Rotten Island lighthouse is a harbour light to light the passage from St. John's Point to inner channel and past the rocks to the anchorage within Killybegs Harbour, Donegal Bay, Ireland. It is operated by the Commissioners of Irish Lights.

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Rotten Island Lighthouse

The lighthouse in 2009
Location	Killybegs Harbour, Donegal Bay, Ireland
Coordinates	54°36′52.4″N 8°26′26.1″W
Tower
Constructed	1838
Construction	granite blocks tower
Automated	7 January 1959
Height	15 metres (49 ft)
Shape	tapered cylindrical tower
Markings	white tower, red gallery
Operator	Commissioners of Irish Lights
Light
First lit	1838
Focal height	20 metres (66 ft)
Lens	3rd order catoptric (original), 4th order cylindric refractor (current)
Intensity	White: 13,000 cd Red: 2,600 cd
Range	White: 15 nautical miles (28 km; 17 mi) Red 11 nautical miles (20 km; 13 mi)
Characteristic	Fl WR 4s
Ireland no.	CIL-1710

History

The Inspecting Commander of the Coastguard wrote to the Ballast Board on 21 April 1832 recommending that a light be placed on Drumanoo Point. George Halpin, Inspector to the Ballast Board, agreed that a light was necessary but he recommended Rotten Island instead. The Ballast Board then approved a light in 1833 and Statutory Sanction was obtained from Trinity House.

Design and construction

The lighthouse and keepers' houses were designed by George Halpin and the works were carried out by the Board's workers under his inspection. The conical tower of cut granite was painted white. The original light was a fixed white catoptric third order lens pointed to land 66 feet above high water and visible in clear weather for 12 miles. It was first exhibited on 1 September 1838 before completion. The cost at the end of 1839 amounted to £8,697.19s.4d.

On 15 September 1836 three men drowned while returning from work on the rock as their boat capsized.

Changes

In 1910 the fixed light was changed to a fifth order dioptric lens, flashing with a character of one flash every three seconds. This new light was introduced on 13 December 1910.

The station was automated on 7 January 1959 and the dioptric lens with its revolving machine and vaporised paraffin incandescent burner were replaced by a new fourth order cylindric refractor lens. Its mantle light source used dissolved acetylene from a battery of cylinders giving a candlepower of 2,600 white light and 500 in the red sector. This appeared to be worse than the old light and mariners using the harbour complained about the new lens.

The light was converted to electric on 1 February 1963 which increased the candlepower to 13,000 white and 2,600 in the red sector of the light. The character though remained the same, one flash every three seconds. If the electricity supply fails, an automatic changeover to batteries comes into operation and an acetylene standby can be fitted if the battery standby fails.

The character was changed to one flash every four seconds on 1 February 1965.

See also

• List of lighthouses in Ireland

References

• "Rotten Island". Commissioners of Irish Lights.
• Rowlett, Russ. "Lighthouses of Western Ireland (Ulster and Connacht)". The Lighthouse Directory. University of North Carolina at Chapel Hill.

External links

• Commissioners of Irish Lights