Virtually identical, the vessels will have azimuthing stern drive propulsion systems, a predicted bollard pull of 124 tonnes and maximum speed of 14.8 knots.

Two main engines developing a total of over 10,000bhp will provide power to the propulsion system comprising two fully azimuthing stern drive-units incorporating controllable pitch propellers. A maximum of 588m 3of fuel can be carried giving the vessels a range of 5230 miles. Manoeuvrability will be enhanced by a transverse bow-thruster and dynamic positioning will be installed to 'DYNAPOS AM' standards.

The latter will enable each vessel to maintain station within precise limits, move sideways under complete control, and turn through 360º about its own axis in just 30 seconds.

Each vessel will be fitted with a massive amount of equipment for salvage, towing, fire fighting and pollution control duties. In order to undertake anti-pollution and clean-up operations after major incidents at sea the tugs will be fitted with side sweep and portable skimmers, booms, pumps and dedicated tanks to accommodate 298m 3of recovered oil residue. Fire fighting equipment to FiFi 1 standards will also be installed, incorporating high level monitors and a self-protection spray system.

The first of the tugs, to be based in Galicia, will be delivered in the first half of 2005 with the second due to be handed over five months later.