Gurit USA, a Bristol, R.I.-based subsidiary of the global composites supplier Gurit, engineered new tools for the larger Boston Whaler boat. The two companies performed extensive finite element analysis on the molds to make sure they would satisfy performance requirements and fit within space constraints. In particular, the frame height had to be such that it avoided ceiling clearance issues when the liner mold was hoisted up and then set into place.
With the design done, Boston Whaler approached Marine Concepts to build the specified molds. Biddison notes that the molds were large and subject to intense pressure during the boat building process, requiring certain steps be taken.
“After the body of the mold was infused, we stiffened the molds with infused cored flat panels that were 5-axis machined to match the contour of the geometry and then affixed a steel exoskeleton with structural adhesives,” he says. “Similar processes have been employed on some of our aerospace parts manufacturing with great success.”
While being lifted up from each end, rotated 180 degrees and then lowered into the hull, the liner could not deflect more than a quarter of an inch. The materials used in the liner mold are confidential, as are some of the other details such as the curing temperatures. “The latest high-temp infusion resins were used, along with glass- and infusion-related materials, to ensure a steady and even flow for complete wet out,” Biddison says.
Due to the complexity of the project, Marine Concepts contracted with Composites Consulting Group. The company supplied computer flow modeling expertise, infusion engineering, flow modelling, onsite training and oversight of the material installation and infusion process, says Dean Callander, process specialist at the De Soto, Texas, company.