A Simple Method for Predicting the Grounding Strength of Ships

Abstract

Although the destructive effects of grounding accidents are understood, very few tools are available that can be used by designers to evaluate a ship's strength in grounding accidents. This paper proposes a simple method to predict the strength of a ship's bottom during the process of grounding. A ship's hull is characterized by structural members that are periodically arranged along the ship length. As a result, the internal resistance force developed during grounding is in a sense periodic in the longitudinal direction. For the main structural members of the ship bottom, the following four primary failure modes are considered in this paper: the stretching failure of transverse structures, denting, tearing and concertina tearing failure of bottom plates. The calculation formulas for these identified failure modes are assembled to construct the prediction method for bottom strength. The proposed method is verified by checking the predictions against a series of large-scale grounding experiments and an actual grounding accident. The attractiveness of the method developed is that it makes possible the prediction of the strength of a ship hull in the event of grounding using hand calculation.