Classed under Det Norske Veritas the tugs will carry the notation; 1A1 R2 Tug, Escort (n,8, n,10), ICE 1A, E0.

At the time of writing the first tug of the pair was carrying out extensive trials following completion by Astilleros Armon SA at their Navia (Asturias) in Spain. Named Ukko the vessel is a rugged azimuthing stern drive tug of 33.5m in length overall, with a 12.80m beam and depth (at main deck) of 6.30m. The hull form includes a long box keel and a forward skeg to increase steering forces when the tug is operating in the indirect mode during escort operations.

Two Wartsila 6R32 main engines produce a total of 4920kW (6685bhp) at 750rev/min to drive a pair of RR Aquamaster type US 3001 fully azimuthing propulsion units with controllable pitch propellers of 2600mm diameter. A bollard pull in excess of 70 tonnes is predicted at 100% maximum continuous rating and dynamic steering forces of up to 100 tonnes in the indirect mode.

The engineroom is equipped with a high level of automation, with an integrated engine alarm and control system manufactured by Lyingo, that meets classification society requirements to be unattended for 24 hours.

A Karmoy single drum towing winch is fitted to the after deck and a combined twin drum towing winch and anchor windlass on the foredeck. The winches and fairleads are winterised with specially designed covers installed on the forward winch to prevent a build up of ice.

Other measures to prevent icing are: a carefully designed superstructure, heated decks and minimum equipment on deck.

An efficient ballasting system allows the vessel's trim to be rapidly adjusted for free running, escort duties or ship-handling.

Fire fighting equipment and a self protection dousing system is fitted and a single remotely operated water/foam monitor has a capacity of approximately 360m 3per hour.

Ukko and its sister ship will have a crew of three accommodated in single cabins.

The living spaces and wheelhouse are heated and air-conditioned.

Five additional crew can be accommodated and facilities include a sauna compartment, shower room, toilet, dressing room, mess room and galley.