Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at Hull made from special steels designed for optimum strength at low temperatures low temperatures Air bubbling systems to assist ice Air bubbling systems to assist ice Air bubbling systems to assist ice Air bubbling systems to assist iceAir bubbling systems to assist iceAir bubbling systems to assist iceAir bubbling systems to assist ice Air bubbling systems to assist iceAir bubbling systems to assist ice Air bubbling systems to assist ice Air bubbling systems to assist ice Air bubbling systems to assist ice Air bubbling systems to assist ice-breaking. Air breaking. Air breaking. Air breaking. Air is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from is forced under pressure from 2m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line m or so below the water line where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where ice is met, helping to break it and move out of the way where