Abstract: The invention relates to a device for protecting a boat hull comprising an inflatable element (100), having a deflated state in which the element is adapted to be positioned both inside or outside of a hull. When located outside the hull, the inflatable element is operatively connected to an inflation/deflation circuit by a conduit (4). A translational control means (7) is provided for causing the inflatable element to be selectively positioned between a position inside the hull or a position outside the hull. When outside the hull, the inflatable element may be inflated or deflated by means of the inflation deflation circuit. A weighted plug is provided at the end of conduit (4) and is shaped to provide sealing engagement with a bushing that provides a through opening in the hull through which the conduit and deflated element pass.