You're right, that doesn't make any sense. The buoyant force is equal to the weight of the fluid displaced. Doubling the volume of your balloons doubles the buo

You're right, that doesn't make any sense. The buoyant force is equal to the weight of the fluid displaced. Doubling the volume of your balloons doubles the buoyant force and therefore doubles the weight you can carry. The relationship is linear, not exponential.