Power prediction and fw

How do we determine the unknown weather factor?

Legislation on the Energy Efficiency Design Index (EEDI) requires the determination of a “weather factor” – fw – reflecting the percentage of its calm-water speed that a ship can maintain in Beaufort 6 and corresponding waves. The higher the fw value, the smaller the speed loss and the better the ship will perform in a seaway. But how do we determine this unknown fw factor, and how do we strike a balance between accuracy and costs?

As a member of the International Towing Tank Conference (ITTC) SSPA is actively involved in developing guidelines on fw and as an independent maritime consultant and established model testing basin we have the knowledge and tools required to realistically determine the “unknown weather factor”.