In dewatering, which action should be performed first to prevent the spread of flooding?

• A. Isolate the space.
• B. Vent the space.
• C. Seal all hatches.
• D. Shift ballast.

Answer: (A)

Isolating the space is the first move because it immediately creates a barrier that stops flood water from moving into other compartments. By quickly closing and securing watertight doors, hatches, vents, and other openings to adjacent spaces, you prevent the water from spreading as you begin dewatering. Venting the space would undermine that containment by allowing air and potentially water to move between compartments, which can propagate the flood. Shifting ballast doesn’t directly stop the flow of water between spaces, and sealing hatches is part of isolation, but the essential first action is to establish the watertight boundary around the affected area.