Oil and gas are still the world’s most common source of energy supply. About 90 countries around the world are producing oil at the moment, although a few major producers account for the bulk of world output. By increasing new oil and gas discoveries in deep water areas, demand for floating offshore platforms is in increase. Among floating offshore platforms Floating Production Storage and Offloading systems (FPSOs) are more popular than the other types because of their great advantages such as integral storage and offloading, low capital cost, re-usability and shorter lead time particularly for conversion. The content of this book is focused on the development of a response-based design method for turret-moored FPSOs subjected to arbitrary environmental loads. The method developed is based on ANN and the use of long-term met-ocean data.