The giant Blackford Dolphin oil rig, initially set for a whistle-stop 60-day renovation project in Belfast, will now remain in the city's docks until June, the Belfast Telegraph can reveal.
The 360ft structure sailed into the Harland & Wolff shipyard in early December from Brazil for a refit.
In March, following the discovery of the need for additional "emergent" work, the rig's owners Dolphin Drilling told the Norwegian Stock Exchange that the work would continue until April.
However, that deadline has now been extended again for almost another two months – and the race is on to finish the work.
The city's famous gantry cranes Samson and Goliath, which have been temporarily moved to make room for the massive rig, have to be rolled back into the yard to assist in the delivery of large wind turbine parts currently being made at the shipyard's assembly hall for another client.
Harland & Wolff says that the initial work schedule provided to the company was finished within the specified time frame and that a certificate of completion has been issued.
David McVeigh, head of sales and marketing at H&W, said: "The need for this additional vital work would never have been identified until the rig came into the dock.
"The workers at Harland & Wolff completed the scheduled refurbishment work within the specified time frame and this is now purely structural repair work being carried out.
"We do face a race against time to have everything finished for June as we require the gantry cranes to help make deliveries at around the same time as the work on the rig is due to be completed.
"We are currently looking at alternative options if for some reason the work needs to continue for a longer period."
But the further delay will bring good cheer to the 600 skilled tradesmen who have been working around the clock on the Blackford Dolphin, and the shops, restaurants and hotels who have been serving them.
Aberdeen-based Dolphin Drilling Ltd awarded the contract – worth tens of millions of pounds – to Harland & Wolff for the dry-docking of the rig in 2013.
Around 1.2m tonnes of water had to removed from the longest dock in the world to accommodate the rig, which has a rated water depth of 7,000ft and a drilling depth of 30,000 ft.