Split from Exploration dives without a computer

[Cacia]

ok, onfloat. The place where you did your last class, lets skip the name. Those guys take divers on air to the Sea Tiger everyday and they are the local DIR shop, I just was trying to figure out how thay do all the things they do and still .... see? I am not trying to make a problem it is just that every "DIR" diver I have ever known has one set of what they "say" and then they either solo, or use computers, or take divers that have 10 dives to very deep dives on air as part of their business/income model. I do not want to discuss said shop, but I am laying out an example I know you can follow because I think this is the real mystery to people like Dennis and I with DIR in general. I know PADI is much worse so I am not being critical. Just trying to "get it". There are certain things I want from DIR divers.

Having said that, I wish divers experienced with thinking the tables through on every dive and making adaptations for multilevel, changing dive plans would explain the nuts and bolts of how they do this like what has happened in this thread and the "mother thread" as SB, Thal, Onfloat, jeff have done. Even Charlie's 100 psi per 10 is very helpful and frankly, I have never heard this before. I know it because I do it...but the "news you can use" angle does not happen enough around here and I wish there was more of this. Even if you disagree with someone's approach, I still learn quite a bit from a guy who decides to run an excel spread sheet and demonstrate how he thinks his planning through.

 

[TSandM]

I guess that's why, when somebody started a thread about, "Are you a DIR diver?", nobody admitted to being one. It's like a state of grace . . . you can describe it, but nobody ever actually GETS there.

 

[Cacia]

well, in my mind, I always compare it to "being" a Christian. If you think about this a minute, it makes sense. Someone can be a thief and if they accept Jesus...they still get to heaven, still get to be a Christian. But if you don't, even if you live a good life...you don't get into heaven. (or insert any religion)

Now, if you accept DIR, and come on here and do not get it right, but you try and be DIR compliant, as long as you espouse "DIR" then you are good, still in the club. But take another diver, says well....I am not totally DIR (andy, for example) becuase I really prefer this hose on this side, then, even if he is actually more DIR compliant than "the other guy", he gets told he is NOT DIR and people really want to make him stop associating with the name. Just very interesting to me. Kinda like the very good catholic who tells the priest that she uses birth control.

onfloat, what does your math look like that tells you .21 O2 increase to .32 gives a 20% increase in depth? I know you are right, I just want to be able to calculate...say .36 EAN depth advantage in my noggin.

 

[PerroneFord]

State of grace? Oh man, I can hear the demons clawing at the walls now... They'll be coming soon.

 

[PerroneFord]

Now, if you accept DIR, and come on here and do not get it right, but you try and be DIR compliant, as long as you espouse "DIR" then you are good, still in the club. But take another diver, says well....I am not totally DIR (andy, for example) becuase I really prefer this hose on this side, then, even if he is actually more DIR compliant than "the other guy", he gets told he is NOT DIR and people really want to make him stop associating with the name. Just very interesting to me.

In my limited experience, this is NOT how things have worked. But then, there seems to be a chasm between internet DIR, and the real thing.

 

[Diver Dennis]

I think that is very true Perrone. Internet DIR is different from the real world DIR, as Bob said, he has friends that have been diving this way long before DIR was around and although more DIR compliant than most, they do not really refer to themselves as DIR. ALthough DIR might not be for me, a lot of what they do is. I think it gets a bad rap sometimes for being an all or nothing system which I don't think it is, is it? It seems there is flexibility there.
Just to qualify my question, I mean open water DIR divers, not advanced cave divers and overhead environment guys.

 

[TSandM]

Although the schisms leave it somewhat unclear who is who and what is what (and who gets to define what is DIR, anyway?) I loved what Joe Talavera had to say when he was up here teaching the Essentials course. He said basically that there are things (gear, procedures) that affect the safety and function of the entire team -- for example, using a long hose and bungied backup, or accepting the team diving principle. Those need to be right. And then there are things like how I attach the bolt snaps to my light head. I can do what works for me, and it shouldn't affect the team, and if, for some peculiar reason, my teammate needs to clip off my light for me, he can most likely sort what I've done out very quickly . . . and it's unlikely anybody's survival is going to depend on getting my light clipped off by somebody else in thirty seconds, rather than a minute.

I thought that was a pragmatic approach to the issue.

 

[Thalassamania]

So, if I understand the table your using that's the minimum starting pressure in your tank.

No ... that's bingo air (e.g., my buddy and I are, at that point, carrying just enough gas to get both of to the surface without blowing any of out planned stops).

Rock bottom on a 130 ft dive for 2 divers requires about 40 cubic feet of gas and on an AL80 that is 1500 psi. A dive like that is not DIR.

Rock bottom with bingo=1500 is 40 cubes. Who gives a flying DIRigible?

You didn't say what type of tank you were using and so your psi amounts maybe for something bigger or doubles??

Problem as stated ... AL80.

 

[Thalassamania]

Correct, but not an "informal" turn pressure, that's bingo ... as in time to go, RIGHT NOW!

 

[Thalassamania]

Your rock bottom or minimum ascent pressures are pretty clear, and aren't too different than just adding 200psi to the very simple "100psi per 10'" that many divers use for AL80.?

Not too different, but they are actual calculations based on the max depth and the SAC rate of each diver.

But please clarify the deco planning a bit. You are just treating the entire dive as being at max depth. Correct??

Planned to stay within the U.S.N. no-D limits with a 3 min stop at 1/2 max depth, a 3 min stop at 15 feet and enough extra gas for a 2 at 10 as might be required if we'd just slightly overstayed our welcome.

A couple of specific examples. Let's say you went down to 60' for 20 minutes and still had 1700psi (that's about 0.6cfm SAC), and then dipped down to 100'. ?

The SAC I used for these calculations was 0.7 for each diver. We're into the dive at 60 ft ... can we descend to 100 ft? Yes, but then we'd start up 25 min into the dive or bingo @ 1200 psi.

1. Per your plan, is your stay at 100' limited to 5 minutes max, such that you do not exceed the 100'/25 minute limit??

If we were 20 min into the dive already then that is correct, touch 100 feet and you start up at 25 minutes.

2. Per your planning, if you start off a dive to 100' for 15 minutes, and then ascend to 60', do you still hold to a total bottom time of 25 minutes? If you do take into account the shallower depth later in the dive, how does that factor into your calculations?

Touch 100 feet and you start up at 25 minutes. But this kind of planning is really for working dives where it is as important be able to control you repetitive dive group as anything else, since it is rate to take a day in the field with a single task.