Boarderguy
Chief Narctopus Wrangler
That's how you know they're around. You see a silt cloud when solo at 100' lolSomeone needs to teach that guy to frog kick to stop stirring up the silt!
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
That's how you know they're around. You see a silt cloud when solo at 100' lolSomeone needs to teach that guy to frog kick to stop stirring up the silt!
the way they contort their fat bodies gives me a real complex being such an inflexible fat a$$.That's how you know they're around. You see a silt cloud when solo at 100' lol
In a CESA, the student should begin the ascent neutrally buoyant, as would happen on a real dive. During the ascent, the BCD will expand, and the student is taught to dump air a little at a time as that happens so that the ascent remains under control.
A diver's buoyancy is based on the weight and volume of the entire package of the diver. If the weight of the diver, tank, and gear is equal to the weight of the same volume of water, then the diver is neutrally buoyant. If a diver is neutrally buoyant at the time he or she goes out of air, then at that moment, the diver, the gear, the weights, the now empty tank, and the amount of air in the BCD equals the weight of that volume of water.Unless of course they have little to no air in their BCD because it's the end of the dive and it's their empty Al80 that pulls them up.
In addition to what I wrote above....
The navies of the world have used buoyant ascents for submarine escapes since the early 1950s. A Google search will find navy films showing it. The older ones are better because the escape is done with nothing but a very primitive BCD rather than the special suits used now. The students are taught to exhale fully before starting the ascent, and then continue to ascend the entire way up. This has been done from 300 feet.
I wrote to PADI about this, too. They told me that the dividing line between CESA and buoyant ascent was really your judgment.
Really? The scuba tank displacing the same amount of water but having less weight doesn't affect buoyancy?A diver's buoyancy is based on the weight and volume of the entire package of the diver. If the weight of the diver, tank, and gear is equal to the weight of the same volume of water, then the diver is neutrally buoyant. If a diver is neutrally buoyant at the time he or she goes out of air, then at that moment, the diver, the gear, the weights, the now empty tank, and the amount of air in the BCD equals the weight of that volume of water.
If the neutrally diver begins to ascend at that point, the only change in buoyancy will be caused by the increasing volume of the air in the BCD and the increasing volume of bubbles in the wetsuit or drysuit. The empty scuba tank will not have any change in buoyancy during that ascent, and will have no effect on buoyancy.
There is a fixed, linear decrease in the weight of the tank as the pressure is steadily declining during every dive. Initiating an ascent when the tank pressure is low, will not cause a buoyancy change in the tank.Really? The scuba tank displacing the same amount of water but having less weight doesn't affect buoyancy?
Ah yes, I missed the context of AFTER beginning ascent. Certainly it doesn't change with depth.There is a fixed, linear decrease in the weight of the tank as the pressure is steadily declining during every dive. Initiating an ascent when the tank pressure is low, will not cause a buoyancy change in the tank.
I also know that running out of air does not just happen by accident. It should never happen.