Question 4759 Deck General

The correct answer is B) a non-watertight opening is at still water level. The downflooding angle is the minimum angle of heel or trim at which a non-watertight opening, such as a vent or hatch, becomes submerged and allows water to enter the vessel. This compromises the vessel's stability and reserve buoyancy. Reaching the downflooding angle is a critical threshold that must be avoided to maintain the integrity of the vessel. The other options are incorrect because they do not directly relate to the definition of the downflooding angle. Option A is about excessive offset, option C is about the load line, and option D is about reserve buoyancy, none of which are the defining criteria for the downflooding angle.