I don't know if the e-learning goes through the tables any more or not.
They are not very intuitive, really. But here's a brief description of how it goes. Assume you have done a dive to 50 feet for 30 minutes. You find the column in the upper left section that says 50 feet, and go down to the box that says 31 minutes (because you always round deeper). Go across, and discover you are an "I" diver at the end of that dive.
Now you have a one hour surface interval. Go across the "I" row to the numbers on the right. You will find a box that says 44 - 105. Your 60 minutes SI falls in that range, so you go down that column, and discover you are a "C" diver at the end of your surface time.
Now you go to the back of the card, or the lower of the two cards on the link. Find the column headed by "C", and the row corresponding to the depth of your next planned dive. Let's say you're going back to that wreck at 50 feet . . . your adjusted no-deco time is 63 minutes. This contrasts with the 80 minutes you would have had on the first dive (that you didn't use, because like most newer divers, you ran low on gas before you pushed your no-deco limits at all!).
Now assume you are in Bonaire, and want to do a THIRD dive. Your second dive, you did the 50 feet for 30 minutes again. This is where the number in white, the residual nitrogen time, comes in. You go to the top section, top left again, and you look up 50 feet for 30 PLUS the 17 minute residual nitrogen time you got from the back of the card. This gives you 50 feet for 47 minutes, which makes you an "O" diver at the end of that dive.
Spend 30 minutes switching out tanks, and you're ready to go again . . . but reading across the O row to the 30 minute SI tells you you are now an "F" diver. Go to the back of the card, and look up 50 feet, and you're now down to 56 minutes of no-deco time (as opposed to your original 80). So you can see that the nitrogen you haven't offgassed is making your no-deco limits shorter and shorter as the day goes on. The effects are much more marked with longer dives or deeper dives.
At any rate, I hope that helps.
They are not very intuitive, really. But here's a brief description of how it goes. Assume you have done a dive to 50 feet for 30 minutes. You find the column in the upper left section that says 50 feet, and go down to the box that says 31 minutes (because you always round deeper). Go across, and discover you are an "I" diver at the end of that dive.
Now you have a one hour surface interval. Go across the "I" row to the numbers on the right. You will find a box that says 44 - 105. Your 60 minutes SI falls in that range, so you go down that column, and discover you are a "C" diver at the end of your surface time.
Now you go to the back of the card, or the lower of the two cards on the link. Find the column headed by "C", and the row corresponding to the depth of your next planned dive. Let's say you're going back to that wreck at 50 feet . . . your adjusted no-deco time is 63 minutes. This contrasts with the 80 minutes you would have had on the first dive (that you didn't use, because like most newer divers, you ran low on gas before you pushed your no-deco limits at all!).
Now assume you are in Bonaire, and want to do a THIRD dive. Your second dive, you did the 50 feet for 30 minutes again. This is where the number in white, the residual nitrogen time, comes in. You go to the top section, top left again, and you look up 50 feet for 30 PLUS the 17 minute residual nitrogen time you got from the back of the card. This gives you 50 feet for 47 minutes, which makes you an "O" diver at the end of that dive.
Spend 30 minutes switching out tanks, and you're ready to go again . . . but reading across the O row to the 30 minute SI tells you you are now an "F" diver. Go to the back of the card, and look up 50 feet, and you're now down to 56 minutes of no-deco time (as opposed to your original 80). So you can see that the nitrogen you haven't offgassed is making your no-deco limits shorter and shorter as the day goes on. The effects are much more marked with longer dives or deeper dives.
At any rate, I hope that helps.
