NDT corrosion mapping for superyachts

Brookes Bell has been working in the superyacht sector for over 30 years, our extensive maritime experience and expertise enables us to pull in different experts to identify and maximise opportunities for owners and managers whether that’s for a new build, rebuild or refit. The latest development for the sector is the adaptation of Advanced Non-Destructive Testing (NDT) technology for superyachts.


One of the biggest challenges facing superyacht yards and management companies is the difficulty of producing an all-encompassing and accurate quote for works during a refit or rebuild. A superyacht deck - regardless of whether it has a painted finish, is plastic or teak – can hide corrosion and damage as a result of water ingress. The inside of a vessel is very busy, packed with cables and important equipment, similarly the fit out is high quality and expensive. Too often it’s impossible to assess the damage without ripping up and destroying the extremely expensive structure.

But not now, using Brookes Bell’s Advanced NDT techniques it is possible to accurately inspect, assess and accurately estimate the work required. The inspection method is driven by pulsed eddy current (PEC) technology inside a probe which scans a non-ferrous coating to accurately assess the state of the steel plate underneath. It can ‘see through’ a teak deck, through paint, antifouling and cladding to identify any problems underneath. The technology has been used for some time in the oil and gas industry and by the military. PEC scans have been used to inspect rig legs seeing through the weather jacket, to examine submarines looking through the rubber tiles and to assess the condition of the steel under the insulation on oil and gas pipelines.

On a superyacht, while the technology is complex, conducting a scan is straightforward and the resulting data is easy to understand, clearly displaying any diminution of the steel plate and therefore any areas of concern. PEC Deck Scans can be done at up to 150mm per second with a scan width up to 450mm, meaning vast areas can be covered in a relatively short time frame. Different sensors are used to detect steel wall thinning and corrosion attack. Depending upon the area to be scanned, a large probe may be used which is the size of a wide headed vacuum cleaner or a smaller ‘mouse like’ probe which allows access to small areas such as tight corners and around fittings. The data provides a residual thickness reading and calculates wastage due to corrosion.

The results are then plotted on to a coloured ‘map’ of the deck, highlighting areas of concern. A simple colour spectrum gives a comprehensive, understandable ‘at a glance’ view as well as the detail needed to assess the size of the issue: with blue (good and sound) through to green, yellow and orange (an area of concern) to red (bad, damaged and needing attention). The plotted map also shows the structure underneath a superyacht’s deck plate, highlighting the stiffeners, frames etc in the image as heavy dark blue lines and the data can be applied to a 3D model, allowing it to be twisted and turned for inspection by the customer. This really is corrosion mapping at its best.

Launched in November last year, Brookes Bell’s PEC scans have already been used for investigations on numerous small yachts, while the biggest yacht to be examined to date has been 90 metres long. Brookes Bell is also planning to use the technology to help a charitable trust which has been set up to restore the hull structure of an old Clyde steamer from the 1930s, the TS Queen Mary. The scans will offer valuable insight into the condition of the vessel and the work needed to turn it into a museum ship in Glasgow.

Patrick Yeoward, a member of the superyacht team, has worked in the superyacht sector for many years, including as a manager of vessels and so he understands the concerns of the owners, shipyards and management companies.

He explains: “This really is exciting, for the first time, the owner and captain can clearly see the extent of any underlying problem and can accurately plan for the upcoming works – this is good news for both budgets and the environment. The scan produces clear colour coded diagrams showing the areas of concern, so any repairs can be specific, localised and wastage minimised.

“The management company can – with the accurate information – plan the timeframe, budgets and contractors, while the yard knows the scope of the works, the budgets, the manpower needed and any contractor requirements. Everyone involved, really does benefit from the accurate information and insight this technology provides.” Patrick says that the next step is to develop the technology for use on aluminium, tests are ongoing and the technology should be ready towards the end of this year. It would allow Brookes Bell to offer the service to the larger yachts which have a steel hull with aluminium superstructure, giving a comprehensive overview of the condition of the vessel.

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