To ensure the possibility of offshore shipping of a liquid medium, primarily oil, from an onshore tank farm into sea-going tankers in the winter time in the ice conditions by ensuring both mooring to an offshore terminal and single-point mooring of a tanker at any time, without depending on the dominating wind and sea condition, in a direction most convenient for it with the possibility of its roundabout turning, with the subsequent servicing of it by transporting a liquid medium into such a tanker the following transformations have been made: a known ice breaker (1) is provided with: a diving station (5) installed on its deck (3), the diving station being provided with a diving trunk (6) made in the hull (2) of the ice-breaker (1), a device for the protection of a flexible hose (8) of an underwater pipeline against ice action, the device being made, according to the first embodiment, in the form of a cylinder (7) provided with guides (13) for moving in a guiding trunk (10) made in the stern side of the hull (2). According to the second embodiment the ice-breaker (1) is provided with a device for the protection of the flexible hose (8) of the underwater pipeline against ice action, the device being made in the form of a pontoon (15) provided with a trunk (16) for servicing the flexible hose (8) and installed in the travel position on the deck (4); a system of single-point mooring and servicing of ships is provided with the ice-breaker (1), which is claimed as an invention, for ensuring offshore shipping of oil, a mooring line and a hose for transporting a liquid medium are made as a single hose-mooring line (28); a method of single-point mooring and servicing of ships, primarily tankers (9) is carried out with the use of the claimed ice-breaker (1) and the hose-mooring line (28).