Abstract: This invention relates to a sealing device for sealing off an elongated body (1), such as a cable, pipe or umbilical, at its entrance into an aperture (7) of an apparatus, such as an offshore J-tube (8). The sealing device (2) consists of two substantially identical parts or halves (3,4) which are hinged together along an axis (5') substantially parallel to the axis of the elongated body (1), each half comprising a centralizer part (20), a sealing part (21) and tensioning parts (13,16,22) capable of pressing the sealing parts (21) into sealing contact against the elongated body (1), against the inner surface of the J-tube (8) and against the centralizing means (20).