ABOUT ARSENALS AI Arsenals AI builds autonomous underwater systems to transform the future of democratic navies. We design and manufacture full-stack products—embedded electronics, autonomy software, and production hardware—built for harsh, real-world environments. We're an early team. If you join, you will shape the technical foundations, culture, and velocity of the company. ABOUT THE ROLE As a Founding Hardware Engineer, you will own the physical heart of our systems and push them from prototype to field-ready, sea-proven products. This is not a narrow role. You will architect, design, prototype, test, debug, integrate, document, and iterate—often with incomplete information and aggressive timelines. You will move between CAD, the electronics bench, the machine shop, and the water, sometimes in the same week. As one of the company's first employees, you will play a major role in shaping the company and building and leading major projects that operate like "companies within the company". We are looking for the best engineers who are committed, passionate about the mission of transforming democratic navies, and thrilled by the major technical challenges ahead. RESPONSIBILITIES - Own end-to-end development of core hardware subsystems: mechanical structures, pressure hulls, propulsion, electronics integration, and payload interfaces. - Design, prototype, and validate innovative solutions that no one has ever done—from first sketch to sea trials. - Design for the underwater environment: pressure, corrosion, sealing, buoyancy, thermal management, and shock/vibration. - Build the test infrastructure (benches, jigs, pressure/environmental testing, instrumentation) to validate hardware fast and rigorously. - Take designs from prototype to small-series production: DFM/DFA, supplier selection, sourcing, quality control, and assembly processes. - Build and lead a future team of engineers (hiring, onboarding, setting standards, and owning delivery). CANDIDATE REQUIREMENTS (MUST-HAVE) - Graduate from a top engineering school or university. - 7+ years of hardware engineering experience (mechanical, mechatronics, electromechanical systems) with evidence of shipped or field-tested hardware. - Fast prototyper: able to design, build, test, and iterate quickly with real-world feedback—comfortable with hands-on fabrication (machining, 3D printing, composites, wiring). - Fluent in CAD (e.g., SolidWorks, Fusion 360, Onshape) and mechanical simulation/analysis (FEA, structural, thermal). - Strong systems thinking: reason about system-level trade-offs (mass, cost, reliability, manufacturability, maintainability) across mechanical, electrical, and software boundaries. - Own a subsystem end-to-end—from requirements and architecture to validated, documented, production-ready hardware—and be eager to learn in a fast-evolving environment. - Solutions-first mindset: you look for ways to make things work, not reasons they won't. PREFERRED SKILLS (NICE-TO-HAVE) - Marine or underwater hardware experience: pressure vessels, subsea connectors, sealing (O-rings, penetrators), anti-corrosion design, buoyancy and trim. - Propulsion and actuation experience: thrusters, motors (BLDC), ESCs, control surfaces, gearboxes. - Electronics engineering experience: PCB design and bring-up, power electronics, battery systems (Li-ion pack design, BMS, safety), harness design. - Familiarity with embedded systems and how hardware choices affect software (sensors, buses like CAN/UART/SPI/I2C, EMI/EMC considerations). - Experience with hydrodynamics or fluid dynamics (CFD, hull/fairing design, drag and stability analysis). - Experience taking hardware from prototype to production: DFM/DFA, supplier and contract-manufacturer management, BOM and cost management, quality processes. - Experience with environmental qualification and testing (pressure, ingress, thermal, shock, vibration, salt fog) and relevant standards. - Experience operating hardware in harsh environments (marine, aerospace, automotive, defense). PRACTICAL DETAILS - Location: Paris (with hands-on prototyping, testing, and weekly travel for integration/sea trials) - Contract: full-time