Objective As the ship unsinkability calculation method based on two-dimensional slicing has such problems as limited modeling ability and insufficient applicability to complex ship types, this study proposes a panel method-based ship unsinkability calculation technique based on a three-dimensional fully-appended ship model.

Methods  Adopting a discrete three-dimensional triangle panel model, the normal directions of the ship panels and damaged compartment are set opposite each other so that their buoyancy cancels each other out and causes buoyancy loss. A watershed transformation algorithm is used to achieve the matching of wetted surface panels in any floating state. Based on the Gaussian formula, the integration of displacement volume is transformed into the integration of wetted surface area, and the displacement volume and water plane elements are further solved through the panel projection integration method. Newton−Raphson method is then used to calculate the floating state of the damaged ship and conduct an unsinkability evaluation.

Results Taking the Wigley numerical ship model and standard ONR (Office of Naval Research) tumblehome (ONRT) ship model as examples, the accuracy of the algorithm is verified and an unsinkability evaluation is conducted for the ONRT fully-appended ship model. Conclusion The calculation example shows that the proposed method has reliable calculation accuracy, strong applicability to complex ship types and practical engineering value.