It looks like smooth sailing for Netherlands-based Damen Shipyards’ new Waterbus 2407 after its May launch. Damen received its first order for four of its urban water shuttles in July from Aqualiner, an urban ferry service provider. The vessels will provide commuter transportation for the port city of Antwerp, Belgium, connecting the center of Antwerp with the southern reaches of the city via the River Scheldt. Eventually, the routes will expand to connect to Antwerp’s northern end, too.
The project results from Damen’s 2013 investment in a composites shipbuilding facility in Antalya, Turkey, where the composites knowledge center joins three other Damen facilities to form a 538,196-square-foot shipyard in a boat-building tax-free zone. “When we first took over the composites factory, there were four people in the building. Now we have 100 employees including composites specialists, engineering project management and support, working in air-conditioned lamination production and material storage areas,” says Marko Paš, Damen’s business development manager for composites.
Damen has built more than 80 aluminum and steel passenger ferries, but this is its first water bus made from composite sandwich construction for the urban transportation market. Model sizes range from 52.6 to 78.9 feet long and accommodate 20 to 120 passengers. The vessel needed to meet several key production and operation objectives, including flexibility, streamlined and efficient manufacturing, passenger comfort, reduced fuel consumption and low cost per seat. That drove the decision to go with GFRP sandwich composites for the hulls, engine room, superstructure and deck.
The GFRP twin hulls reduce water displacement, lower resistance and contribute to speed, energy efficiency and safety. “We conducted testing to compare 5- to 6-millimeter aluminum hull plates with composite sandwich panels, and the composite panels outperformed the aluminum,” says Paš. “When the metal vessel hit floating objects such as debris, the aluminum skin was cut and the hull would take in water. With composite sandwich construction, even when the outer skin was penetrated, the closed-cell core absorbed quite a bit of energy, the inner skin stayed intact and water absorption remained localized.” This is a benefit for use in urban transportation settings, where floating objects are likely to be encountered.
Depending on the loads required and the length of span, the sandwich construction’s PVC foam core ranges from 20 to 40 millimeters thick with an average outer skin thickness of 3 millimeters and inner skin thickness of 2 millimeters. “The growth of the wind energy industry has made the supply of PVC core challenging, so we maintain relationships with both Diab International and Gurit to ensure quick delivery of the core,” Paš says.