ADVERTORIAL


SEEING THE INVISIBLE Tony Dale looks at improving yacht hull inspections with thermography


W


ith the help of Tony Dale, MD of Geo Therm as his 20+ years of experience in this field, we look at the use of thermal imaging to provide enhanced hull inspections, rather than traditional labour intense methods.


A tried and tested technique to differentiate structural integrity in fibre-reinforced plastic (FRP) hulls is to apply a consistent low- impact force using a plastic or rubber headed sounding hammer. This impact- echo response is immediate, exciting vibrations of delamination and differing tonal reverberations evident as a hollow sound for voids.


Although effective, the technique needs a sensitive ear and must be repeated over the entire hull surface by a competent inspector. This technique can potentially lead to unwarranted damage, furthermore, it is time consuming and difficult to uncover the total damaged area by hammer tapping alone – and is often combined with moisture


meter readings and exploratory destructive testing such as core sampling, gel-coat removal, drilling and grinding to differentiate the extent of the affected area.


Thermography or thermal imaging is very different, it is a non-invasive technique using thermal cameras to sense the invisible infrared (IR) range in the electromagnetic spectrum to detect, display and record in real time the surface thermal patterns, to locate and map damaged areas and moisture intrusion.


Thermal IR imaging cameras convert heat emitted from a surface into a two-dimensional false-colour image called a Thermograph, wherein thermal patterns (and accurate temperature values) are represented by varying shades of grey or colour, that emphasise thermal anomalies.


With a suitable thermal imaging camera, an entire surface area of a yacht hull can be systematically scanned relatively quickly.


However, accurate thermal acquisition, or how to set the thermal imager parameters, heat transference principles and experience on what to look for all require appropriate IR training,


Using thermal imaging it is possible to:


• Investigate the entire hull area quickly - to classify and quantify immediate risks


• Identify pending failure zones - where no trouble was suspected


• Justify works by adopting a risk-rank methodology – IR justification is obvious and unquestionable


• Follow-up after corrective repairs - re- scan and document


In summary, thermography provides an accurate, low risk, timely means to quickly locate surface and sub-surface anomalies for damaged, resin starved laminate, voids, cracks, crushes, and fractures in FRP hulls.


For more details Tel: +44 (0)1502 723241 or visit www.geothermltd.co.uk/marine


ONBOARD | AUTUMN 2022 | 29


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