THE historic foghorn at Sumburgh Lighthouse in Shetland has joined the ranks of Concorde, the Bombe at Bletchley Park and the Jaguar E-Type.
The Sumburgh Head Foghorn, located at the southern tip of the Mainland of Shetland, has been awarded a prestigious Engineering Heritage Award by the Institution of Mechanical Engineers.
For years the eerie sound of the Sumburgh foghorn acted as a warning to shipping to steer clear of the treacherous Shetland coastline.
When it fell silent in 1987, a victim of modern technology, it was mourned by islanders and mariners alike.
Almost 30 years later, the foghorn was painstakingly restored and will once again issue reverberating blasts that can be heard up to 20 miles away.
Work to bring the foghorn back to life was carried out by Brian Johnson, a former lighthouse keeper and engineer with the Northern Lighthouse Board (NLB).
The award was presented at a special ceremony by Past President of the Institution of Mechanical Engineers Bill Edgar to John Mackenzie from the Shetland Amenity Trust who managed the restoration of the Foghorn and other Lighthouse Buildings between 2012 and 2014.
Also in attendance was Brian Johnson.
Previous winners of Engineering Heritage Awards include Alan Turing’s Bombe at Bletchley Park, the E-Type Jaguar and the fastest ever Concorde.
Bill Edgar said: “The Sumburgh Head Foghorn is a magnificent feat of engineering that helped ensure safe passage for countless sailors navigating the North Sea for over 80 years.
“But this award not only honours the great feats of the engineers who created the horn but also the wonderful work of John Mackenzie and the rest of his team at the Shetland Amenity Trust who restored the foghorn to the wonderful condition it is in today.”
John Mackenzie, from the Shetland Amenity Trust, said: “As a chartered civil engineer, I am so pleased to be tasked with receiving this award on behalf of Shetland Amenity Trust and the Sumburgh Head project.
“At the outset of the Sumburgh Head project we had a vision to create something special. Shetland Amenity Trust has received many awards for various projects, this is the first engineering award that the Trust has received, is arguably the most prestigious of all and surpasses our expectations.
“The award is a just reward for all the hard work and great teamwork from the design team, contractors and Trust staff, with special thanks due to our own ‘lighthouse artificer’ Brian Johnson and the Mechanical and Electrical staff at Irons Foulner Consulting Engineers Ltd.”
Although foghorns are now obsolete in modern shipping, they played a very important part in the history of maritime safety.
The sound of the Sumburgh Foghorn is powered by low pressure compressed air, generated by Alley & MacLellan compressors, driven by the three engines in the Engine Room.
The blast is controlled by an air driven clockwork mechanism which operates valves in the correct sequence and at the correct time to spin a siren rotor, housed within the siren chest.
At the right time, a cam operates a valve which causes air to lift a diaphragm valve allowing the full flow of air to pass through the siren – rotating at 1200rpm – thus creating the ‘blast’ noise for the seven second period, then closing the diaphragm valve to stop the sound.
The sound is amplified by the trumpet on top of the tower and in the case of Sumburgh Head, this can be heard as far away as Fair Isle, some 37 miles away.
The foghorn at Sumburgh Head last sounded in 1987, just before the automation of the Lighthouse Tower and the last Keeper left his post in 1991. The light is now operated remotely from the Northern Lighthouse Board offices in Edinburgh.
The Institution of Mechanical Engineers was established in 1847 and has some of the world’s greatest engineers in its history books.
It is one of the fastest growing professional engineering institutions.
Headquartered in London, they have operations around the world and over 113,000 members in more than 140 countries working at the heart of the most important and dynamic industries such as the automotive, rail, aerospace, medical, power and construction industries.
The Engineering Heritage Awards, established in 1984, aim to promote artefacts, sites or landmarks of significant engineering importance – past and present.
Brian Johnson has spent the past few years restoring the mechanics and making the Sumburgh model the only operational foghorn of its type in the UK.
Driven by a diesel Kelvin engine, the foghorn is controlled by an air-driven clockwork mechanism, which operates valves in the correct sequence, and at the correct time.
Johnson is the only lighthouseman now in Shetland with responsibility for keeping all the isles’ lighthouses in running order. Parts of the refurbished foghorn were cannibalised from the Bressay foghorn and donated from the Fraserburgh lighthouse museum.
According to Johnson it is a “very simple and efficient” mechanism. “Obviously being a technician for number of years with the lighthouse board I was able to overhaul the engines,” he said.
“The situation was the engines in the engine room went in in the early 1950s and were not the originals. “So when I went to work on them everything was there. It was all as it was when they stopped, but with the passage of time they needed restoration to get it working.
“It was just what I used to do when I was an engineering with the Lighthouse Board.
“I was delighted to hear her sounding again after such a long time. On a good day it can be heard as far away as Fair Isle.”
Sumburgh lighthouse, built in 1921, was one of dozens in the country designed by Robert Stevenson, grandfather of the writer, Robert Louis Stevenson.
Stevenson snr assessed the area on his first visit and declared it as a suitable site for a lighthouse. The distinctive red foghorn came along some decades later, in 1905, and was built to last a century. Previously, a bell was used to warn mariners of potential danger.
The implementation of the foghorn was a big improvement, as the sound could be heard throughout the Shetland islands in poor visibility.
When shipping began using global positioning satellite technology, the need for foghorns became, like lighthouse keepers, outdated.
Sumburgh was one of the last to be switched off.
When Shetland Amenity Trust approved a £4.5 million refurbishment of the lighthouse, one of the most photographed buildings in the islands and an iconic sight for those flying into the nearby airport, the decision was made to bring the foghorn back to life. Its restoration has just been completed.
Elevated 91 metres above sea level, the light is visible for up to 23 nautical miles and flashes every 30 seconds.
The light is Stevenson’s equiangular refractor, which has 26 reflectors instead of the normal 21.
The light was fully automated in 1991 and ownership of the lighthouse buildings passed into private hands.
In 1994 the area was designated as an RSPB nature reserve and the local office was relocated to Sumburgh Head in 1996.
In 2002 Shetland Amenity Trust purchased the lighthouse buildings and began offering an accommodation service as part of Shetland Lighthouse Holidays.
The light and tower still remain under the ownership of the Northern Lighthouse Board.
In June 2014 the restored buildings and the newly established visitor attraction was opened to the public by the Princess Royal, in her capacity as Patron of the Northern Lighthouse Board.