Feature 2 | MARINE COMPOSITES
traditional fibre-glass reinforcement, the use of carbon fibre can produce four times the rigidity and 2-3 times the tensile strength.
TeChniCAl PARTiCulARs Valö
length, oa.........................................27.00m length, wl..........................................25.20m Beam, oa.............................................8.40m Depth, mld ..........................................2.70m Draught................................................0.95m Gross tonnage ....................................231grt Deadweight...................................19tonnes Capacities - Fuel................................................3000litres - lube oil ...........................................250litres - Fresh water...................................1400litres - sullage............................................900litres - Bilge ................................................100litres Passengers............................................... 163 Crew............................................................. 3 speed
- 2x809kW............................................31.5kts - 2x749kW............................................30.5kts - service............................................27-27kts Main engines..............2x MAn D2842 le410 749kW at 2100rpm
Auxiliary power ............. 2x Kohler 28eFOZD 26kW
Propulsion ...........2x servogear 9P805 cpps evacuation system ..........2x undertun uiAs Mes sR 150 marine evacuation systems Classification .................... DnV 1A1 hslC R4 Passenger e0
Brødrene Aa uses a vacuum infusion
process to form the hull. Te infusion process utilises a vacuum bag on an open mold. Resin is drawn by vacuum pressure into the mold and saturates the dry fibre reinforcement and core material. A porous media with high flow
resistance is needed to get the resin into the part. Much like Diab’s Core Infusion process, Brødrene Aa’s vacuum infusion process is based on using the core as a transfer medium. Resin flow and wet-out of reinforcements is achieved using a groove pattern on one side combined with perforations. As the structural laminate is practically
saturated from the core and out towards the surface, the surface cells in the core are properly saturated and so a strong bond between the core and structural laminate is achieved. It is not necessary to use peel-ply to
remove the vacuum bag. However, if secondary bonding is required (e.g. the bulkheads) it may be preferable to use peel ply in these areas. The vacuum core infusion process
offers very high flow rates, uses only high-quality laminates and produces no excess materials. Brødrene Aa first started using vacuum
infusion in 1997 when it built the nose cones for Norway’s airport-train and intercity train. By 1999, the boat builder had already infused a 30tonne offshore construction in “one shot”, using 22tonnes of fibre and 8tonnes of resin. “Te way of doing
The core acts as a transfer medium, resin flow and wet-out of reinforcements is achieved using a groove pattern on one side combined with perforations (Credit: Diab Group).
infusion is under continuous development and Brødrene Aa have developed their own methods, not unlike Diab’s way by using the core as the transport medium for the resin,” says Tor Øyvin Aa. Brødrene Aa has been using carbon-
fibre sandwich composites now for nearly 10 years and has not encountered any difficulties with the switch in materials. However, Brødrene Aa’s Tor Øyvin Aa states that the use of carbon fibre involves many more considerations. Quality is a major issue, the manufacturer must be very aware of using the correct combinations of resins and fibres and of treating them at the correct temperatures. The particular materials used in the construction of Valö’s hull are Torray T700SC FOE carbon fibre and Norpol
The 27m high-speed catamaran Valö went into service on three weeks earlier than scheduled (Credit: Brødrene Aa). 44 Ship & Boat International July/August 2010
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