Abstract: A floodwater barrier for protecting the shore side of a shoreline from flooding includes at least one self-actuating floodwater barrier unit for installation between a pair of walls transverse to a shoreline. The unit includes a flexible resilient panel, a plurality of rigid members connected to the panel, at least one watertight chamber of size and arrangement to give the unit water buoyancy, hinged to be rotatable upward about a horizontal axis longitudinal to the shoreline under the influence of buoyancy and hydrostatic pressure from a rise of the body of water acting on the unit, and further includes flexible tension members positioned to act on the floodwater barrier unit to limit upward rotation of the unit to a predetermined extent.

Abstract: A buoyant flood guard barrier panel passively buoyantly rotationally pivotable upward from horizontal about a first horizontal axis overlays a subframe unattached to the panel. A secondary mechanism for raising the panel has one or more lift arms below the panel transverse to the first axis are rotationally mounted on a second horizontal axis parallel to, below and forward of the first axis. One or more powered drivers act on one or more driven member units each attached to a lift arm rearward of and lower than the second axis to pivot the lift arm on the second axis, rotating the arm upwardly under the panel to rotationally raise the panel. The powered driver may be a winch or a hydraulic actuator.

Abstract: A buoyant flood guard barrier panel passively buoyantly rotationally pivotable upward from horizontal about a first horizontal axis overlays a subframe unattached to the panel. A secondary mechanism for raising the panel has one or more lift arms below the panel transverse to the first axis are rotationally mounted on a second horizontal axis parallel to, below and forward of the first axis. One or more powered drivers act on one or more driven member units each attached to a lift arm rearward of and lower than the second axis to pivot the lift arm on the second axis, rotating the arm upwardly under the panel to rotationally raise the panel. The powered driver may be a winch or a hydraulic actuator.

Abstract: A plurality of flood prevention units are vertically stacked one over another inside a frame mounted over ventilation opening on a wall. Each unit includes a buoyant gate pivotally mounted by one or more pivotation members about a horizontal axis transverse to sidewalls of the frame for pivotation of the gate on rise of water buoyantly lifting the gate rotationally upwardly between said sidewalls for engagement with an upper deck horizontally connecting the sidewalls. A limiter limits the extent of self-actuation rotation of the gate. The gates are open during non- flooding conditions, allowing ventilation through the building opening, and sequentially close from lowest to highest on rise of water activating each gate in order, allowing ventilation to continue until the highest gate is closed.

Abstract: A buoyant flood guard barrier panel passively buoyantly rotationally pivotable upward from horizontal about a first horizontal axis overlays a subframe unattached to the panel. A secondary mechanism for raising the panel has one or more lift arms below the panel transverse to the first axis are rotationally mounted on a second horizontal axis parallel to, below and forward of the first axis. One or more powered drivers act on one or more driven member units each attached to a lift arm rearward of and lower than the second axis to pivot the lift arm on the second axis, rotating the arm upwardly under the panel to rotationally raise the panel. The powered driver may be a winch or a hydraulic actuator.

Abstract: A floodwater barrier for protecting the shore side of a shoreline from flooding includes at least one self-actuating floodwater barrier unit for installation between a pair of walls transverse to a shoreline. The unit includes a flexible resilient panel, a plurality of rigid members connected to the panel, at least one watertight chamber of size and arrangement to give the unit water buoyancy, hinged to be rotatable upward about a horizontal axis longitudinal to the shoreline under the influence of buoyancy and hydrostatic pressure from a rise of the body of water acting on the unit, and further includes flexible tension members positioned to act on the floodwater barrier unit to limit upward rotation of the unit to a predetermined extent.

Abstract: A horizontally pivoted structurally rigid buoyant flood gate, in a housing for the gate arranged in front of an opening to a construction, is pivotally floated out of the housing by rising water entering a portal to the housing, and rotates buoyantly upward toward the opening, rising between two side walls longitudinal to the opening and separated from each other by little more than the side-to-side distance of the gate, allowing little water through any gap separating the gate from the side walls, which preferably is sealed by a compression seal, the hydrostatic pressure of water dammed behind the rising gate urging completed closure of the gate through at least the upper half of the closing arc, pressing the gate sealingly against the jambs.