Can someone give me a formula or give an approximate approach to calculating the time it would take for an object to be raised up (due to buoyancy) from a certain depth of water? For instance, take a ship (say it weighs 300,000kg and it's a rectangular shape with surface area of 100m square (10m by 10m). If i attach enough air ballons around the ship , what would be the variables and formula to use to get an approximate time it would take to raise the ship to the surface from say 100meters of water (sea water). I assume that the the surface area of the ballons might be a factor too but let's just leave those out (say i put the underneath the ship). I am not concerned about the acceleration at the end destroying the ship near the surface. I am fearful of this solution turning into a series of calculus equations b/c of the rate of change of pressure as the ship goes higher.