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The luxury fibreglass catamaran boatbuilder Mattia, based in Lecco on Lake Como, northern Italy, recently launched the Mattia 60, an ocean going sailing catamaran, designed to offer greater speed and manoeuvrability.
After extensive investigations into composite materials and processing options the end result is a reengineered fibreglass craft, 19 metre (62ft) long by 9 metre (30ft) wide with a 23 metre high mast which displaces only 17,000kg and is capable of sailing at up to 23 knots. By using a combination of vacuum infusion for the composite hull and deck, high performance SAN sandwich foam cores, plus using a structural adhesive to bond the hull bulkheads and to fix the deck to the hull, the weight of the catamaran was reduced by 2000kg. With a new Mattia 60 retailing at around Euro 1.5 million, only high quality materials and the latest infusion technology have been used to achieve the exceptional build quality and long term performance.
Laminate Design and Material Selection
To provide a high quality, marine approved laminate construction for the hull and deck which Mattia was confident would provide reliable, long term performance, Crystic VE679-03PA a low shrink, long gel time infusion grade resin, was specified in combination with Crystic VE679PA skincoat behind a marine grade ISO/NPG gelcoat; the Crystic infusion resin and skincoat are both DCPD modified vinyl ester (VE) resins developed and manufactured by Scott Bader. These DCPD modified vinyl ester resins provide the additional benefit of an improved aesthetic finish due to lower print through. In critical performance areas of the superstructure which are subject to very high stresses and loads, such as the slamming area of the hull, sandwich laminate sections using CorecellTM M foam cores from SP-High Modulus were specified and formed part of the final infused hull and deck design. Corecell™ M-Foam provides a combination of high shear strength with low density, high elongation, high temperature resistance and low resin uptake.
Infusion Process Benefits
At the design and construction phase, Mattia took advice from its supplier partners about the latest composite process technologies and techniques available to manufacture lighter and stronger large section fibreglass constructions. Resintex Technology, which specializes in closed mould technology and supplying composite raw materials and ancillaries to the Italian marine market, work in close collaboration with Richmond Aerovac Italy. They recommended vacuum bagging as the optimum infusion process to consistently and cost effective produce high quality lighter weight, high performance very large composite parts, such as the 19 meter long hull and decks fibreglass sections. Manufacturing by infusion provided the added major benefits of reducing overall labour costs by over 25% and significantly improving shop floor health and safety conditions for the workforce; compared to open moulding, styrene volatile organic compounds (VOC) emissions were reduced by over 70% in both shipyards when they switched to vacuum bagging.
By designing the new Mattia 60 hull and deck around a vacuum bagging process Simonplast and Elvideo Giovanetti, the two Italian shipyard manufactures who produce the hulls and the decks for the Mattia 60, were able to make significant laminate performance and processing improvements compared with their traditional hand layup open moulding process. Infused parts were significantly lighter as less resin was used and more evenly distributed through the laminate. Tests carried out proved that higher mechanical properties were achieved in the infused laminate and parts were able to be produced with a much greater consistency. Mr. Simone Piscitelli, Production Director of Simonplast, the Mattia 60 hull manufacturer commented: “For such a large and complex vacuum bagging set up, when the infusion process is started it is essential that the resin has a predictable, controllable and reliable long gel time whatever the time of year. We trust Crystic VE 679-03PA pre accelerated resin to perform as stated in the technical data sheet. We have been able to consistently produce high quality vacuum infused hulls with an excellent laminate finish.” According to Scott Bader’s datasheet, based on using a 2% by weight recommended catalyst, depending on the ambient temperature the geltime for Crystic VE 679-03PA can be as long as 195 minutes at 15 deg. C down to 80 minutes at 25 deg. C
Structural Adhesive Reduces Weight
To make further reductions in the overall weight of the catamaran, Mattia approved the use of Scott Bader’s Crystic Crestomer 1152PA, which has Lloyds Acceptance, DNV and RINA approvals for GRP marine bonding applications. By bonding in bulkheads instead of over laminating further significant reductions to the weight of the hull were achieved in the new design, while at the same time improving the overall mechanical performance of the hull construction; Crestomer 1152PA adhesive has a much higher flexural modulus and ultimate tensile strength than the fibreglass laminate sections being bonded together. A significant reduction in production time was also achieved by bonding instead of over laminating. Having been successfully used for many years by Azimut and many other major GRP boat builders, Resintex was very confident to recommend to Mattia the use of Crestomer in these proven structural bonding applications.
More information:www.resintex.it - www.scottbader.com - www.mattia.it