What is the volume of a non-venting lift balloon at 50 feet of seawater (fsw)?

To determine the volume of a non-venting lift balloon at a depth of 50 feet of seawater, it is crucial to understand how pressure underwater affects buoyancy and the volume of gases.

At sea level, atmospheric pressure is about 14.7 psi. As you dive underwater, the pressure increases due to the weight of the water above you. For every 33 feet of seawater, pressure increases by an additional atmosphere (approximately 14.7 psi), leading to about 2 atm of pressure at 50 feet.

The principle of buoyancy outlines that the volume of gas increases inversely with pressure, described by Boyle's Law. When a lift balloon rises or is submerged, the surrounding pressure compresses it, reducing its volume compared to its volume at the surface.

To find the volume at depth, the calculation involves the original volume at surface pressure and the relationship between the volumes changes due to pressure. Assuming an initial volume (for example, if the balloon were designed to accommodate 120 cubic feet at the surface) when adjusted for the increased pressure at 50 fsw, this volume remains consistent with the correct buoyancy principle without any venting mechanism to change volume.

The answer of 120 cubic feet,