Objectives  This paper aims to study the fatigue damage problem of large ship prone to springing effect.

  Methods  The test result in two generation 400 000 DWT very large ore carrier (VLOC) are compared based on ship model test method, and the relation of sea states and fatigue including hull girder springing are analyzed. According to the recursion method, a classical sea state is selected from a series of model test sea states.

  Results  The results show that the fatigue damage magnification effect has a trend relationship with significant wave height and encounter period. The concept of "dominant sea state" is proposed based on the recurrence method, and the expression of fatigue damage magnification factor is improved. The springing effect varies significantly according to different sea states, and the fatigue damage magnification effect of springing increases very rapidly as significant wave height and encounter period decrease.

  Conclusions  Replacing multiple model test loading conditions with dominant sea state could allow relatively accurate fatigue damage magnification factor to be ascertained rapidly. As such, this paper can provide references during the initial design period.