Which statement is NOT part of the three conditions for the free communication effect?

• A. Fully flooded
• B. Open to the sea
• C. Partially flooded
• D. Off centerline

Answer: (A)

The free communication effect happens when water can move freely between compartments and the sea through an opening, so the connected spaces share a common water surface and the system behaves as a single hydrostatic body. For this to occur, three things must be in place: there is a path that connects the spaces to the sea (an opening that allows flow); there is some water in the connected spaces to provide a driving head and a surface for movement (partial flooding, not a dry condition); and nothing blocks that path (the opening isn’t closed by a bulkhead or valve). The statement describing being fully flooded isn’t part of those conditions because complete inundation of the spaces would remove the necessary boundary and the distinct flow path that defines free communication; with full flooding, the scenario isn’t about water moving through an opening to equalize levels in separate compartments.