An EU project has concluded that shipyards could at a stroke reduce their impact on the environment and become more competitive by moving away from welding and using adhesive bonding for joining lightweight materials.
The initiative, led by UK shipbuilder Vosper Thornycroft, brought together 13 partners from across Europe, including Danish ferry operator Stena, the Fraunhofer Institute, the UK’s University of Southampton, and Italian shipbuilder Fincatieri.
After studying the production of passenger ships, ferries and high-speed craft the group concluded that on large passenger ships, adhesive bonding could provide a cost saving of at least 20 per cent for the fastening of supports, stiffeners and other attachments.
Meanwhile, for a patrol craft, reductions in building costs through the use of adhesive bonding in the superstructure could be expected to be around 25-30 per cent. While for fast ferries, the group claimed that adhesives could enable an overall weight reduction of between 4.5 and nine tonnes.
It is estimated that over 20 years these reductions could save between 8,000 to 16,000 tonnes of diesel, which at current fuel prices would be worth between e1.6m and e3.2m (£1.1m and £2.2).
The added benefit of adhesive bonding is that it will reduce the amount of welding slag created. Project co-ordinator Ajay Kapadia, from VT’s Composite Technology Centre explained: ‘It has been estimated that a medium size shipyard produces about 60 tonnes of welding slag a year; this is considered special waste for which a controlled disposal is required. To help reduce this significantly the focus of the project was on aluminium-aluminium, aluminium-steel and aluminium-composite joints.’
The group also suggested that the widespread use of adhesive bonding could lead to considerable improvements of the working conditions in shipbuilding facilities. This is because use of adhesives calls for a strictly controlled environment. Plus, bonded connections are straight and don’t require the kind of filling and sanding re-work usually needed after welding. This, claimed the group, will reduce the risk from noxious fumes and reduce the potential for explosions often triggered by the heat from welding operations.
‘Adhesive bonding will have a significant impact on current shipbuilding practice of passenger ships.’
‘It will trigger considerable future development far beyond the scope of the project by opening up new possibilities for all types of modular construction,’ said Kapadia.
Malcolm Courts, R&D manager at Vosper Thornycroft, added that although he was unaware of any examples of the findings already being applied to ship manufacture the technology is mature enough to be used on the right kind of boats. He explained that these would typically be lighter boats with aluminium superstructures.