Major refit for ‘Aranda’
The Finnish research ship ‘Aranda’ is undergoing a major refit that will see the vessel both lengthened and fitted with an upgraded propulsion system.
Owned by SYKE which is the Finnish centre for environmental research, Aranda was built in 1989 by the Wartsila Shipyard in Helsinki and has carried out extensive oceanographic research work in both the Baltic waters as well as in international waters. It is anticipated that the refit work will adapt the vessel for many more years of operations as well as improving the green credentials of the vessel.
As a major part of the refit a new 7-metre-long section is being fitted into the hull and the stern will also be extended. The cut for the centre section has been made close to the aft end of the existing superstructure and the combination will add 50sq.m to the aft working deck as well as providing space for additional superstructure facilities. By making the cut in this position it means that the existing stern gear and the location of the drive motors to the single propeller can be retained thus simplifying the operation.
Aranda was built with a diesel electric propulsion system and this will be retained. The two main diesel engines are both from Wartsila, one a Vasa unit producing 1300kW and the other, also a Vasa unit, which produces 1700kW. These provide the power for the two 1500 kW Bakker electric propulsion motors that drive the single propeller. Three 280 kW Cummins powered Stromberg generators provide the auxiliary power and domestic load and as part of the refit work all of the machinery will be converted to operate on bio-diesel to improve the green credentials of the vessel. The maximum continuous power output is 2800 kW with a possible peak power of 3800 kW.
The green credentials will also be improved by the addition of a lithium ion battery pack. Initially this will have a capacity of 200kWh with a maximum output of 1000kW but there will be the capability to increase the batteries to 2000 kWh to allow silent battery operation for more extended periods. This will help with research work when the vessel is required to enter sensitive areas for operations. It will also allow the vessel to operate with no diesel engines running to further improve the very low noise level capability of the vessel. The larger battery pack will help to extend this electric power only operating time considerably and as a further expansion of the green credentials Aranda will also have a fuel cell system installed. This will provide 160kW of power as well as the same amount of heating and will be largely an addition to the domestic supply of the vessel.
An alternative means of propulsion will be added during the refit. This comprises a Schottel Pump Jet unit of type SPJ 132 RD which fits flush with the hull bottom so that is should not compromise the ice-breaking capability of the vessel. The Pump Jet will be flexibly mounted with a rubber cushion so that by using this unit as the means of propulsion there will be minimal vibration and noise transmitted which can be important for marine research work.
The Pump Jet will be installed into the hull bottom in the forward part of the hull. This unit can rotate through 360° to direct the thrust in any desired direction so that the vessel will retain its dynamic positioning capability when using the Pump Jet alone. It will be powered by a 400kW electric motor which should give the vessel a forward speed of 3 knots when operating with the Pump Jet alone. A new 3mW generator is being installed to supply power to this propulsion unit as well as to other equipment in the new hull section. When being used for dynamic positioning the Pump Jet will be capable of maintaining a position to within ½ metre and this additional propulsion system also provides a ‘get you home’ capability.
The efficiency of the 60-metre-long Aranda will be improved by the addition of the 7-metre-long extension. This will create a more efficient hull shape with reduced resistance which will help to compensate for the additional weight. It is anticipated that the current 10.5 knot cruising speed and maximum speed of 13 knots will be retained or possibly increased. The vessel has a full dynamic positioning capability with bow and stern thrusters and manoeuvrability is aided by having a Schiller high lift rudder.
The remainder of the space in the new section of the hull will be used to provide additional laboratory and research facilities. The added length will also create additional working deck space as Aranda is equipped for a wide variety of sampling methods both of the water column as well as the seabed and the aft extension will house a compartment for towed vehicles.
The refit work is being carried out at the Rauma Marine Constructions yard at Rauma and is scheduled for completion in the spring of 2018. It is anticipated that this upgrading and extension work will extend the vessel’s useful life up till 2030. The vessel is one of very few research vessels that have the capability to operate in ice conditions and it is anticipated that she will work in both the arctic as well as in Finnish home waters of the Gulf of Bosnia and the Baltic Sea. She is used by several Finnish research institutes for a wide variety of environmental and marine research work and has been chartered to the Swedish equivalents as well.
By Dag Pike
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