Once again displaying their diversity for use in the domestic petroleum industry, one of Crowley’s four ocean class tugs, Ocean Sky, recently provided back-up station-keeping and holdback services during a routine blackout test of ultra-deepwater, semisubmersible oil rig Noble Jim Day in U.S. Gulf of Mexico. This Shell-leased, Noble-owned rig is currently operating in about 9,600 feet of water in the 508 section of Walker Ridge as part of the Stones Prospect. As part of routine blackout testing…