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.

As shipping increased in the 19th century, the need for better orientation along the coasts rose with it. In Europe, the central governments of France, England and Scotland administered the lighting of their coastlines. Denmark, Sweden and the Netherlands also maintained federal organisations for the regulation of seamarks. After the foundation of the German Empire in 1871, a unified system slowly began to emerge in Germany.

In Prussia – the largest coastal nation with the most seamarks – central organisation was of paramount importance. To this end, 100 years ago, on 1 April 1913, the Prussian Seamark Testing Grounds were established in Berlin-Friedrichshagen.

The institute at Müggelsee was overseen by Walter Körte (1855–1914). He drove the development of standardised seamarks and operational benchmarks through his contacts to industry and other neighbouring German states. By the time of the First World War, an effective system of fixed and floating seamarks for daytime and nighttime navigation had evolved. From 1918 onwards, the main focus shifted to collaboration on the international level. After the division of Germany in 1945, the Testing Grounds for West Germany moved to Koblenz, and those for East Germany to Stralsund. In 1990, the two testing centres were merged into one central institute in Koblenz.