Bias in estimates of extreme significant wave heights for the design of ship structures caused by neglecting within-year wave climate variability

ABSTRACT

The effect of within-year wave climate variability on the predicted extreme significant wave heights for the design of ship structures is examined. The significant wave height data is taken from ERA 5 database along frequent shipping routes. Monthly and annual extreme significant wave heights are extracted, and Gumbel distributions are fitted, respectively, using Maximum Likelihood Estimation. Monthly extreme wave heights are then combined, using the method proposed by Carter and Challenor [(1981). Estimating return values of environmental parameters. Q J R Metereol Soc. 107(451):259–266], to account for the effect of intra-annual climate variability. Long-term extreme values by two methods are compared for individual locations and shipping routes. Consequences on the extreme wave bending moments are explored, comparing the results to IACS rules. It was found that neglecting within-year wave climate variability leads to the underestimation of extreme significant wave heights and wave bending moments by up to 10 %. .

KEYWORDS:

• Extreme significant wave heights
• seasonal variability
• monthly and annual extremes
• Gumbel distribution
• reliability-based design

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work has been fully supported by Croatian Science Foundation [Project lP-2019-04-2085].