Rowan Companies has exercised an option with Hyundai Heavy Industries (HHI) to build a third GustoMSC P10,000 design ultra-deepwater drillship for $600m.

The vessel cost includes commissioning, project management and spares, but excludes capitalised interest and and is slightly less than the cost of the first two similarly equipped drillships that were previously ordered by the company.

HHI is spending $50m extra on those ships for owner-furnished equipment.

The new drillship is scheduled to be delivered in the fourth quarter of 2014.

The company also has an option to build another ship exercisable in February of 2012 for delivery in the first half of 2015.