mikemill
Contributor
Heh I only work in sets of 10^3n 
Gas planning and the associated math - controversies over need and how to teach
- Thread starter Thalassamania
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OP
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What's the volume of your tank? Err ... let's have that in mega-parsec barns please.
How many decimal places are required? Are we using US or English barns?
OP
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No. It was actually a subtle reference to the variations in the US & British imperial system of measurements.
So we've gone from a very small (10-28 m2) measurement of area to Swallows. Are you being rude, or is it me. :mooner:
OP
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No, not rude, but nobody ever expects the Spanish Inquisition.
nudge, nudge; wink, wink; say no more.
Since a Thal response to an excerpt from one of my posts is the first item in this relocated thread, I will clarify, or correct as the case may be. I never intended to suggest, nor did I indicate, that teaching gas management was somehow beyond PADI standards. I can't spesk for Kris or others, and have nothing to contribute to the Thal and Kris show. I hope that teaching gas management isn't exceeding standards, because I do just that for OW students, including those who come to me after completing eLearning. I think the concepts of SAC, effects of pressure on gas consumption, and the ability to plan a dive beyond merely establishing a turn pressure are important; the calculations involve simple algebra, which reasonably capable people can perform, and the RDP is less intuitive than gas calculations.
Yes, if failing to pass such a test was applied as the (sole) criteria for denying certification, then it exceeds standards. That was my the point. I have no problem testing. I give sample problems that constitute a 'test'. Using that test result as a criteria for denying cerification would be difficult to justify, if a student who I failed, solely because of that, protested to PADI. (Yes, yes, any instructor has more than enough latitude to deny certification to any student that he/she thinks has not 'mastered' a skill or concept.)
Now, to extend this, it is interesting that the automobile gas consumption analogy has been repeatedly used, and endorsed as relevant to this discussion. I agree that it is. How many high school driver education courses require students to calculate gas consumption and driving range? None in NC and none in VA, that I am aware of, and I suspect few if any do. How many state driver license written examinations require such calculations be performed? (I think I know the answer, but I still pose the question.) Understanding braking distances - yes. Gas calculations - no. How do most drivers learn to estimate driving range? The driver education analogy is actually quite relevant to diver education.
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At the end of the first OW classroom session, I give my students homework--a series of story problems in which a novice diving couple go through a couple of dives and encounter problems. The questions require them to apply differnt things they have learned in the class.
I wait to go over them while we are in the context of learning the tables, and I do ask a table question. After a day of shallow diving (first questions), my mythical divers are doing a wreck dive to 100 feet. I tell how long it took them to get to the wreck, and I ask how long, according to the table, they can stay on the wreck before they ascend. Students have no trouble with this.
The following questions introduce more issues, though. When the wife signals to ascend because they have reached their NDL, the husband gives her a different signal. What is it? Why?
As we talk through it, students realize he has slashed his hand across his throat to indicate he is out of air. They see how they can estimate how fast these divers are going through their air from the previous dives, and they see that the couple should have known that they did not have enough air to stay more than a few minutes on the wreck and still reach the surface with an adequate reserve.
That leads to a talk about the importance of this sort of knowledge and planning, and I show them a very simple way to get a sense of their SAC rates for this purpose. Mostly they see that this is important to know. They also see why they should not just go down to such depths without more practice and training.
In the AOW course, I give the full and complete SAC rate information and planning.
I wait to go over them while we are in the context of learning the tables, and I do ask a table question. After a day of shallow diving (first questions), my mythical divers are doing a wreck dive to 100 feet. I tell how long it took them to get to the wreck, and I ask how long, according to the table, they can stay on the wreck before they ascend. Students have no trouble with this.
The following questions introduce more issues, though. When the wife signals to ascend because they have reached their NDL, the husband gives her a different signal. What is it? Why?
As we talk through it, students realize he has slashed his hand across his throat to indicate he is out of air. They see how they can estimate how fast these divers are going through their air from the previous dives, and they see that the couple should have known that they did not have enough air to stay more than a few minutes on the wreck and still reach the surface with an adequate reserve.
That leads to a talk about the importance of this sort of knowledge and planning, and I show them a very simple way to get a sense of their SAC rates for this purpose. Mostly they see that this is important to know. They also see why they should not just go down to such depths without more practice and training.
In the AOW course, I give the full and complete SAC rate information and planning.
I know we didn't agree on a previous thread, but after reading your post on how you walk your students through gas planning, it occurred to me that I never learned gas planning (other than the standard 'surface with 500PSI' thing) in either my OW or my AOW classes. I know gas planning now, but it was something that came out of reading The New Science of Skin and Scuba Diving and not any instruction that I have received. NWgratefuldiver also has a great article on the same subject.
To make a long story short, I am going to integrate your idea on gas planning into my future leadership endeavors in my diving. Thanks for the good advice.
