In the 152-page report(pdf), which detailed operator Shell's failings in carrying out proper risk assessment for the rig move in the face of harsh winter weather conditions, the Coast Guard did not let the Louisiana-based contractor off the hook.

"This investigation has determined that there is sufficient evidence that a violation of law or regulation may have occurred on the part of Edison Chouest Offshore in that they failed to report the numerous marine casualties and safety related vessel issues," the report said.

"As