In-depth | COATINGS
Figure 8: Simulated timelines for a dry docking in which a 10000m2
hull coated
with conventional AF is to be converted to a FR system compared to coatings that are reapplied with a conventional antifouling system (20o
C). No painting is assumed to take place during the night time (except for priming after spot blasting). NEXUS X-Seal shows 37% time savings compared to the current full blasting procedures (waiting times depicted as blanks). This is equivalent to roughly two days or US$400,000 using Singapore prices for blasting, washing, paint application and dock rent. It is also one day faster than a re-docking using a linkcoat+tiecoat sealer system. As shown in the graph, a Fouling Release conversion with X-Seal is in level with a conventional antifouling application.
Figure 9: Mixed substrates exposed after hydrojetting of mechanical damage before coating application (left). Final result when conventional tie-coats are used for the touch-up (right) showing deficient adhesion at the transition edges.
In the long run, and as the Figure 10: Simulated timelines for a silicone overcoating project at 20o C (10000 m2 hull;
waiting times depicted as blanks). The maintenance tie-coat NEXUS X-Tend is compared to traditional tie-coats such as NEXUS (top) showing an 20% time saving (equivalent to roughly one day or US$100,000 using Singapore prices for blasting, washing, paint application and dock rent). The hull area to be hydrojetted (step 3) is reduced since NEXUS X-Tend is tolerant to well-prepared old epoxy and tie-coats, so only severe damages needs to be repaired. X-Tend brings the docking times down to the level of a conventional AF redocking thanks to the simplified repair steps and the lower number of full coats. The above time comparison has been done following normal working hours and overcoating intervals for the different products.
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performance of FR products is optimized even further, it is likely that this technology will become the preferred choice both from the economical and environmental points of view. In order to satisfy the more conservative customers unwilling to invest in state-of-the-art coatings, biocide-based products are still expected to stay in the market for many years to come. However, these products will need to continuously reinvent themselves in order to meet tighter legislation, e.g. using lower amounts of efficient yet more environmentally friendly active ingredients, safeguarding low emissions of exhaust gases and preventing the spread of non-indigenous species, etc. The coming years will witness whether marine paint companies will succeed in dramatically improving the environmental profile of their biocide-based products while keeping performance levels similar to that already achieved by the best non-toxic
The Naval Architect January 2011
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