#LA JUMENT LIGHTHOUSE KEEPER SERIES#

La Jument was completed in 1911 after 8 years of construction. about 1.2вЂ‰km in the northwest of La Jument).

( d) Wave rose from the wave climatology presented in the paper (location of the extraction: 48в‚5вЂІ35 вЂІвЂІвЂ‰N, 5в‡вЂІ50 вЂІвЂІвЂ‰W, i.e. The current elevation above chart datum of the substructure is virtually shown here (14вЂ‰m) as it is a key element for the paper. ( c) Historical plan of La Jument, before the addition of the final substructure. The substructure added to the lighthouse to solve its early-life stability issues is well visible. ( a) in calm wave conditions but with intense spring tide currents causing eddies in the wake of the lighthouse. These waves that shoal over the very steep foreshore bathymetry may violently break over the lighthouse and generate sea spray that can run up well over the lighthouse lantern (see the helicopter video recording available as electronic supplementary material).ДЇigure 1. La Jument's photogenic quality is tightly related to its extreme exposure to North East Atlantic storm waves.

#LA JUMENT LIGHTHOUSE KEEPER SERIES#

A series of pictures taken from a helicopter by Jean Guichard, showing the lighthouse keeper opening the door while a giant wave engulfs the substructure is famous worldwide. Among the threatened offshore lighthouses, La Jument, located offshore of Ushant island, Western Brittany, France ( figure 1) is one of the most iconic. During the most extreme storms, breaking waves impacts threaten the lighthouses' structural integrity, which raises the question of the remaining lifetime of these fascinating monuments. Indeed, because the lighthouses at sea are constructed upon shallow rocky platforms they are exposed to breaking waves responsible for intense and transient forces, also known as вЂslammingвЂ™ impacts.

Among these environmental forcings, the wave loading generally dominates by far the winds or current actions on the structure. Offshore lighthouses at sea represent examples of engineering marvels, by overcoming challenges of constructing robust structures to withstand the extreme environmental loading they have to face for decades or even centuries. This article is part of the theme issue вЂEnvironmental loading of heritage structuresвЂ™. This offers a possible second service life for these heritage structures as in situ laboratories dedicated to the study of the coastal hydrodynamics and its interaction with marine structures. This paper reveals the potential for conducting ambitious field experiments from offshore lighthouses in order to collect valuable storm waves and wave loading observations.

Our observations suggest that this giant wave (19вЂ‰m high) had a crest elevation high enough to directly hit the lighthouse tower, above the substructure. Thanks to stereo-video wave measurements synchronized to the acceleration record we were able to identify and describe the breaking wave responsible for this intense loading. Data analysis focuses on a storm event marked by a strong peak in the horizontal accelerations measured inside La Jument. The experiment, conducted at La Jument, an iconic French offshore lighthouse, featured several records of wave, current and structure accelerations acquired during severe storm conditions, with individual waves as high as 24вЂ‰m. This paper presents results from an experiment designed to improve the understanding of the relationship between extreme breaking waves and their mechanical loading on heritage offshore lighthouses.

La jument lighthouse keeper