Hm&e systems is a research domain and engineering discipline focused on the comprehensive study, design, analysis, and lifecycle management of the integrated hull, mechanical, and electrical systems critical to the operation and sustainment of complex maritime platforms and associated infrastructure. This field investigates the architecture, performance, control, maintenance, and cyber resilience of machinery, propulsion, power generation and distribution, structural components, environmental controls, and their interconnected control systems and networks, emphasizing reliability, maintainability, and operational readiness in demanding environments.