Semi-submersible tanker with directional ice cutters

摘要

A tanker having a submersible hull has a mast extending above the hull supporting a bridge section. The base of the mast is journaled in the hull for rotation about a vertical axis. The bridge section is rotatably supported on the mast. Drive means rotates the mast relative to the hull and the bridge section such that the hull and bridge section remain aligned while the angular position of the mast is changed. Rotary ice cutters are positioned along one side of the mast and are positioned relative to the surrounding ice by rotation of the mast so as to be aligned with the direction in which the ice encroaches on the mast.