Fastnet Rock

Fastnet Lighthouse is a 54m high lighthouse situated on the remote Fastnet Rock in the Atlantic Ocean. It is the most southerly point of Ireland and lies southwest of Cape Clear Island and from County Cork on the Irish mainland. The current lighthouse is the second to be built on the rock and is the tallest in Ireland.

First lighthouse

Construction of the first lighthouse began in 1853, and it first produced a light on 1 January 1854. The lighthouse replaced an early one built on Cape Clear Island in 1818, partly motivated by the loss of an American sailing packet, '' Stephen Whitney'', in thick fog during November 1847 on nearby West Calf Island causing the death of 92 of her 110 passengers and crew. The new lighthouse was constructed of cast iron with an inner lining of brick and was designed by George Halpin. Costing £17,390, the tower was tall with a high lantern structure on top, giving a total height of around . It had an oil-burning lamp of 38 kilocandelas; in contrast, modern lighthouses typically produce 1,300 kilocandelas. In 1883 an explosive fog signal was installed, which electrically detonated a small charge of guncotton every five minutes.

The tower proved to be too weak since gales shook it to the point that crockery was sometimes thrown off tables, and a 60 imperial gallon (273 L) cask of water lashed to the gallery above high water was washed away. Various steps were taken to strengthen the tower, including fitting a casing around the bottom section up to the second floor and filling it with stone, and the surrounding rock smoothed over. In 1865 the lower floors were filled in with solid material.

Second lighthouse

In 1891 the Commissioners of Irish Lights had resolved that the light was not sufficiently powerful, particularly for the first landfall for many ships crossing the Atlantic. The replacement was constructed of stone, cast iron now being considered unsatisfactory – the whole of the nearby Calf tower above its strengthening casing had been carried away during a gale on 27 November 1881, although without loss of life. On the same day, the sea had broken the glass of the Fastnet Rock lantern.

The new lighthouse was designed by William Douglass and built under the supervision of James Kavanagh. Construction started in 1897 with the levelling of the site, and the first of 2,047 Cornish granite dovetailed blocks was laid in June 1899. As well as these blocks, weighing 4,300 tons in total and with a volume of , a further of granite was used to fill the inside of the tower up to the level of the entrance floor above high-water mark. A small steamship, the ''Ierne'', was specially constructed for carrying the blocks out to the island, and Kavanagh personally set every stone, which weighed between 1¾ and 3 tons. The new lighthouse entered service on 27 June 1904 having cost nearly £90,000.

The masonry tower is high, but the focal point of the light is above high-water mark. The base of the lighthouse is in diameter with the first course of stone below the high-water mark, and the first ten of the 89 courses built into the rock. The first floor of the original tower remains, on the highest part of the rock, having been left when it was demolished and converted into an oil store.

The fog signal was changed to one report every three minutes in 1934 and from 1965 accompanied by a brilliant flash when operated during darkness. The original vaporised paraffin light was replaced with an electric one on 10 May 1969. At the end of March 1989, the lighthouse was converted to automatic operation. It is monitored and controlled using a UHF telemetry link to Mizen Head Lighthouse in County Cork, and onwards by landline to the control centre at Dún Laoghaire.

It produces a 0.14-second white flash every five seconds, with a nominal range of and a power of 2,500 kilocandelas. Since April 1978 in addition to being operated during darkness, the light is also used during poor visibility. In 1974 the explosive fog signal was replaced with an electric foghorn producing four blasts every minute at 300 hertz with a nominal range of . Following a review of navigational aids, the fog signal was permanently shut down on 11 January 2011. The Racon – radar transponder beacon – has been a morse G on the radar display since its installation in 1994.

In 1985, the lighthouse was struck by a rogue wave about high."The Story of the Fastnet"
– ''The Economist Magazine'' 18 December 2008

On 16 October 2017, a wind gust of was recorded at the lighthouse, during a tropical storm, Hurricane Ophelia. This is an Irish record, based on measurements going back to the 1860s. The previous record was at Malin Head during Hurricane Debbie in 1961.

Fastnet Rock

Fastnet Rock, or simply Fastnet, (possibly is also called ''Carraig Aonair'', meaning "lonely rock" in Irish). It is a small clay-slate islet with quartz veins, and rises to about above the low water mark and is separated from the much smaller Little Fastnet to the south by a wide channel. Fastnet is known as "Ireland's Teardrop", because it was the last part of Ireland that 19th-century Irish emigrants saw as they sailed to North America.

Fastnet also gives its name to the sea area used by the Shipping Forecasts transmitted by the BBC
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