Ocean K Rusby is a vessel of 30.8m in length overall with a beam of 11.14m and draft of 3.88m. The hull has a large 'escort skeg' to enhance performance while operating in the indirect towing mode and improve course stability while going astern. An 'ice stop', designed to prevent the hull riding up onto the ice is fitted at the forward end of the skeg.

Two 'ice-diverters' are also installed beneath the stern to stop large pieces of ice from causing damage to the ASD units.

The tug is powered by two Caterpillar 3516 BHD main engines, running at 1,600rev/min, to produce a total of 5,000bhp.

Each main engine is coupled to a Rolls Royce Aquamaster US255 propulsion unit incorporating a 2.4m diameter controllable pitch propeller. Ocean K Rusby is intended to provide escort and shiphandling services and this propulsion configuration gives the tug a bollard pull of 58 tons and a maximum free running speed of 12 knots.

Two electrically powered Ridderinkhof towing winches are fitted, both with a brake holding capacity of 150 tons. A single drum winch for shiphandling and escort towing is installed on the foredeck, to work with a single 120m 'Spectra' towline of 80mm diameter. The second, frequency controlled winch is located aft and is fitted with spooling gear and 762m of 51mm diameter steel wire towline. The after deck is also equipped with a set of 200mm diameter hydraulically operated tow pins and a stern roller for anchor handling.

Electrical power aboard the vessel is generated by two Caterpillar C9 alternators, each delivering 165kVA, Ocean K Rusby is equipped for fire-fighting to FiFi 1 standards. Two Skum remotely controlled water/foam monitors, each with a delivery rate of 1,200m 3/hr of water, are supplied by a single fire pump with a 2,700m 3/hr capacity driven by the port main engine. The usual water spray self protection system required 300m 3/hr and is supplied by the same pump.

Comfortable crew accommodation is provided for a maximum crew of six, in two single and two double cabins.

Irving are currently completing a pair of similar ice class tugs for Danish owners Nordane Shipping.

The first vessel, Stevns Ice Flower, was in the process of running trials in early January. These vessels follow on from the larger ASD tug 'Stevns Arctic' (MJ Towlines - December 2005) completed for the same owner a few months ago.