Portland Bill Lighthouse

Portland Bill Lighthouse
Portland Bill Lighthouse
Map
LocationPortland Bill
Isle of Portland
Dorset
England
OS gridSY6773768376
Coordinates50°30′51″N 2°27′23″W / 50.514155°N 2.456383°W / 50.514155; -2.456383
Tower
Constructed1903-05
Constructionsandstone tower
Automated1996
Height41 metres (135 ft)
Shapetapered cylindrical tower with balcony and lantern
Markingswhite tower with a red horizontal band, white lantern
OperatorThe Crown Estate[1]
HeritageGrade II listed building 
Light
First lit1906
Focal height43 metres (141 ft)
Lens1st order catadioptric rotating (original), LED lantern (current)
Intensity635,000 candela 
Range18 nautical miles (33 km; 21 mi)
CharacteristicFl (4) W 20s.

Portland Bill Lighthouse is a functioning lighthouse at Portland Bill, on the Isle of Portland, Dorset, England. The lighthouse and its boundary walls are Grade II Listed.[2]

As Portland Bill's largest and most recent lighthouse, the Trinity House operated Portland Bill Lighthouse is distinctively white and red striped, standing at a height of 41 metres (135 ft). It was completed by 1906 and first shone out on 11 January 1906.[3] The lighthouse guides passing vessels through the hazardous waters surrounding the Bill, while also acting as a waymark for ships navigating the English Channel.[4]

History

Portland Bill Lighthouse at dawn with Trinity House Landmark in the distance

The two original lighthouses, now known as the Old Higher Lighthouse and Old Lower Lighthouse, operated as a pair of leading lights to guide ships between Portland Race and The Shambles sandbank.[1] They were constructed in 1716, both rebuilt in 1869, and decommissioned following the completion of the present lighthouse.[5] At the turn of the 20th-century, Trinity House put forward plans for building a new lighthouse at Bill Point. They acquired the required land in 1903.[6][7]

The builders, Wakeham Bros. of Plymouth, began work on the foundations in October 1903.[8] Chance & Co of Birmingham supplied and fitted the lantern.[9] A pressurised vapour paraffin lamp was used, placed at the centre of a large (first-order) revolving optic; weighing 3.5 tons, this was made up of four asymmetrical catadioptric lens panels and a concave prismatic reflector.[10] The lighthouse was completed in 1905 at a cost of £13,000, and the lamp first lit on 11 January 1906.[5] A red sector light was provided in addition to the main light, shining from a window in the lower part of the tower, to indicate the position of The Shambles.[1] The light was electrified in the mid-1950s.[11]

Interior view of the lamp and lenses in 2017.

In 1940 the lighthouse was provided with an F-type diaphone fog signal, sounding from a window part-way up the tower. Compressed air was provided to six cylindrical storage tanks by a pair of Reavell compressors, all located (together with a standby generator) within the base of the tower.[10] These were connected at a higher level to the sounding tanks, which fed the compressed air to the diaphone itself, mounted behind its trumpet-like emitter which protruded through the window. Admission of air into the diaphone was controlled by a clockwork (later electric) coder, which caused the diaphone to sound a 3.5-second blast every 30 seconds. The 180 Hz note had an audible range of 7 nmi (13 km; 8.1 mi) (which could be doubled under favourable conditions). The diaphone remained in regular use as an aid to navigation until 1995, when it was replaced by a high-frequency electric fog signal (sounding from another window, further down) in readiness for automation.[10]

On 18 March 1996, Portland Bill Lighthouse was demanned, and all monitoring and control transferred to the Trinity House Operations & Planning Centre in Harwich.[12] The original Type F diaphone was decommissioned in 1996, but in 2003 Trinity House restored it to occasional use for the benefit of visitors;[13] (it was sounded regularly for half an hour on Sunday mornings, except when foggy, until 2017).[14]

In the early 21st century the lighthouse used a 1 kW MBI lamp together with the same rotating lens system that had been in use since 1906. (It flashed four times every 20 seconds with an intensity of 635,000 candelas and a range of 25 nautical miles.) The fog signal was used in times of bad weather; it gave a four-second blast every 30 seconds with a range of 2 nautical miles.[4]

In November 2018 Trinity House applied for (and obtained) planning permission to remove the lamp and optic from the lantern room as part of a programme of modernisation.[15] It proposed relocating the lens array to the base of the tower,[16] which led to the removal of the historic diaphone fog-signalling equipment, installed there in 1940 and still in working order, on the basis that this was 'the only available [space] for retaining the historic optic on-site'.[17]

