The invention relates to a motor boat comprising a bearing structure (1) and at least one foil (2) which is defined by a hydrofoil and its support (4), which is positioned under said structure and slideably mounted with respect to the latter; characterized in that the foil (2) is also mounted in such a way as to adopt at least two fixed positions, namely a position referred to as the active position in which the foil (2) is lowered and a position referred to as the passive position in which the foil (2) coincides with the bearing structure (1) or is fully retracted into the latter.