STORMLAMP – A research project measuring the impact of waves on historic rock mounted lighthouses

Author: Eve Allen

STORMLAMP is a research project that monitors and measures the impact of waves on the structural performance of lighthouses.

The project began in May 2016 and has focused on six lighthouses spread across the British Isles. These lighthouses were selected due to the particularly extreme wave environments that surround them and their unique structural elements or operational issues.

The STORMLAMP project is a great example of how engineering can benefit communities, trade and heritage. Historic rock-mounted lighthouses continue to play an essential role in the safe navigation around perilous reefs. However, their longevity is threatened by the battering of waves which may be set to increase with climate change. Virtual navigational aids such as GPS are fallible, and reliance on them can be disastrous. Mariners will continue to need lighthouses as these physical visual aids are strategically placed to assist navigation. The loss of any reef lighthouse will be incalculable in terms of safety, commerce and heritage.

A person stood on a helipad by the coast flies a drone.
James Bassitt (University of Exeter) operating Phantom drone from helipad at Fastnet Lighthouse

This complex project requires a unique combination of skills available from three UK universities: University College London (UCL), University of Exeter and University of Plymouth.

Three people sit in knee deep water in the COAST laboratory simulator. A model lighthouse at scale 1:40 is in the foreground.
Alison Raby (University of Plymouth), Dassa Dassanayake (University of Plymouth), Peter Dobson (Trinity House) in the COAST Laboratory at University of Plymouth.

University of Plymouth works on predicting extreme storm conditions for offshore rock lighthouses using long-term metoceanic data. Plymouth also carries out physical tests using scale models of lighthouses and uses Computational Fluid Dynamics modelling to identify how wave loading interacts with these rock structures. University of Exeter accesses the lighthouses for installing monitoring systems and performing modal analysis in order to identify the structural characteristics of the lighthouses. Finally, UCL uses the data produced from the other two universities to carry out detailed structural analysis to assess how resilient the lighthouses are under extreme wave impacts.

One of the lighthouses STORMLAMP is investigating is Wolf Rock, which lies about 8 miles from Land’s End. The tower is built upon a rocky pinnacle which is completely obscured at high tide and was selected for long-term monitoring by STORMLAMP due to the unbroken Atlantic waves it encounters. It’s one of the larger towers in the project at 41m and was built in 1869. As with many of the lighthouses access is via helicopter, landing on the helideck at the top of the tower. Modal testing took place in 18 July 2016 and James Bassitt, based at University of Exeter took some fantastic footage from the helicopter flight to Wolf Rock.

A sequence of five images show tests conducted on the 1:40 scale model lighthouse.
Wave impact tests with the 1:40 scale model of Wolf Rock lighthouse in the COAST Laboratory at the University of Plymouth

As the four-year project comes to a close, a final workshop is planned for May 2020 to showcase the STORMLAMP research to a wider audience. The workshop will involve presentations on lighthouse research and relevant areas from academics, heritage professionals and industry stakeholders, as well as discussions on future directions for related research.

To find out more about the project and the lighthouses STORMLAMP has been working with, visit the  website. There are plenty more pictures of the team in action and details of our partners and of course the lighthouses themselves.

https://stormlamp.org.uk/ 

@stormlamp_edu

Excavating the Rooswijk … virtually!

The next blog in our British Science Week 2020 series come from MSDS Marine, a Marine and Coastal Contractor specialising in the management, execution and support of archaeological projects in the marine environment. 

The Rooswijk was a Dutch East India Company vessel which sank on the treacherous Goodwin Sands, off Kent, in January 1740. The ship was outward-bound for Batavia (modern-day Jakarta) with trade goods. The site is now protected by the Protection of Wrecks Act 1973. The ship’s remains are owned by the Dutch Government; however, the UK government is responsible for managing shipwrecks in British waters, therefore both countries work closely together to manage and protect the wreck site.

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Figure 1. Clockwise from top left: Multibeam image showing the main area of wreckage on the Rooswijk, A diver excavating in 2018. Lead project Conservator Angela Middleton examining a concreted chest from the side. A screenshot of the Rooswijk virtual trail.

A two-year archaeological excavation project was undertaken between 2017 and 2018 due to the site being at high risk of loss through environmental changes and unauthorised diving. Wrecks such as the Rooswijk are part of the shared cultural maritime heritage across Europe and it’s important that cultural heritage agencies are able to work together to ensure that sites like this are protected, researched, understood and appreciated by all. The project involves an international team led by The Cultural Heritage Agency of the Netherlands (RCE) in partnership with Historic England. MSDS Marine are the UK Project Managers for the project.

In 2019 MSDS Marine, working with ArtasMedia, created a virtual tour of the site: https://msdsmarine.com/projects/dive-trails/rooswijk-virtual-trail/. Now the projects archaeologists are working with the μ-VIS X-ray Imaging Centre at the University of Southampton to further excavate the site virtually!

A number of stacks of coins were found during the excavation. Some of these were carefully separated by the conservators from the Investigative Science Team at Historic England (Figure 2). Some could not be separated.

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Figure 2. An MSDS Marine conservator separating coins from the Rooswijk in the Historic England laboratory.

A number of stacks were then sent to the μ-VIS X-ray Imaging Centre (www.muvis.org) at the University of Southampton to be micro-CT scanned. X-ray micro-Computed Tomography (µ-CT) scanning is a volumetric scanning technique, which enables us to virtually cut open materials to look inside with micrometre spatial resolution, while preserving the condition of the object we are scanning. During the scan, the object is rotated 360 degrees as thousands of 2D X-ray projection images are acquired. These 2D images are then reconstructed into a three-dimensional volume, which is made up of cubic pixels with intensities related to the amount of x-ray energy absorbed at that point.

We used the custom walk-in scanner (the Hutch) at the µ-VIS X-ray Imaging Centre to scan the concreted coins, which were stacked in sealed tubes to prevent excessive drying during the scanning process (Figure 3).

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Figure 3. Concreted coins mounted for µ-CT scanning within the custom Nikon/X-tek 450/225 kVp Hutch at the µ-VIS X-ray Imaging Centre, University of Southampton

The digital reconstructed volumes were then sent to MSDS Marine, where myVGL software (Volume Graphics GmbH, Germany) was used to manipulate the volume data, so that the individual faces inside the stacks could be seen (Figure 4). These coin faces have not been seen since they were packed into chests for the voyage almost 280 years ago.

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Figure 4. A Rider coin from 1739 that has been virtually separated from a large coin stack.

The coin face slice images will be sent to Jan Pelsdonk, the projects numismatist, for identification and will contribute to the understanding of the wreck.

The application of scientific techniques like CT scanning and digital model processing have contributed hugely to the understanding of underwater heritage, and continue to offer new and exciting ways of investigating these important cultural sites.

Phoebe Ronn, MSDS Marine Phoebe@MSDSMarine.co.uk

www.MSDSMarine.co.uk

Katy Rankin, µ-VIS X-ray Imaging Centre, University of Southampton, k.rankin@soton.ac.uk

www.southampton.ac.uk/muvis