I'll agree with most of what's written above.
First, the internet isn't a good place to learn something "you're betting your live on". Ask your instructor.
Second: Plan your dive, dive your plan. In many, many years of recreational diving before I switched to technical diving (cave & deep) I never ran over my time nor ran my tank out of gas. It should never happen to you if you pay attention. If you don't pay attention, you shouldn't be diving, at least not that day.
Now having said that, there are a couple of things I'd like to throw out here. One is that all the tables, with the exception of the PADI tables, are based on the US Navy tables but with a safety factor or degree of conservatism incorporated into them. Second is that all decompression theory is just that, theory! They assign a mathematical model that seems to fit empirical data but they don't know what the physical interaction really is. I know divers who popped to the surface omitting over an hour of deco after a 250 foot dive and didn't suffer any ill effects and I know other divers, who stayed well within their tables or computers, but were dehydrated, and ended up in the chamber.
Be safe, stay within the limits of your tables.
First, the internet isn't a good place to learn something "you're betting your live on". Ask your instructor.
Second: Plan your dive, dive your plan. In many, many years of recreational diving before I switched to technical diving (cave & deep) I never ran over my time nor ran my tank out of gas. It should never happen to you if you pay attention. If you don't pay attention, you shouldn't be diving, at least not that day.
Now having said that, there are a couple of things I'd like to throw out here. One is that all the tables, with the exception of the PADI tables, are based on the US Navy tables but with a safety factor or degree of conservatism incorporated into them. Second is that all decompression theory is just that, theory! They assign a mathematical model that seems to fit empirical data but they don't know what the physical interaction really is. I know divers who popped to the surface omitting over an hour of deco after a 250 foot dive and didn't suffer any ill effects and I know other divers, who stayed well within their tables or computers, but were dehydrated, and ended up in the chamber.
Be safe, stay within the limits of your tables.