Australia’s warships and submarines are collectively the most complex, critical and expensive warfighting assets within Defence’s inventory. Asset managers make decisions where beneficial short-term effects may cause unforeseen long-term repercussions leading to increased life cycle costs, decreased (or lost) capability and reduced operational availability that affect the operations and maintenance profile across each usage and upkeep cycle. Predictive life cycle forecasting provides an objective and empirical method to quantify budgetary requirements based on estimated future effects to operational readiness and seaworthiness. The life cycle forecast is a key component of each vessel’s asset management plan and records the operations and maintenance profile across the asset’s service life by establishing requirements for products and services needed to support the vessel within the prescribed asset management system. Predictive life cycle forecasting initially begins with establishing a baseline life cycle model that amalgamates contiguous operational running periods and scheduled maintenance activities across multiple usage and upkeep cycles to provide a time-phased representation that projects expected costs, operational availability and capability baselines from commissioning to disposal. Variable phases, states & modes provide the means to adjust model parameters to probabilistically characterise options available to asset managers when evaluating and assessing various scenario outcomes. An interactive model can provide asset managers with immediate feedback based on options explored within the model. Using each vessel’s life cycle model, predictive life cycle fore-casting can provide a consistent and logical method for systematically updating as-set management plans. Robust and comprehensive predictive life cycle forecasting supports asset management decision-making to more accurately optimise warships’ and submarines’ availability, capability and affordability across the life cycle. As a fully scalable method, it can be applied to a single vessel, class of assets or to the collective fleet as a fundamental technique to support Fleet Life Cycle Management.