers for NDL).

We do the same thing, more or less.

My on-the-fly calculations are similar, but include some seat of the pants and gut feeling sort of approximations that allow for multilevel profiles. In one sense, I really just know whether my loading is light, medium, heavy, or loaded to the gills.

I wish I could honestly raise my right hand and swear that I don’t do that, but I do.

I also have a feeling whether this is in the fast compartments or the slower ones. (A square profile deep dive rapidly loads the fast compartments, but OTOH, they will also offload quickly. A square profile dive to 70 or 80' is what in real life leads to a dive with the heaviest loading still left after one of my standard ascents).

Now … there’s the meat of this issue. If the question had been leave the surface, scurry to 130 spend 10 and up, I’d say sure. I’m more concerned by the down for 20 at 70 and want to go to 100, we’re off the 5 and 10 minute tissues and that gives me a little itch back behind my eyeballs.

I wouldn't go so far as to say that I am actually tracking average depth numerically, but on the other hand, I do keep a crude mental tally of both overall dive average depth and the average depth over the last 10 minutes or so. My deep stops depend only upon average depth in the 10 minutes or so before starting my ascent, so even on a dive with 130' max depth, my first stop will be 40' is my last 10 minutes was 60 or 80'.

I’m fairly rigid in my deep stop depth, your way might work better … I need to play on the simulator a bit.

I also use the bargraph of an Oceanic hockey puck computer to confirm my gut feeling on loading levels (or vice versa -- it's debatable whether my internal tracking is primary and the computer a backup, or it's the other way around).

I do like the bars, I was (and am except for it’s size) an ORCA lover.

I also have tucked away in memory a handful of precomputed multilevel dive profiles ---- once you start factoring in gas consumption and rock bottom on an AL80, you can get pretty close to most acceptable profiles with just one or two profiles per starting depth. I.E. Having precomputed multilevel dives for 130' max, 100' max, and 80' max covers most of my diving. The precomputed profiles are from the PADI Wheel (or my equivalent "Flat Wheel" table), but you'll end up with pretty much the same profiles if you do them in Decoplanner or V-Planner.

For sure. I use an Excel spreadsheet that all in need plug are the diver’s SAC rates. The only real “multilevel” diving that I do is for bluewater collecting, and that just strictly done by computer and good sense (basic plan is to always have 5 minutes no-D remaining on the computer and your tethered to a safety diver on a ten meter lead.

ASCENT PROFILE
My ascent profile is neither as biased towards the shallow side as the old PADI 60fpm + 3 min at 15'; nor as biased towards the deep side as the old GUE 1 minute every 10' from 80% of ata/75% of depth all the way to the surface. My ascent profile attempts to emulate with just 1 ascent rate and 3 stops, what comes out of a gradient factor program such as Decoplanner (with low gradient factors) or out of a dual phase/bubble model program such as V-Planner when using high levels of conservatism.

1. Stop depths. For ascents from 80' or less, 1st stop is 40', 2nd stop 25', 3rd stop is a 20' to 8' glide. For 100+' these become 50', 30', and 20' to 10'.

2. Depending upon how heavily loaded I am and how bored I am with what's around the stop depths, the basic ascent is basically 1 min at firsts top, 2 minutes including move time up to the stop for 2nd stop, and 3 minute for 3rd stop. The minimal ascent is a minute at 1/2 depth, 3 min in the 20 to 10' stop. If heavily loaded, my stops become 2 minutes at 40', 3 at 25-30', and 4+ minutes at "safety stop" depths. If my loading is mostly in the faster tissues (coming up directly from deeper dive), then I bias things a bit towards the deeper stops. If heaviest loading is in the medium speed compartments (such as from a 50 minute air dive to 60' flat bottom), the everything get moved a bit shallower to 40' / 25' to 20' / and 15' to 5'.

3. Nominal ascent rate between stops is 30fpm, but I don't sweat it too much. How I really control my overall ascent rate is by looking at my computer, taking the current runtime, rounding it up to the next minute (doesn't show seconds), and adding to it my total ascent time (typically 6 to 9 minutes). That give me the end time of my 20-8' safety stop/glide. The end of my 1st stop is 1 or 2 minutes, plus ascent time to 40' or 50'. End time for my second stop is obviously between those two times, and is closer to the 1st stop ending time than the surfacing time.
All of this may sound very complicated, but you will be surprised at how easily it all comes together if you try it the next few times you start an ascent. After a while, you really just have to remember starting time, what you have chosen for surfacing time, and after than you just glance at your computer or bottom timer and you pretty much can automatically tell if you are at the depth you should be for that runtime.

We’re on the same page here, I’ve just simplified it a bit since I tend to shun required stop diving whenever possible. My system has been fine tuned to that sort of diving. When I have to make required stops dives (beyond 2 at 10) our approaches converge.

ROCK BOTTOM

As I posted about 3 years ago, this extend ascent requires about the same amount of air that is required for an emergency problem solving + ascent with a panicked diver, so there is no need to increase rock bottom numbers to account for the slow ascent and extra stops.

I just use the simple 100psi per 10' of depth, but never less than 700psi. This is true rock bottom, not just a "let's start ascent somewhere around this psi". Rarely do I ever get to rock bottom.

Perhaps it is the hubris that will let the gods kill me, but I do not give any specific consideration to ascent with a panicked diver, and emergency problem solving is really just, “my regulator or yours?” We drill those ascents and don’t find that our ascent rate drops (much the opposite problem, that’s when you really have to think about slowing it down).
We try to never go bingo, it does happen rarely and always calls for a post-dive conference to consider if getting to bingo was really necessary.

The title of the thread is "Exploration Dives Without A Computer". My method could be used without a computer, but in reality is more along the line of how to intelligently dive WITH a computer.

Here here!

I suspect that there are other divers out there that have developed or evolved similar methods of controlling their profiles, but have not seen anyone post their methods.

Now there are at least two of us who've done so.

 

[Snowbear]

For me....

The post you quoted was in response to someone pointing out that your answer was not DIR. At the time, the original poster had asked for DIR answers. That's irrelevent in this thread now.