Notes on the Structural Analysis of Container Ships (3) ed the transfer function or the response amplitude operator (RAO), Y(f, t2). It can be approximated rather well by the strip method. An unpublished comparison of Germanischer Lloyd between the strip theory and model test shows good agreement concerning vertical, and horizontal shearing forces and moments as well as torsional moments at amidship. Results for an angle of encounter of 45° and for a Froude number of 0.212 are presented in Fig. 2. By structural analysis transfer functions for stresses can be determined from the transfer functions for moments and forces. Response of ship in irregular seaway Once the transfer functions are known, the response of the ship in the irregular seaway can be determined by statistical methods. A study of recordings of seaway effects such as moments or stresses reveals that their departure from their mean values are distributed approximately according to the Rayleigh distribution, Fig. 3. The probability that some given value, Xm, is being exceeded is therefore given by