Session: 09-02-06: Wind and Wave Energy: Moorings

Submission Number: 157507

Mooring Design Under Tropical Cyclones 

Mooring tension response is dependent on various environmental conditions, such as significant wave height, wave period, wind speed, and their directions. An efficient and robust design of mooring lines requires an accurate estimation of joint extreme of environmental variables represented by long-term and short-term characteristics. However, in tropical cyclone regions, the limitation of sample size make the joint extremes challenging to model. Uncertainty in the modeling process leads to conservative design conditions. Especially, the modelling process of dependency structures among extreme variables can lead to large redundancy when we need to assume simultaneous occurrence of extreme values for every variable.

In the presentation, we present a method for estimating extreme mooring tension utilizing multivariate time series generated from MSTM-TE methods (Sando et al, 2024). The model is based on extreme conditional models and spatial inference. The model describing the dependency structure of environmental condition during the tropical cyclone event provides a method for efficient estimation of extreme response per event.

We conduct a case study on mooring system design for a floating offshore wind turbine located near Japan, a region that is hit by typhoons. We compare the proposed approach to existing methods for addressing extreme mooring tension and demonstrate how the methods compare in terms of bias and variance.

Presenting Author: Ryota Wada The University of Tokyo

Presenting Author Biography: Associate Professor at the University of Tokyo. After recieving his PhD at the University of Tokyo, he has conducted research in the field of Ocean Engineering with focus on extreme statistics and data-driven modelling.