Being a new diver I have little experience with the actual planning of a dive. That being said how do you plan your dives in reference to air use, turn pressure, and air remaining. I realize you need to take depth, buoyancy, equipment, comfort level, exertion and other factors into account, but where do you begin and what do suggest when planning your dives?
Great question ... and you are absolutely correct that your air is a resource that should be considered as part of your dive plan.
Think about diving as though you're about to take a drive across a desert ... where the only gas you can rely on is what you're going to be taking with you. What information do you need to know?
- how many "miles" will I be going?
- how many "miles per gallon" does my car get?
- how will conditions affect my "miles per gallon"?
- how much gas do I have in my tank?
Diving's just like that. So the answer to where do you begin is that you first need to figure out your "miles per gallon". This is what's commonly known as your "Surface Air Consumption" ... or SAC rate. The key thing to understand about it is that ... just like the miles per gallon in your car ... it's not a number, it's a range that's determined by a number of variables such as the diving environment and your diving habits.
Once you determine your SAC rate, you can use it to calculate how much gas is appropriate for your dive plan ... basically answering the question, "do I have enough air for the dive I want to do?"
The other significant thing you want to determine is how much gas you need to reserve for emergencies ... keeping in mind that you also want to reserve enough to share with your buddy if for any reason they should encounter a problem.
There's an article on my website called
Understanding Gas Management that explains in detail how this all works. You may find it helpful ...
... Bob (Grateful Diver)