Sumburgh Head reaches a significant milestone

Published: 23 October, 2023

Sumburgh Head Lighthouse has reached a significant milestone; on Friday 13th October, the rotation of the Fresnel lens was stopped, the lens was carefully covered, and temporary lights installed. This is all part of the upgrade of Sumburgh Head Lighthouse, which is owned and maintained by Northern Lighthouse Board.

The Fresnel lens has rotated on a 200kg bath of mercury since 1914, which is when Sumburgh Head established its now familiar character of three white flashes every 30 seconds. Over a century later, the mercury is being carefully removed and replaced. In order to do this, the rotating lens has been temporarily stopped and covered. The covering is an essential part of this upgrade; Fresnel lenses comprise a series of prisms that are extremely effective at focusing light and, like a magnifying glass, heat. If an uncovered lens was left in one position for a length of time, the sunlight passing through the lens would be focussed onto one spot and eventually, it would set it alight. Before automation, Lightkeepers had to wind a turning mechanism every 30 minutes to maintain the rotation of the lens. During the daytime, they would lower and close a curtain around the lantern room, to spare them this repetitive task. You can see part of the curtain in the photograph, opposite.

We are genuinely excited to see this work going ahead, as it means the story of Shetland's first Stevenson Lighthouse does not end here, and Sumburgh Head Lighthouse will continue to play an important role in safety at sea.