scope:

Scope and Overview of These Guidance Notes

These Guidance Notes provide the analysis procedures of air gap assessment for semi-submersibles based on either the linear analysis or the second order analysis. The theoretical background of these methods is introduced with critical parameters highlighted. Guidance is also provided on the definition of the horizontal wave impact load and the strength assessment methods for those local structural members on peripheral sides of the upper structure subject to wave impact loads.

Section 2 describes the three-dimensional diffraction-radiation analysis used to calculate vessel motions. Both linear frequency domain and nonlinear time domain methods are addressed.

Section 3 discusses the free surface elevation induced by wave-structure interaction and addresses the wave asymmetry and wave run-up phenomenon.

Section 4 presents the linear air gap analysis procedures in frequency domain.

Section 5 demonstrates the second order air gap analysis procedures in time domain.

Section 6 presents the horizontal wave impact loads and local structural strength assessment methods for the peripheral sides of the upper structure of semi-submersibles when there are negative air gaps.