How can I obtain the flow coefficient of the crack of the box?

Someone drops a box with a crack into the sea. Soon water starts to leak into the box. The box does not sink to the bottom instantly, because the box is not filled up with water and there is an air cushion inside the box. When pulling upwards with a force F through a strand of rope tied to the top of the box, the box rises a little. However, the F is not strong enough to lift the box till the crack is above the sea level. Slowly reduces the force F, the box returns to the original place. Suppose the speed is kept constant for the upward and downward movements.