biscuit7 once bubbled...
I just finished my AOW, I still don't know how to use the wheel. I still don't know how to plan multi-level dives on paper. I'm not unique in that respect. The plan I gave in the above example isn't unique. This is a typical Caribbean (and probably elsewhere) kind of dive. Tons of people do that dive, in some form or another, every day in dive destinations around the world.
Most instructors don't teach the weel. I don't think it ever really gained popularity. I think it's good to at least look at one if for no other reason that it illustrates what is going on in a multilevel dive at least in the context of that model. I have one you can look at. Multi-level planning is something that can be addressed by an instructor in any class (hint...hint)
Short of signing up for the PADI Multi-level Diver Specialty, where is a diver to get the information to avoid the "trust me" dives? Does DIR-F cover it? Do other agencies cover it in their advanced certificates?
I think dive planning is taken a little too light in most training. It's almost as if it's assumed that you'll be following a guide. On the other hand some instructors make the planning aspects of a dive a priority in any class. Of course a plan doesn't have to be complicated just appropriate.
There are a whole bunch of people telling me to toss the computer but no one is giving me a way to fill in the knowledge gaps so that plan is feasible!
We've talked about this a lot here. Apparantly GUE isn't goind to address compuerless multilevel diving outside of their tech and cave classes. I'm sure they have their reasons. It isn't hard to come up with a way to do it if you really studdy the tables and/or profiles using decompression software. I can't say that I am familiar with exactly what GUE teaches but I have my own ways. Outside of GUE I'm not sure how an instructor can teach any of these methods because they directly conflict with the instructions given for table use. That doesn't mean that it won't work just that a PADI instructor for instance would have nothng to fall back on to justify their methods.
The following is for discussion purposses only.
Just to satisfy your own curiosity on the subject I can think of a couple of things you can do. 1, look at some of Uncle Pugs threads. He has talked about what he does including profiling. 2, It isn't recommended to use most dive table to plan multi-level dives but it's been done. Look at how the table works and see if you can estimate what your RNT and resultant NDL will be moving from a deeper level for a certain time to a shallower level. You will notice a definate pattern. 3, You will also hear divers refering to what they call their profile depth (as apposed to max depth). If you play with some decompression software or even the tables you'll see that you can plan a multi level dive and a single level dive and get the same (or very close) answer using a depth that turns out to be the average depth. IMPORTANT...by average I don't mean the mean of the depths but a weighted average that takes the time at each depth into account. I can show some math to make this clearer if you want.
Going through these excersizes, if nothing else, will help give you a feel for what your computer will say before it says it and some intuition into what you will calculate on the table before you calculate it. Kind of like using estimation when doing math to know if the answer the calculator gives you makes sense. Useful I think even if you stick with the computer.
You might say these methods don't seem very precise. You are right but again if you play with some decompression software you'll see that by running the same dive but setting user setable parameters differently you can get dratically different answers. Which is the right one? So where does the precission come in? In the end you decide. As many point out most tables and computers don't reflect the latest thinking in decompression either. Others point out that what we have works. Not always. Also you are the only one who has a feel for what you shouldn't do (conservatism).
All that said, there are other things to consider like being in control of and aware of what you actually did on the dive. You can't estimate anything if you don't know where you were and for how long. Other things like good ascent procedures, gas management and how you conuct yourself before and after dives.
I don't think there are any secrets but I also don't think there are any short cuts.
I had an interesting conversation once with a GUE trained diver. We were discussing profiling and he used the example of the dive he had just done. He stated his max depth, the overall shape of the dive and what he used as a profile depth. I commented that it didn't seem very precise and that I didn't think using an average depth was valid based on the math of the model. His response was that I could use a deeper profile depth if it made me feel better.
I think and some one please correct me if I'm wrong but one of the resons these guys won't give up the secret is because there isn't one and it's so simple. Yet, if all the pieces arent there a person could really mess up by just jumping in the water without using tables or a computer.
Again all this has been just conversation. I'm not qualified to teach anything other than the accurate use of tables, computers and decompression software as outlined by the agencies I teach through and this isn't it.
I would certainly like to hear comments on my take on all this from the people who were tought to dive this way.
