There are also four further RL-355s located onshore, two red and two green, to mark the port and starboard limits of the channel.

The three white lanterns of the leading light arrangement have a maximum range of 22Nm and are linked by radio, but not synchronised as each flashes a different character. Two of the three white lanterns have a radio receiver with external antenna and communicate by line-of-sight with the antenna on the control station, which is located adjacent to the central lantern. The front lantern of the three is installed in a special steel housing for protection against any risk of vandalism.

The system incorporates a sun switch in the central control unit that commands all three lanterns to dim at nightfall and return to full brilliance after dawn. A parallel circuit allows this ‘auto’ function to be overridden when conditions such as night fog make it necessary to increase the brilliance of the range lanterns. The override function is accessed by sending a text message from the operator’s mobile phone activating the lights for a pre-set period.

Tideland’s RL-355 is a high power, high efficiency lantern that was originally designed in collaboration with the US Coastguard. Its TF-3B MicroPower Omnibus II flasher/lampchanger incorporates a timer circuit card to permit input voltages up to 36V and provide up to 256 user-selectable flash codes.

The port of Esbjerg on the coast of Jutland is regarded as Denmark’s western gateway. The approach is via a narrow channel between the peninsula of Skallingen and the island of Fanø, after which vessels turn to starboard to reach the port itself, which lies to the south east, in the lee of the island.

Esbjerg’s fishing and general traffic harbours offer a total of 10km of quays, which handled over 4m tons of goods in 2005. It is a centre for the offshore oil and gas industry, general cargo, bulk, ro-ro, ferries and passenger liners.