Les Hanois Lighthouse

Les Hanois Lighthouse

Les Hanois Lighthouse during a volcanic ash sunset (April 2010)
Location	On Les Hanois, Guernsey
Coordinates	49°26′06.2″N 2°42′08.4″W / 49.435056°N 2.702333°WCoordinates: 49°26′06.2″N 2°42′08.4″W / 49.435056°N 2.702333°W
Year first constructed	1862
Automated	1996
Construction	granite tower
Tower shape	tapered cylindrical tower with balcony, lantern, keeper's quarter and helipad above the lantern
Markings / pattern	white tower
Height	36 m (118 ft)
Focal height	33 m (108 ft)
Current lens	4th order rotating optic
Light source	solar power
Intensity	89,900 candela
Range	20 nmi (37 km)
Characteristic	White group flashing twice, 3.2 seconds apart, every 13 seconds
Fog signal	Sounding twice every 60 seconds (range 2 nmi (3.7 km))
Admiralty number	A1580
NGA number	8180
ARLHS number	GUE-001

Les Hanois Lighthouse was constructed between 1860 and 1862 to a new design by James Douglass, and was first lit on 8 December 1862. It is sited on the rock known as Le Biseau,^[1] or Le Bisé,^[2] part of the reef Les Hanois one mile north west of Pleinmont where the Trinity House cottages were built. It was erected in response to an increasing number of shipwrecks on the treacherous rocks off the western coast of Guernsey, including the wreck of HMS Boreas ( Royal Navy) in 1807 ^[3] An article appeared in The Times on 15 July 1850 asking about the necessity of a Lighthouse at Pleinmont Point^[4]

The lighthouse was constructed in Cornish granite rather than stone from Guernsey. Cornish masons were employed to dress the stone on the castle pier in Saint Peter Port.^[2] Construction workers were accommodated in Fort Grey.

The tapered granite tower, painted white, is notable in terms of lighthouse engineering because it was the first to be built with all the stones dovetailed together both laterally and vertically, thereby making the construction a single solid mass. The cement mortar in the joints formed between stone faces lock the dovetails so that the stones cannot be separated without being broken. This method, used for the first time at the Hanois Lighthouse, became the pattern adopted for subsequent lighthouses built on sea rocks.

The helicopter pad on top of the lighthouse was built in 1979. The lighthouse was demanned in January 1996 following automation. Conversion to work from solar power required a slowing down of the optic, changing the character of the light, so as to reduce the power requirement and deliver the 20 nmi (37 km) range required.

Its role is to provide a mark warning of the reefs and rocks to the west of Guernsey and providing a position fix for vessels entering the Channel Traffic Separation Scheme.^[5]

The reef Les Hanois includes, besides Le Bisé and numerous small rocks, the following major rocks: Le Grand Hanois, Le Petit Hanois, La Percée, Round Rock and La Grosse Rocque.^[2]

View of the lighthouse and Les Hanois reef

See also

• List of lighthouses in the Channel Islands

References

1. "Le Hanois Lighthouse". Guernsey Scenes.
2. Coysh, Victor (1985). Channel Islets. Guernsey: Guernsey Press. ISBN 0902550128.
3. "100 men lost: HMS Boreas, 28 November 1807".
4. "SHIP NEWS Pleinmont Point, Guernsey, Necessity of a Lighthouse.". The Times. 15 July 1850. p. 7a.
5. "Les Hanois Lighthouse". Trinity House.