How do seafarers orient themselves on the sea and off the coasts – at every time of day, in every weather? Besides the natural points of reference – the sun, stars, coastal silhouettes and the Earth's magnetic field – help comes from man-made marks: seamarks. ?These are divided into optical, acoustic and radio-frequency signals – known to us as lighthouses, daymarks, buoys or lightvessels – lighthouses on the waves. ?In the development of seamarks as warning and guidance systems, signal range, unconditional reliability and the cost of operation are important factors.??
The exhibition picks out the highlights in the evolution of optical signals, covering on 70 square metres their development from fire-towers to the oil lamp and gas light, to electrical light sources such as today's wide-spread, bright, energy-saving and long-lasting LEDs. The employment of reflecting mirrors, refractive glass lenses, colours and repeating light signatures demonstrates the ceaseless change in the field of seamarks. Characteristics such as different colours and rhythmic light patterns make it possible to identify the lighthouse emitting the signal, and hence improve guidance.?Numerous original objects such as glass optics and measuring equipment, as well as archive material and photographs trace the development of a unified German system of seamark administration. ?The exhibits were acquired by the Museum of Technology in 2009 from the Transport Technology Unit of the Federal Waterways and Shipping Administration in Koblenz.