Bluenose project helps set the international standard for composite safety
Built in 1921, the Bluenose fishing and racing schooner was the fastest of its kind, an iconic symbol of craftsmanship and innovation. Since 2014, Damen Shipyards Group has been applying the same kind of pioneering spirit to a project that aims to dramatically improve the viability of composite hulls for larger vessels.
The Bluenose project, led by Marcel Elenbaas at Damen Schelde and comprising a team of research engineers from Damen Shipyards Gorinchem and Damen Schelde Naval Shipbuilding, takes inspiration from past innovation in a bid to develop effective new solutions. The overall objective of the project is to boost composite development within Damen beyond the class rules. In doing so, the project pioneers the design and construction of a new product and concurrently helps to develop standards governing the use of that product.
Shipbuilding is changing. Efficiency is critical, and structural materials make all the difference when it comes to performance. Vessels made of composite materials, rather than traditional steel, can be up to 30% lighter than comparable vessels, meaning fuel consumption and costs can be significantly lower. For Damen and other shipbuilders, composite materials are already a standard structural material in the construction of smaller ships such as fast ferries and sailing yachts up to a length of about 25 metres. The application of composite materials to larger vessels, however, is a different, and relatively unexplored, undertaking.
The loads of Damen’s composite commercial transport vessels are well understood and predictable, and the level of risk the vessels face in operation is relatively low. With greater scale comes greater complexity, and creating reliable composite hulls for larger boats raises different challenges in terms of stability and safety. In the Bluenose project, Damen researches ways to overcome these challenges and contribute to the creation of internationally recognised safety standards for larger composite-hulled vessels.
The project is comprehensive, requiring deep investigation into the properties of composite materials, their durability, and their response to the effects of vibration, heat and force. Safety is the most critical aspect of preparing these types of vessels for operation, as their vulnerability in the open ocean is much greater than that of vessels operating close to shore.
A significant area of attention is the behaviour of composite materials under typical stress scenarios such as wave-bending and slamming forces. As principal research engineer Don Hoogendoorn explains, this is a new area of research, “The tests we conducted found that the class bending moment under-predicts the measured wave bending moment of the composite, which means we needed to conduct a lot of analysis and produce revised predictions of this effect.” There is no margin for error in these scenarios, and careful analysis is required to formulate a fail-safe design.
Don and the team had a similar experience with the slamming tests. “When the composite was tested in slamming simulations,” says Don, “we found that its dynamic material properties differ from the static material properties, which indicates the need for a highly specialised testing process and a new set of class rules for larger composite vessels.”
The project has also found that class partial safety factors can’t be applied to the materials in this context, and therefore one of the project milestones must be to create a framework of partial safety factors for a first principles-based composite design. Whereas class partial safety factors are common practice in other industries such as aerospace, the difference in dimensions between these applications means a new set of safety factors must be investigated and determined. The project has designed a new test matrix in partnership with Bureau Veritas that could lead to the creation of a new industry test matrix, which could eventually result in lighter ship design.
The project team took pains to ensure a specific focus of the work packages included fire safety of large composite vessels. “When it comes to fire safety assurance,” explains technical specialist in composite structures Cedric Verhaeghe, “vessels operating close to shore can be assisted and rescued, and therefore face a lower fire safety risk, whereas ocean-bound vessels don’t have the same support option.” The Bluenose project therefore includes rigorous fire safety testing procedures, and has created a quantitative risk-based design approach to fire safety assurance for large composite vessels. Cedric believes this could play a pivotal role in future standards development; “Fire safety regulations for these vessels are relatively new, and Damen hopes to contribute to an update to the current international regulations next year,” he says.
In pursuing all this research, the Bluenose project created a database of tests that can contribute to the formation of new industry standards. Damen, in partnership with Bureau Veritas, is ready to propose rule making and approach guidelines as part of the creation of these new standards. The partnership also shares Bluenose project findings with the RAMSSES project to aid in the progression of research into advanced material solutions, allowing the EU to directly benefit from this research.
Overall, the Bluenose project comprises unique yet complementary work packages:
• Wave bending moment
• Partial Safety Factors
• First principle structural design
• Production technology
• Fire safe design
• Quality assurance
• Sound and vibration
• Thermal insulation
As the work enters its final six months, all work packages bar two (First principle structural design and Fire safe design) are complete. Damen Shipyards Gorinchem is in the process of scaling up its structural design investigations on the composite material, increasing the scale from 40-metre vessels upwards.
Production technology shows very promising results, based on the production of a large hull with the dimensions of 80 metres in length by 6 metres in height. Regarding the wider ramifications of this work, Cedric is very positive. “We’ve provided this knowledge to be integrated in the RAMSSES project,” he says, “and we expect it to lead into demonstrating the infusion of a hull in early 2020 to establish the quality and strength that can be achieved by applying composites through this process.” Given the lack of class rules for the structural performance of large ships, this research can add to the knowledge base to help develop class rules for large ships in this category.
While the full report of the Bluenose project isn’t yet available, more information about the RAMSSES project is online, including Damen’s contribution regarding the design of a complete composite vessel fulfilling SOLAS requirements and class rules. More innovative Damen projects are also listed online.