The coast guard in Alaska is preparing for a 54-metre ghost ship drifting aimlessly in the Pacific Ocean to float into U.S. waters.

The unmanned fishing vessel is at the forefront of tons of debris floating across the Pacific from last year's massive tsunami in Japan.

U.S. Coast Guard Petty Officer David Mosley says the coast guard dropped a data marker on the ship on Saturday so they have a constant, real-time, position on the vessel.

A U.S. coast guard cutter will also head out this week to assess the safety of the vessel, the potential hazards on board and to determine if it should be sunk or towed in for salvage.

The ship is about 150 kilometres west of the northern most tip of Haida Gwaii, or the Queen Charlotte Islands, off the B.C. coast.

Mosley says it appears to be drifting north toward Alaska's waters.

Mosley says the Dixon Entrance, that marks the divide between Canada and the United States, is heavily travelled with cargo, fuel and cruise ships and the drifting boat could create a serious hazard.