Fog Horn
29.07.2026
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| Built in 1905, the Sumburgh Head foghorn is a compressed-air diaphragm siren. Three diesel engines drive air compressors that charge storage receivers to about 25 psi (1.7 bar), while a pneumatic clockwork mechanism automatically releases a 7-second blast every 90 seconds. The siren rotor spins at approximately 1,200 rpm, and the large trumpet projects the sound as far as Fair Isle, 37 miles (60 km) away in favourable conditions. Decommissioned in 1987 and restored in 2015, it is believed to be the last operational diaphragm-siren foghorn of its type in Scotland, and possibly in the world |