Question 4639 Deck General

The correct answer is B) natural rolling period. When a drilling barge inclines, the movement of liquid in the tank causes the natural rolling period of the vessel to increase. This is because the shifting of the liquid alters the vessel's metacentric height (GM), which is a measure of the vessel's initial stability. As the GM decreases, the natural rolling period increases, making the vessel more susceptible to rolling motions. The other options are incorrect because: A) the height of the uncorrected KG (vertical center of gravity) is not directly affected by the liquid movement, C) the metacentric height may decrease due to the liquid movement, and D) the righting arm is a measure of the vessel's ability to right itself, which is not the primary concern in this situation.