The 25,080dwt product tanker Purha is the first in a quartet of Chinese-built vessels for the Finnish energy group Fortum
Fortum Shipping currently operates a fleet of some 30 tankers, including both its own and time-chartered vessels. Several vessels are also owned by financing companies and on bareboat charter to Fortum Shipping. The four new ships form part of an extensive fleet-renewal programme which aims for the highest standards of safety and the best possible performance in ice.
This renewal programme sees a number of older vessels being replaced by newbuildings. Purha, first in a series of four 25,080dwt product carriers from Jinling Shipyard in China, is part of this investment in new tonnage, amounting to ten vessels in total.
Purha's sister vessel Jurmo and two others are all due for delivery in 2004. They have been designed mainly for export shipments of oil products in the Baltic Sea and North Sea from Fortum's refineries in Porvoo and Naantali. To ensure year-round operation in the severe ice conditions in the Gulf of Bothnia and the Gulf of Finland, the vessels are being built to the highest Finnish/Swedish ice class 1A Super standards.
Double hulls throughout
Purha is a double-hull tanker, constructed for carrying IMO class II chemicals and oil products. The double hull also covers all of the fuel and lubrication oil tanks on board.
The vessel has ten segregations. For carrying cargo, there are seven pairs of fully epoxy-coated tanks, separated by a bulkhead in the centre line. The cargo tanks have a total volume of 28,283cbm at 100 percent filling. The tanks in the outer hull are for ballast water only.
A full cargo can be discharged in about eleven hours. The electric, variable-speed deep-well cargo pumps come from Hamworthy KSE Svanehoj. The capacities are 300 cbm/h for the tank pairs 1 and 2 and 445 cbm/h for the larger tank pairs 3, 4, 5 and 7. Both cargo and slop tanks have stainless-steel double-loop heating coils: primary heating is by steam and secondary heating by a mixture of water and glycol.
The inert gas generator is of Air Products type MPG-900, with a capacity of 3,250 cbm/h. All cargo and slop tanks are included in the inert gas system, while the ballast tank and cargo piping may be inerted using removable connections.
A nitrogen system is provided for cargo stripping and purging of cargo piping, and for creating a layer of nitrogen on top of the cargo.
Medium-speed engine
Fortum has chosen a machinery configuration with a medium-speed engine coupled to the shaft via reduction gear. As the service profile of these vessels consists primarily of short sea legs, the medium-speed engine is considered to give better performance overall than a slow-speed engine. From experience, Fortum Shipping also prefers medium-speed engines for operation in ice during winter.
The main engine is of Waertsilae type 9L46C, with an output of 9,450 kW at 500 rev/min. Waertsilae's water injection system and low-NOx combustion system significantly reduce environmentally harmful emissions.
The Kamewa CP propeller is a four-bladed stainless-steel design, with a diameter of 5,800 mm. The speed of rotation is 115 rev/min. The 1,200 kW bow thruster is also from Kamewa. The ship has three Waertsilae auxiliary engines of type 6L20, each developing 1,020 kW at 900 rev/min and coupled to a 1,200 kVA generator. At sea, electric power is supplied by a 1,875 kVA shaft generator. Both it and the diesel-driven generators have been manufactured by van Kaick.
Fuel consumption of the main engine is 28t HFO per day at a normal service speed of 15 knots. On sea trials, Purha reached a speed of 16.4 knots at design draught.
Ergonomic bridge design
Fortum has introduced a standardised bridge layout on its new vessels. One of the basic qualities is user-friendliness, with ergonomic considerations at the forefront. Hence the bridge environment is familiar to deck officers transferred from one Fortum vessel to another.
The bridge is classed by DNV for one-man operation. The integrated bridge control system includes a monitor for the electronic chart and information system (ECDIS), and a radar screen at each conning place. Furuna-Navintra is the turnkey supplier of the bridge and its navigation system.
This is an edited version of an article which first appeared in the Scandinavian Shipping Gazette Yearbook 2003/2004