The two improved access channels, the 10 km long Torshamnsleden and the 6 km long Bottoleden, are being marked by a total of 34 fully automatic solar powered fairway beacons. To ensure that the flashing red and green lights and GPS will remain operational even during Sweden's dark winter months, Goteborg Hamm asked for a back-up battery system capable of providing sufficient power for 146 continuous days without sunlight. A separate battery was also required to provide 94 days of backup power for the white light. In addition, the batteries had to be suitable for reliable operation in extreme temperature conditions ranging from -25infinity up to +50infinity and require minimal maintenance, with a two year target interval for topping up with water.

The Swedish Maritime Administration, acting as the design adviser and end user for the fairway beacon project, specified Saft's new Sunica. plus low maintenance specialised photovoltaic batteries for the back-up power. The decision was based on the Administration's experience with Saft batteries in its own navigational applications, where a number of battery sets installed well over 20 years previously are still providing reliable service. The Sunica. plus batteries had recently completed long term proving trials with the Administration, during which they had functioned for over four years without topping up.

Two separate 12V battery systems are being installed in a compartment in the main vertical column of the 'L' shaped fairway beacons. Back-up power for the flashing red and green lights and GPS is being supplied by two Sunica. plus 105-5 batteries with a capacity of 105 Ah. Back-up power for the white light is being supplied by five Sunica. plus 370-2 batteries with a capacity of 370 Ah.

Construction of the first fairway beacons commenced in the summer of 2003 and is due for completion in autumn of this year.

MJ Information No: 20011