The fatigue life of ship structures is typically based on deterministic methods in which underlying uncertainties are only implicitly taken into account and not explicitly reflected. Guidance for a probabilistic assessment is provided in class documents, but the methodology is too time consuming to apply in design practice. This paper proposes a novel approach based on DNV-CG-0129 to incorporate uncertainties and consequences explicitly. Using a probabilistic model, tailored deterministic FAT classes are derived to be applied in design practice. A tailored FAT class should be selected based on an acceptable probability of failure related to the severity of the consequences of a failure for the ship. Results show that tailored FAT classes are strongly dependent on the uncertainties provided as input when using the calculation method of DNV-CG-0129. This emphasizes the need for careful consideration and specification of the uncertainties. Furthermore, application of the First Order Reliability Method for a sensitivity study shows that the global model uncertainty is governing over other uncertainties considered in DNV-CG-0129. The proposed approach enables a low-effort and transparent probabilistic-based method, leading to optimized and improved designs due to reduction of overdimensioning in non-critical areas.