Cameras on the Wolf Rock lighthouse, 8 miles off Land’s End, are now set to capture storm wave activity around the tower. Earlier this summer the STORMLAMP project commissioned marine instrumentation experts Mr Peter Ganderton and Dr Alex Nimmo-Smith of the School of Biological and Marine Sciences at the University of Plymouth to develop a low-power and remote-controlled stereo imaging system. They received guidance on the camera set-up from Dr Alvise Benetazzo from the Institute of Marine Sciences, ISMAR – CNR in Venice who has recently designed a similar system for La Jument lighthouse in Brittany, and others on fixed platforms and moving vessels.
The technical bit…
The system comprises 2 synchronised cameras and a mini computer for logging data, with bespoke software for data logging and control. To provide protection from the harsh environment the camera housings are rated IP66 (water protection from powerful jets) and all the control hardware is housed in an industry standard waterproof/crushproof case. The system is controlled via a 4G network that links to the Cape Cornwall Coastwatch station and then to the University of Plymouth. Two cameras with overlapping fields of view permit, via a complex algorithm, the extraction of quantitative wave data to be used in wave-structure interaction analysis of the lighthouse.
When storm waves crash onto the lighthouse they cause it to vibrate; these are sometimes discernible to personnel on station. Using a structural monitoring system already installed on the lighthouse as part of the STORMLAMP project, the vibration data gets sent back to the University of Exeter. The data is combined with information about the characteristics of the structure obtained from earlier field vibration testing. This linking of information allows the determination of the wave load that must have caused a particular vibration. Results from this so-called inverse analysis will in the future be combined with the camera system to provide the full story: the size of the wave as it comes crashing over the rocks, the wave load as it pounds against the tower and then the resulting vibration. It’s rare to get such detailed information at such a challenging site, but that’s what you get when you bring the very best people together on an engineering project. Now we just wait for the Atlantic storms to roll in.