Portland Bill Lighthouse
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.
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. It was completed by 1906 and first shone out on 11 January 1906. The lighthouse guides passing vessels through the hazardous waters surrounding the Bill, while also acting as a waymark for ships navigating the English Channel.
History
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. They were constructed in 1716, both rebuilt in 1869, and decommissioned following the completion of the present lighthouse. 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.The builders, Wakeham Bros. of Plymouth, began work on the foundations in October 1903. Chance & Co of Birmingham supplied and fitted the lantern. A pressurised vapour paraffin lamp was used, placed at the centre of a large revolving optic; weighing 3.5 tons, this was made up of four asymmetrical catadioptric lens panels and a concave prismatic reflector. The lighthouse was completed in 1905 at a cost of £13,000, and the lamp first lit on 11 January 1906. 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. The light was electrified in the mid-1950s.
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 within the base of the tower. 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 coder, which caused the diaphone to sound a 3.5-second blast every 30 seconds. The 180 Hz note had an audible range of . The diaphone remained in regular use as an aid to navigation until 1995, when it was replaced by a high-frequency electric fog signal in readiness for automation.
On 18 March 1996, Portland Bill Lighthouse was demanned, and all monitoring and control transferred to the Trinity House Operations & Planning Centre in Harwich. The original Type F diaphone was decommissioned in 1996, but in 2003 Trinity House restored it to occasional use for the benefit of visitors;.
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. 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.
In November 2018 Trinity House applied for planning permission to remove the lamp and optic from the lantern room as part of a programme of modernisation. It proposed relocating the lens array to the base of the tower, 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 for retaining the historic optic on-site'.