Floating Breakwater Ljansbruket
- Ljansbruket - Norway
FDN Group conducted a comprehensive feasibility study for the development of a new leisure marina in the Oslo region. The project involved detailed engineering and design of a floating breakwater system capable of providing safe and effective wave protection. The study included evaluating the best marina layout, sizing floating elements for damping waves up to four metres, and assessing hydrodynamic stability, anchorage, and flexible rubber connectors. This innovative design aimed to safeguard the marina while enhancing the waterfront experience in Oslo.
Project Description
The Ljansbruket project focuses on designing 600 metres of floating breakwater in Oslo Fjord, in water depths reaching 80 metres. The system is engineered to protect the proposed leisure marina from waves up to four metres, ensuring a calm and secure environment for boats and visitors. The study involved a site visit requested by the Oslo Commune to validate local conditions and optimize the marina layout.
Challenges of the Project
The primary challenge was to develop a floating breakwater that can withstand high waves while remaining stable in deep waters. Designing flexible connections and selecting the appropriate anchorage type were critical to ensure the breakwater’s durability. Additionally, the complex fjord conditions required precise hydrodynamic assessments to guarantee effective wave damping and long-term reliability.
Sustainability
Sustainability was central to the design. The floating breakwater minimizes environmental impact by avoiding large-scale seabed interventions. Materials and components were selected for durability and minimal maintenance, ensuring the system provides long-term protection without compromising the marine ecosystem.
Innovation & Technology
The project leverages advanced engineering techniques to create a floating structure capable of adapting to dynamic wave conditions. Hydrodynamic simulations informed the optimal sizing of floating elements, while flexible rubber connectors allowed for movement without structural stress. The design integrates state-of-the-art anchorage solutions to maintain stability in deep water.
The new breakwater will extend capacity of the current marina, and will protect berthed ships and boats. The projected capacity is around 450 berthing places for small-sized vessels. The expected total length of the breakwater is approximately 640m. There will be two main floating bodies, which would consist of smaller elements with a length of 16 – 30m. The width of the pontoons is around 10m. The width is relatively large due to need for a proper damping of the waves by 80% and for a comfortable use. The floating concrete pontoons offer a storage capacity inside the hollow body. The concept of the floating breakwater has been chosen because of large water depth at the location (varying between 10 – 100m) and strict environmental requirements. The floating harbour is intended to be built from standard concrete, but also high-strength concrete HSC seems to be a very convenient solution.
FDN’s Contribution
FDN Group led the feasibility study, concept design, and engineering analysis. We determined the most efficient marina layout and breakwater configuration, calculated wave loading, and defined the specifications for floating elements, connectors, and anchoring. Our expertise ensured the project meets safety, performance, and sustainability standards while addressing the Oslo Commune’s requirements.
Partners
This study was conducted in collaboration with local authorities Oslo Commune and engineering consultants to ensure compliance with regional regulations and to align with community objectives. FDN Group’s integrated approach facilitated a seamless collaboration between stakeholders and optimized the project outcome.