Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pilot study reveals storm response of offshore lighthouses

09.12.2015

The unseen responses of remote offshore lighthouse in the face of severe storms are revealed in a new study by Plymouth University.

A team from the School of Marine Science and Engineering considered historical and contemporary observations of the wave impact loading on rock lighthouses during storm conditions.


The Douglass Tower is on the Eddystone Reef off the coast of South West England.

Credit: Helen Nance/Plymouth University

They combined these with data obtained in a pilot study on the Eddystone Lighthouse during the winter of 2013/14, and found the motion of the tower was smaller than might have been suggested by anecdotal observations.

However, the waves still pose a threat with measurements showing they climbed up to 40 metres up the side of a structure not regarded among the most vulnerable lighthouses in the British Isles, let alone globally.

The study, published in the journal Maritime Engineering, was led by Dr Alison Raby, Associate Professor (Reader) in Coastal Engineering at Plymouth University.

She said: "There are about 20 masonry lighthouses around the UK that are exposed to wave action. Although mariners are making ever greater use of satellite-based navigation technologies, the General Lighthouse Authorities recognise the need to retain rock lighthouses as physical aids to navigation. However, there is concern about how well they would withstand the additional wave loading associated with predicted sea level rises and increased storminess."

To assess current impacts, Plymouth University technicians installed a range of measuring equipment on the Douglass tower, the fourth lighthouse sited on the Eddystone Reef (around 14 miles off the coast of Plymouth) and in situ since 1882.

These included remote-controlled video cameras to record the wave conditions around the structure, together with geophone systems to measure any structural response.

Lighthouse engineers working on two other structures off the South West coast - Wolf Rock and Bishop Rock - also provided reports of the visual and physical effects of the storm, much as engineers have done for centuries.

The equipment recorded 2,978 individual events between 20 December 2013 and 14 March 2014, with a maximum wind speed in excess of 100mph and waves spreading up the face at a maximum of 50 metres per second.

Vibration measurements from the geophones gave maximum velocities of 5.5mm/s and highest displacements of around 0.07mm.

A structural model of the tower, validated by these field data, has been used to assess its stability and confirms the tower is within the safe limits for the worst wave measured during these storms.

However, more work is needed to ensure the stability of other rock towers to even more dramatic wave impacts, and funds to extend this research have been sought.

Dr Raby adds: "People look at lighthouses and wonder how they can absorb such colossal wave impacts. It is possible the current Eddystone Lighthouse responds less than other lighthouses, but while the cylindrical base of the lighthouse may reduce the wave run-up, video data shows it does not prevent water from jetting up above 40 metres. In this case, designers have potentially learned from previous mistakes, but this is far from the most exposed rock lighthouse and the curious effect of the particular rocky outcrops will mean other lighthouse responses to wave impacts will be quite different."

The results of further tests using the COAST laboratory at Plymouth University and a computational study are currently being analysed, while more advanced equipment is being fitted to Eddystone and additional instruments are being deployed at the Longships Lighthouse off Land's End.

Dr Raby will also be presenting the research at the annual International Association of Lighthouse Authorities' Engineering meeting in Paris in April 2016.

Media Contact

Alan Williams
alan.williams@plymouth.ac.uk
44-175-258-8004

 @PlymUni

http://www.plymouth.ac.uk 

Alan Williams | EurekAlert!

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Fraunhofer ISE Pushes World Record for Multicrystalline Silicon Solar Cells to 22.3 Percent

25.09.2017 | Power and Electrical Engineering

Usher syndrome: Gene therapy restores hearing and balance

25.09.2017 | Health and Medicine

An international team of physicists a coherent amplification effect in laser excited dielectrics

25.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>