#28736
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From Diver38: The 500 psi is a great idea I say that because as i was doing my check out dive we were in about 45 ft of water and as the tank went from 3000 to 1500 +/- I shot up and out of the water like a torpedo was not a good thing thank god it was only 40 + feet so if anything take on a few more lb then you think to be safe .I also found that I can only use steal tanks do to the rapid change of aluminum tanks .
If you set your weight with the 500 psi in your tank it will not matter what tank you use as long as it the same you dive with. You will not shoot to the surface at the end of the dive if you empty you BCD and/or Drysuit. This is due to the pressure at safety stop depth compressing all the buoyant material you bring down with you from the surface. (swimsuit, BCD, safety sausage, exposure protection) This effect is more pronounced with greater amounts of materials such as thicker wetsuits. This means if you set your buoyancy neutral before you started the dive as I described that at 10’ of depth at the end of your dive you will be slightly negatively buoyant and need to swim to the surface. This check should not be done in shallow water it must be done in water deep enough to allow you to relax your body so your arms and legs are dangling and fins do not hit bottom.
I would agree that if you can’t do a check before boarding to get in the water early and have an instructor or divemaster help you weight. Remember the exhale at the surface it is important to do it completely and give yourself time to sink (without kicking) once you get a few feet under pressure helps you to descend. Do not let them start you heavier than needed. This makes things easier on them but doesn’t factor well for you as a diver. It is best to use the minimum amount of weight necessary to maintain your safety stop depth at the end of the dive. (down to 500 psi) Since this is the minimum you should ever surface with in your tank and once you do surface you will not descend again. 500 psi is a safety to insure proper regulator function and your surface reserve for keeping your BCD inflated.
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