Tomcat was totally right, and I have to apoligize, it's alot easier to treat the dives like repetitve dives with no surface intervals. I generally use the NAUI tables for multi level dives, which require a 10 minute surface interval. If the SI is less than 10 minutes the first dive, SI and second dive is all lumped together as one dive.
I compared the Residual Nitrogen Times in Table 3 to the values in Table 1 and found that only Q 70 and L 50 differed. The values were 1 minute longer on Table 1 than on Table 3. I would guess this is some kind of rounding where they round up on Table 1 and down on Table 3 for added safety.
Zept brought up another interesting point, why there is a slight difference in pressure groups between the wheel and table. I agree with him that it is probably personal differences on where hte arrow crosses the line with The Wheel. I have heard PADI changed their tables slightly several years ago, that may be where the difference lies too, if The Wheel is a different edition than the table.
I'm willing to bet the table and the wheel are from the same tables. Why would PADI go through the cost to develop new limits, and then have one product be an inferior table to the other. I wish I had a wheel, because I could convert it to table form and see if the values were the exact same as the table. I can't find an inexpensive one on line, and I'm not paying $50! I'm going to Florida for classes the end of May (yippee!), and I'm sure they will let me have a few hours with their wheel, so I'll try it then, if nothing else.
Maybe the best way to handle repetitve dives with the table is to round up a pressure group for each calculation, to add the safety you get when you have doubt an arrow crosses the line with the wheel. For Problem 1 that would make the diver a V after Dive 1, a H after the SI, and a U after Dive 2.
Also, I didn't know when I wrote the problems, the official instructions for the wheel require at least 30 feet in between levels so the multilevel dive at 70', 50' and 35' is a violation of the rules.
When my buddie and I were poor college students we planned multi level dives on the tables all the time. Now that we have an income above the poverty level we have dive computers and use the tables only to plan about how long we want to stay at a level, so we know if we're going to spend 10 minutes or 35 minutes at 90'.
-Katrina
