Abstract: A vessel with a ballast system including a plurality of ballast tanks provided with means for feeding water into the tanks and expelling water therefrom and an air bubbling system including underwater openings and means for blowing air through said openings into the water surrounding said vessel. The ballast system and the air bubbling system include a common tube system being alternatively connectable to the ballast tanks, for operating the filling and emptying of the tanks, and to the air bubbling system for conducting air to the underwater openings as described in U.S. Pat. No. 3,580,204.

Abstract: A method for protecting stationary constructions, located in water and surrounded by water, against strain caused by a moving ice field in said water. A protective structure is arranged around said stationary construction. Said protective structure has a cross-section considerably greater than the cross-section of said stationary construction and it comprises, at the water surface level and below this level, an outer surface which slopes downwards in a direction against the stationary construction to form an ice breaking surface bending downwards ice, which move against said protective structure.

Abstract: A vessel with a ballast system including a plurality of ballast tanks provided with pumps for feeding water into the tanks and expelling water therefrom and an air bubbling system including underwater openings and compressors for blowing air through said openings into the water surrounding said vessel. The ballast system and the air bubbling system include a common tube system being alternatively connectable to the ballast tanks, for operating the filling and emptying of the tanks, and to the air bubbling system for conducting air to the underwater openings as described in U.S. Pat. No. 3,580,204.