At MIT Sea Grant Design Lab, we develop variable-fidelity models from first principles for a variety of engineering and scientific applications. We solve these models using computational methods that we develop. Some of the research we will highlight include system-level thermal modeling of all electric ships, high-fidelity simulations of thermal components aboard naval ships, and developing computational methods to predict rare events such as extreme waves. We also develop algorithms that blend in information from multiple sources with different levels of fidelity to predict the response of the system. The outcome of our modeling and computational capabilities allows us to understand, analyze and design engineering systems.