The rig owner said last week that it recently decided to replace the cranes because of "mechanical and reliability issues with the original deck cranes".
"We ran into some concerns about them," said an Ensco spokesman.
He was unsure at the time if the Ensco 8500 would need to go to a yard and, if so, which one.
The crane replacement will force the rig to start operations in the US Gulf in June, two months later than originally anticipated.
The
