On the prediction of the added resistance of large ships in representative seaways

The importance of the sufficiently accurate prediction of the added resistance and powering of large ships in representative seaways is discussed. We introduce an updated empirical formula that may be used by engineers for the fast estimation of the added resistance of ships in waves and validate this formula for ships with L-PP > 250 m operating in realistic sea conditions. The importance of the accurate prediction of added resistance of large ships is demonstrated by numerical and experimental studies on both full and fine hull forms. It is shown that for large ships sailing in representative seaways, properly quantifying the spectral contribution of the added resistance in the region of lambda/L-PP approximate to 0.1 similar to 0.5 is of paramount importance and further studies are necessary to resolve this issue for large ships. This also leads to a critical discussion about the ITTC recommended experimental procedure, when assessing the overall seakeeping performance of large size ships in representative seaways.