Knutsen’s newly delivered 123,400 dwt Suezmax shuttle tanker Hilda Knutsen is the fifth vessel in the company’s history to bear this name. But that’s where the similarity with its predecessors begins and ends. Together with its sistership, Torill Knutsen, it will transport oil from the Goliat field 85km (53 miles) off the coast of Finnmark. This has imposed particular design and operational requirements on the vessel, as this is the first oilfield to be developed off northern Norway. The vessels will take oil from a Sevan Marine-designed cylindrical-shaped FPSO, which, in common with these shuttle tankers, has been built for the world’s most northern offshore oil project.
Knutsen technical director Hans Tveitaskog explains that the vessel has been built to Class Notations “Ice Class 1C” and “Winterised Cold” to cope with the harsh conditions in the extreme north. There was especially close cooperation between Knutsen, ENI and Hyundai yard on how to arrange the vessel’s outfitting for the challenging specification, which includes NORSOK requirements for outside work environment, weather tight bow loading area and trunk access to free-fall lifeboat.
The Suezmax shuttle tankers are being chartered by Italian oil major ENI. They have been winterised for Arctic operations with a trunk on the foredeck where all the pipes are placed inside a controlled atmosphere, says Mr Tveitaskog. “Next to providing advantages relating to safety and working environment, this design innovation also means that if an oil leak were to occur, it would be contained rather than spilled.”
Hilda Knutsen is the first vessel in the world to have Knutsen’s KBAL ballast water treatment installed. It is located in a 10 foot container on top of the deck trunk in front of the accommodation. The power supply and control cabinets are placed inside the accommodation. Operating panels are located in the cargo control room and on the bridge and the system has a 3,000m3/h capacity.
The KBAL ballast water treatment is based on a pressure/vacuum reactor where the ballast water rapidly changes from positive pressure to almost absolute vacuum almost instantaneously. It then passes through a UV chamber. No filters or chemicals are involved. According to director of Knutsen Technology, Per Lothe, since the KBAL technology was certified in November, there has been keen interest in the system from wider industry.
Hilda Knutsen is 273.5m long, 46m in breadth and has a design draught of 15m. It has a total cargo tank capacity of 142,200m3 and separate ballast tanks of 52,400m3.
Four retractable Brunvoll azimuth thrusters, each with an output of 2,500kW, provide significant thrust. The two bow mounted thrusters have a dual purpose: when retracted they work as tunnel thrusters making for a very high-powered vessel capable of advanced dynamic positioning operations. The earlier generations of shuttle tankers were designed to weathervane around freely rotating installations (submerged or exposed turrets or buoys) where the aft thrusters could act to keep the vessel’s position and heading as controlled by the DP-system. In this case the buoy is not rotating, so a special DP program and an extended loading hose is used to achieve a 360 degree loading capability. To aid manoeuvrability, there are two Kawasaki skewed CP main propellers and high-lift Becker Schilling rudders. This gives the vessel an enormous sideways thrust capacity, as the main engines generates 2 x 9,960kW x 127 rev/min.
The MAN 6S50ME-C electronic engines also support efficient fuel oil consumption during the DP operation. In good weather conditions (seastate 3.5 and below), the main propellers (main longitudinal thrust) will stay close to zero pitch, with a very low fuel consumption, while the azimuth thrusters will keep the vessel in position. If the weather worsens the main engines will add thrust as required by increasing propeller pitch.
The vessel has been equipped with KVOC (a Knutsen Shipping patented technology) and CVOC to reduce VOC emissions. The cargo tanks are also designed to have a higher tank pressure which reduces the VOC boil-off rate.
The KVOC which is a proven technology in the North Sea will reduce the VOC boil-off during the loading phase. The oil will flow through the bow loading system over the front deck to cargo tank no. 4 before it passes through the KVOC and down into the tanks. The whole idea behind the KVOC is to minimise the sudden pressure drop which occurs when the oil is flowing in a pipe and dropped into an empty cargo tank. We can compare the KVOC principle with tapping beer into a class. If you are holding the class with a sloped angle there will be much less foam compared to when you are holding the class straight.
The CVOC is a system which reduces the VOC emissions during transit. VOC gas which is boiling off will go in a closed loop and re-injected into the crude oil. The CVOC is a simple circulation pump system which re-injects the VOC gas which used to leak out in the atmosphere on older tankers. The vessel will have closed cargo vents in transit because the boil-off (VOC) will be re-injected in the bottom of the cargo tanks where the pressure is highest and re-absorbed in the oil.
A Kongsberg dynamic positioning system has been installed. Because of the winterised conditions a fully electric bow loading station from Pusnes was selected.
The deck area is neatly laid out. Knutsen opted for Pusnes windlasses. The same manufacturer supplied the mooring winches. The steering gear is from Porsgrumm, and the provision and hose-handling cranes have been supplied by TTS Marine.
The pump room is equipped with Hamworthy cargo pumps (4 x 3,000 m3/h). To inert the spaces, Kashiwa plant has been installed.
Knutsen specified a very large Aalborg exhaust gas economiser. Electrical power is backed up by a Nordhom-supplied emergency generator with a 350kW output.
The hull is protected by a KC Ltd impressed current cathodic protection system. Coatings wer supplied by Jotun.
When it comes to crew, Knutsen invests heavily in crew welfare. There is wi-fi for connection to the Internet, which is split into two sections: company business and personal usage. Crew members are not charged for usage.
The new SimSea training centre in Haugesund, Norway, is favoured for DP and bridge management training. SimSea has K-Pos DP training stations that can be linked to other simulators at the site. “All our vessels have Kongsberg bridge, DP and automation systems, so now we will be sending all our officers to SimSea instead of other training facilities,” explains Knutsen OAS Shipping’s managing director, Trygve Seglem. TST