Lookchart67
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How to improved the situation. Can even perform a 5 m safety stop successfully.?
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Maybe I read your message in a different way than intended. But the material of the tank doesn't change the buoyancy shift between the beginning and the end of the dive.Are you diving an Aluminum 80 cylinder? These are known to be positively buoyant as the air in them is depleted. If this is the cylinder you are using then you might need to compensate by either diving with more lead balast so you are properly weighted towards the end of your dive
Maybe I read your message in a different way than intended. But the material of the tank doesn't change the buoyancy shift between the beginning and the end of the dive.
Right. But the buoyancy SHIFT is dependent on the weight of the air that is depleted during a dive.An AL80 cylinder will be negatively buoyant at the beginning of the dive when full, and it will be positively buoyant towards the end of the dive when it is empy-ish.
For example, a Catalina S80 (AL80):
Buoyancy full (207 bar)= -1.6lbs
Buyancy @ 500psi (@ 34 Bar) = +2.8lbs
Buoyancy empty = +4.1lbs
View attachment 789864
-Z
I believe his point was that aluminum tanks will be buoyant when near empty at the end of the dive. Basically, you have a cork on your back and the lead you carry should account for that transition.Right. But the buoyancy SHIFT is dependent on the weight of the air that is depleted during a dive.