Question 1763 Deck Safety

The correct answer is A) BM decreases from loss of water plane and greater volume. As the vessel takes on water and the deck edge at the stern becomes submerged, the waterplane area and moment of inertia of the waterplane (BM) will decrease. This is because the added volume of water on deck increases the vessel's displacement, but the waterplane area remains the same or decreases. Since BM is a function of the waterplane, its value will decrease, which in turn reduces the vessel's transverse stability. The other options are incorrect because: B) There is an effect on transverse stability due to the loss of waterplane; C) KG increases from the added weight of water on deck, but this does not directly affect transverse stability; and D) KB increases, but BM decreases, so GM (the stability index) will actually decrease.