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www.sname.org/sname/mt Many builders are fabricating large, flat panels on laminating tables and then joining them to create ship modules. e at panels can be produced with enhanced levels of process control, including layout with overhead laser systems and 100% ultrasonic non-destructive evalu- ation (NDE). As much as marine composite construction is rened and automated, there is no getting around the fact that unlike metallic structures, the plating material itself is being created on the shop oor. erefore, represen- tative test laminates must be evaluated to ensure the anticipated mechanical properties are achieved. Visual inspection and advanced NDE techniques are critical in areas of high stress concentration, which are often high- lighted in FEA models. Environmental and health issues As noted earlier, resin infusion is a closed mold process that virtually eliminates worker exposure to VOCs. Secondary bonding used to join panels together may be done using hand layup techniques, in which case respirators with an independent air supply should be used. Dust from trim- ming operations is best collected at the source using tools equipped with vacuum pick-up hoses. Society is increasingly concerned with end-of-life issues associated with large marine structures. Experience has shown that composite boats survive longer than their machinery and outt, creating a big demand to renovate older, classic designs. Unlik e metals, composites cannot be easily recycled for reuse and today the most promising technology involves grinders that reduce unwanted com- posites into structural llers for reuse. With the proliferation of composite wind turbine blades that will reach the end of their useful life in a few decades, we can expect new, inno- vative composites recycling methods to emerge. Composite structures (especially sandwich laminates) have a lot more types of potential failure mechanisms than traditional metallic structures. And because composites are layered, damage is not always apparent using only visual inspection. A recent Ship Structure Committee report (which can be found at www.shipstructure.org/ pdf/463.pdf) cataloged defects and damage found in marine composites and the suitability of various NDE techniques for detecting the aws. e report concluded: By far and away, the best NDE tool for marine composites is still the human eye. Coupled with an experienced sur- veyor who understands how composite structures resist loads in a marine environment, damage is most often rst detected through visual inspection. However, visual inspection cannot reveal the extent of damage with cer- tainty. Defects or damage can exist deep within layers of a laminate, which may not be detected by looking at the sur- face. Sandwich laminates have additional failure modes that require advanced NDE methods, such as core failures and bondline deciencies. e initial assessment of NDE technologies revealed laser shearography, thermography, ultrasonic testing and digital tap hammers to be the most promising for marine composites inspection.? Repair Depending on the size of the failure, most repairs to marine composite structures can be accomplished with a mini- mum of specialized equipment and worker training. e primary objective is to achieve a good secondary bond from the repair resin system. is requires good surface prep- aration, adequate repair taper, and optimal laminating conditions. It is always desirable to replace damaged mate- rial with similar products. It may seem intuitive to make the The Turanor PlanetSolar is a 31 m wavepiercer catamaran with approximately 537 m 2 of solar panels on its deck that drive carbon ?ber propellers. Designer Craig Loomes from New Zealand speci?ed advanced carbon ?ber hull construction, and the boat completed a circumnavigation voyage in May 2012. Photo courtesy PlanetSolar SA. April 2013