Engineers at the University of Plymouth have transformed a wave tank into the Atlantic Ocean and created a scale model of one of the country’s most iconic lighthouses.
Standing a little more than 87cm high, the model of Wolf Rock has been battered by simulated waves as part of a research project investigating the resilience of a number of rock lighthouses.
The project – STORMLAMP – is being led by the University in conjunction with the University of Exeter and UCL, the UK and Irish General Lighthouse Authorities, and industrial partners HR Wallingford, AECOM, WS Atkins and the Environment Agency. Funded by the Engineering and Physical Sciences Research Council (EPSRC), the investigators are using a combination of numerical modelling and field tests to demonstrate the effects of repeated impulsive wave loading.
“The real Wolf Rock is situated at the most exposed of locations,”
said Professor Alison Raby, project lead.
“It is on a pinnacle of rock surrounded by deep water, which means that it can experience some very large breaking wave impacts. Building this model and testing it here in the COAST Lab enables us to refine the numerical models we are using alongside data gathered in the field.”
Technician Kieran Monk and postdoctoral researcher Dr Darshana Dassanayake built the model over two weeks, in the Ocean Basin of the COAST Lab, situated in the Marine Building. First they constructed a wooden base, equivalent to the Wolf Rock itself, from marine plywood and pine batons. Next came the structure, manufactured by 3D printing at 1/40th the scale of the actual lighthouse.
The model has since been subjected to different wave patterns and the results recorded on camera, and via surface elevation gauges, pressure transducers, load cells and accelerometers.
“It was not until we started generating waves that we realised that they had a tendency to rotate around the model and meet again over the area where the boat landing is located,”
Professor Raby said.
“This might explain why that area has had a tendency to be damaged during storms.”
Wolf Rock lighthouse is located eight nautical miles south west of Land’s End, Cornwall (and 18 nautical miles east of St Mary's, Isles of Scilly), on a rock whose fissures create a howling sound in strong winds, lending it its name. Standing 41 metres high, it was built in the 1860s from Cornish granite, and has been fully automated since 1988. Despite this, engineers are still required to access the lighthouse, which is why owners Trinity House fitted a helipad to the top of the structure.
The University has been studying lighthouses for eight years, initially on a pilot project at the Eddystone Lighthouse, before STORMLAMP extended the study to include Wolf Rock, Bishop Rock, and Longships, in Cornwall; Les Hanois, in the English Channel near Guernsey; Fastnet, to the south of Ireland; and Dubh Artach, off the west coast of Scotland.
“Ultimately STORMLAMP will enable Trinity House to make informed decisions about the future of its lighthouses,”
adds Professor Raby.
“And what we are seeing is that although many are at the theoretical limit of their lifespan, the ingenuity of their design is such that they are weathering the worst of the elements. And the results will be of interest not only to other lighthouse operators, but for those with responsibility for different types of heritage structure, such as bridges and breakwaters.”