Solico Engineers the Flax Fibre Eagle 46 for Leonardo Yachts

The Leonardo Yachts Eagle 46 is the latest addition to the company’s Eagle line of modern classic daysailers. Solico has engineered the new yacht, its first large natural fibre composite structure, which will be built by Dutch tooling and custom boat specialist Paul Dijkstra Composites. Leonardo Yachts decision to commission the engineering of the new Hoek designed 46 with sustainable flax fibres is a testament to the company’s commitment to reduce the environmental impact of the yachts that it builds.

Solico's scope of work for the Leonardo Yachts Eagle 46 encompasses comprehensive FEA (Finite Element Analysis) engineering of the entire boat. This work includes crucial aspects such as the hull-keel connection, mast-deck, and stay-deck connections. Additionally, Solico is also responsible for the verification and engineering of the metal keel. The initial laminate schedules were defined by the builder, with Solico providing further optimization and reinforcements as necessary to meet the project's requirements and the ISO 12215 standards. Moreover, Solico has made modifications to the initial structural arrangement provided by the builder to enhance the overall design.

Before the engineering process began, Solico coordinated discussions between Leonardo Yachts, the builder and flax fibre reinforcement specialists Bcomp to define the flax materials that would be used. To reduce waste, simplify inventory and optimize project costs, a single flax fibre reinforcement was selected for the new Eagle 46. Bcomp ampliTex™ 5042, a 500gsm 4x4 twill weave fabric, supplied by Gurit in prepreg format using the SE75 resin system, was chosen for the new yacht and will be combined with a recyclable PET foam core in the sandwich construction hull and deck.

“When we started this project, we looked for accurate mechanical data for flax reinforcements and working with Paolo Dassi, Marine and Industry Manager at Bcomp, we were able to quickly confirm the key engineering design data points for both dry ampliTex™ woven fabrics and the final epoxy prepreg laminates,” said Matej Prevc, Senior Lead Engineer for the project. “Before production begins, we will also test sample laminates provided by the builder in our own laboratory at Solico, validating the real life panel properties with our engineering model.”

Flax fibres are becoming increasingly common in yacht construction as owners and designers look to lessen the environmental impact of marine composite structures. Bcomp states that its flax fibres are CO2 neutral over their life cycle and that parts made using its flax reinforcements can have a CO2 footprint 85% lower than that of thin-walled monolithic carbon fibre parts with equal stiffness and weight.

Bcomp also worked directly with the builder Paul Dijkstra, supporting the shipyard with additional recommendations for working with flax fibres. The deep and detailed understanding that their engineering team has of their ampliTex™ reinforcements in a wide range of applications allows them to provide invaluable technical support to builders and designers. As a result, in this case, glass layers have been incorporated on the water side of the hull for enhanced durability, while the inside of the hull will utilize a UV resistant topcoat instead.

Solico’s engineering work for the yacht is now complete. Hull number 1 of the new design is being built with carbon prepreg and Corecell™ foam with the full flax version currently planned to join the range soon.