The 29 meter long tug Nathan E. Stewart along with its 287 foot tanker-barge became disabled after the starboard engine failed while off Cape Fairweather, Alaska.   The tug has able to maintain power but not enough to keep the vessel from drifting.   The barge is loaded with 2,500,000 gallons of diesel fuel.  The Coast Guard has dispatched cutters to the scene.   A commercial tug from Hawk Inlet has also been dispatched to the scene.  No reports of injuries, damage or pollution being released.   Reports state the tug and barge are off shore and there are no concerns the vessel may run aground.