Carbon Fiber Makes Ship-to-shore Crossings More Stable
Traditional wood and metal gangways have been heavy and, therefore, both hard to handle and narrow — the latter to save weight. Exit Engineering (Fiesso d'Artico, Italy) has developed several carbon composite gangways — the latest, a 350 cm/138 inch model targeted at the larger yacht market. At 60 cm/23.6 in wide, it's 50 percent wider than comparable products but weighs only 13 kg/29 lb. The hinged structure folds in half for easy stowage and can be deployed by a single deckhand, eliminating the costly, heavy hydraulics often used to operate boarding systems. The 350 joins the company's smaller 216-cm/5.1-kg (85-inch/11.2-lb) folding model and a superlight one-piece 220-cm/87-inch model that weighs only 3.8 kg/8.4 lb.
The gangway is made using unidirectional and 2x2 twill carbon/epoxy prepregs from G. Angeloni srl (Quarto d'Altino, Italy) layed up over female molds. Molds and parts are made by custom molder Re Fraschini Components srl (Legnano, Italy). Molds are fabricated from carbon fiber tooling prepregs and pulled from master models CNC-machined from TB620 epoxy tooling blocks supplied by Advanced Composites Group Ltd. (Heanor, Derbyshire, U.K.). The gangway sections are modified C-beams cored with Nomex honeycomb (DuPont Advanced Fiber Systems (Wilmington, Del.) in the walking area to optimize stiffness, says Exit's technical director Giuseppe Bottacin. The sandwich construction virtually eliminates deformation for greater passenger comfort. The corresponding halves of the hinges are layed up and comolded with the structures, eliminating the need for post-mold bonding. The holes for the hinge pins are created in mold, eliminating drilling. The structure is vacuum bagged and autoclave cured at 120°C/248°F for 70 to 100 minutes.
After curing, the structures are sent to the company's workshop in Fiesso d'Artico where metal fittings are adhesive bonded for the nylon wheels and aluminum deck fitting, pad eyes and a locking system that prevents the gangway from folding during service. Standard gangways are finished with a transparent coating to display the carbon fiber weave, but Exit will custom paint with any color the customer chooses, Bottacin says. A spray-on antiskid paint from G. Angeloni is applied on the traffic surface.
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