The 91 meter long, 3500 dwt tanker Cliffwater became disabled in the North Sea near Great Yarmouth.  The Cliffwater loaded with a cargo of benzene had suffered engine failure and gone adrift.    Tugs were dispatched and took the Cliffwater under tow.    The vessels proceeded to Rotterdam and arrived a short time later.  No reports of injuries, damage or pollution released.   The Cliffwater was en route from Immingham to Le Havre.