Present day

In 2019-2020 a new non-rotating LED light source was installed in the lantern room[17] and a new omnidirectional fog signal was installed on the exterior lantern gallery (replacing the electric emitter installed in the 1990s).[18] The two LED lanterns (one of which is used, the other kept on standby) have a reduced range of 18 nautical miles (33 km; 21 mi).[19]

Tourist attraction

As Portland's prime attraction, the Portland Bill Lighthouse is open to the public for tours. A visitor centre is housed in the former lighthouse keeper's quarters. The original centre closed in 2013 due to lack of funding,[20] however a new renovated centre opened in 2015.[21] The tours operated at the lighthouse last approximately 45 minutes and visitors are able to climb the 153 steps to the top of the lighthouse.[22]

Gallery

  • The lighthouse and the surrounding ex-quarried area.
    The lighthouse and the surrounding ex-quarried area.
  • Lamps in Portland Bill Lighthouse
    Lamps in Portland Bill Lighthouse
  • Trinity House flag on Portland Bill Lighthouse, Dorset
    Trinity House flag on Portland Bill Lighthouse, Dorset
  • The diaphone foghorn emitter of Portland Bill Lighthouse
    The diaphone foghorn emitter of Portland Bill Lighthouse
  • Fresnel lenses and prismatic mirror
    Fresnel lenses and prismatic mirror

See also

References

  1. ^ a b c Portland Bill Lighthouse Trinity House. Retrieved April 25, 2016
  2. ^ Historic England. "Details from listed building database (1280498)". National Heritage List for England. Retrieved 19 January 2013.
  3. ^ "Portland Bill, Portland, Dorset". Geoffkirby.co.uk. Retrieved 24 November 2012.
  4. ^ a b "Portland Bill Lighthouse". Trinityhouse.co.uk. 18 March 1996. Archived from the original on 27 June 2015. Retrieved 24 November 2012.
  5. ^ a b "Portland – Three Lighthouses Walk". dorsetlife.co.uk. Retrieved 14 June 2015.
  6. ^ "Portland Year Book". ancestry.com. Retrieved 14 June 2015.
  7. ^ Legg, Rodney (1999). Portland Encyclopaedia. Dorset Publishing Company. p. 85. ISBN 978-0948699566.
  8. ^ "Portland Year Book". ancestry.com. Retrieved 14 June 2015.
  9. ^ "Archived copy" (PDF). Archived from the original (PDF) on 29 September 2015. Retrieved 14 June 2015.{{cite web}}: CS1 maint: archived copy as title (link)
  10. ^ a b c Renton, Alan (2001). Lost Sounds: The Story of Coast Fog Signals. Caithness, Scotland: Whittles.
  11. ^ "General Lighthouse Fund". Parliamentary Papers. 20: 16. 1957.
  12. ^ "Portland Bill". trinityhouse.co.uk. Archived from the original on 27 June 2015. Retrieved 14 June 2015.
  13. ^ "Blast from the past (From Bournemouth Echo)". Bournemouthecho.co.uk. 27 August 2003. Retrieved 24 November 2012.
  14. ^ "Portland Bill Lighthouse". The Encyclopaedia of Portland History. Retrieved 22 July 2019.
  15. ^ "Planning – Application Summary". dorsetforyou. Dorset Council. Retrieved 23 March 2019.[permanent dead link]
  16. ^ "The modernisation planned for Portland Bill lighthouse". Dorset Echo. 7 November 2018. Retrieved 12 March 2019.
  17. ^ a b "Heritage Statement / Assessment: Portland Bill Lighthouse Modernisation" (PDF). dorsetforyou. Trinity House. Retrieved 23 March 2019.[permanent dead link]
  18. ^ "Portland Bill Lighthouse Modernisation – DAS & Methodology" (PDF). dorsetforyou. Trinity House. Retrieved 23 March 2019.[permanent dead link]
  19. ^ "Portland Bill Lighthouse visitor centre". Trinity House. Retrieved 21 January 2021.
  20. ^ "Tourism Information Centre shuts at Portland Bill lighthouse". Dorset Echo. 11 December 2013. Retrieved 14 June 2015.
  21. ^ "Portland Bill Lighthouse Visitors Centre". Archived from the original on 22 August 2012. Retrieved 24 November 2012.
  22. ^ "Portland Bill Lighthouse Visitor Centre was just one of many places to visit in Portland Bill Lighthouse Visitor Centre". Resort-guide.co.uk. Archived from the original on 2 May 2014. Retrieved 24 November 2012.

External links

Wikimedia Commons has media related to Portland Bill Lighthouse.
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