What is the best method for inflating a lift bag underwater?

The best method for inflating a lift bag underwater is by using a separate cylinder of air. This method allows for a controlled and safe inflation of the lift bag, ensuring that it expands appropriately to lift the intended object without risk of over-expansion or uncontrolled ascent.

When using a separate cylinder, the diver can regulate the amount of air released into the lift bag, providing a precise means of managing buoyancy. This is especially important in deeper water where the ambient pressure is much greater, as using a regulator with ambient water pressure or relying on ambient water to inflate the bag could lead to buoyancy complications and potential safety hazards.

While inflating with a primary regulator might seem convenient, it can limit control over the rate of inflation, especially under varying depths. Inflating with ambient water pressure does not provide sufficient buoyancy for effective lifting, and using a surface buoy could be impractical in many underwater situations, particularly if immediate lifting is required. Hence, using a separate cylinder is the most effective and safe method for this purpose.