Senior Mechanical Engineer (Primary Structures)

About Endurance Endurance is building the world's first modular subsea geothermal power plants, converting vast thermal resources under the ocean into gigawatts of baseload power. Backed by Founders Fund, Felicis, First Round Capital, and Point72 Ventures, our founding team includes veterans from SpaceX, Helion, Blue Origin, and Apple. We have completed multiple deep-ocean deployments to subsea volcanoes and are launching a long-term demonstration project this fall. By leveraging modular design, manufacturing scale, efficient drilling, and latent cooling on the seafloor, we are pioneering a new category of energy that outperforms traditional sources on environmental impact, deployment speed, and cost. The Role The primary structure is the plant. It carries the hot loop, the power electronics, and the connection to the well; it survives the lift, the splash zone, the transit, and the landing on an active hydrothermal field 1-3 km down; and then it stays there for years in seawater at 100-300 bar. We design, build, test, and deploy it. In this role you will focus on the plant's load-bearing hardware: frames and skids, foundations and seafloor landing systems, lifting and deployment hardware, mooring and anchoring interfaces, and the pressure housings and pressure-tolerant structures that mount to the frame. You will share that scope with a few other engineers, and specific structures will be yours end to end. We avoid pressure vessels where we can through compensated and pressure-tolerant design, but where we cannot, you will design and analyze them. We use ASME, DNV, and API as references and build our own qualification basis through test. Your First Year Help deliver the primary structure for our first commercial system, the first subsea geothermal plant to put power on a grid: designed, analyzed, built, qualified, lifted, and landed on the seafloor. The load cases and qualification basis you help establish carry forward to every plant that follows. How We Work Our mechanical engineering team is a small group of senior and principal engineers who split the plant's hardware between them. Each engineer owns their hardware end to end: requirements, design, drawings, build, test, and deployment. Principal engineers own the plant architecture, and you will be part of those decisions. We are looking for people who have built hardware, debugged it in the lab or the field, and want to own the result. Responsibilities

• Own specific elements of the primary structure end to end: frames, foundations and landing systems, lifting and deployment hardware, or pressure housings

• Define structural load cases from first principles: lift through the splash zone, transit, landing on irregular seafloor, thermal expansion of the hot loop, hydrodynamic loads, and long-duration fatigue and corrosion

• Size structures with hand calculations, then prove them with FEA: static, fatigue, buckling, external-pressure collapse, and thermal

• Design pressure-tolerant and pressure-compensated structures where possible; design and analyze pressure housings where required

• Design lifting, rigging, deployment, and recovery hardware and the interfaces to vessels, cranes, and ROVs

• Select materials and corrosion strategies for multi-year seawater exposure: cathodic protection, coatings, galvanic isolation, titanium, duplex stainless, and composites

• Own weld design and fabrication for your structures and work directly with fabricators on procedures, inspection, and tolerances

• Build and test development articles, then qualify full structures: hydrostatic, external-pressure, fatigue, and thermal cycling

• Lead root-cause investigations on structural and housing failures and implement corrective actions

• Define interfaces with the fluid components, electromechanical hardware, and well connection owned by your peers

• Contribute to plant-level architecture decisions alongside our principal engineers

• Create detailed 3D CAD models, drawings, and tolerance stacks for large assemblies Basic Qualifications

• Bachelor's degree in mechanical, aerospace, structural, or ocean engineering, or a related engineering discipline

• 6+ years of professional experience designing and analyzing load-bearing structures for demanding environments

• Ownership of at least one large structure from design through fabrication and fielded use Preferred Skills and Experience

• Experience designing primary structures for subsea or offshore systems, submarines or naval vessels, launch vehicles or aircraft, or heavy industrial equipment

• Experience designing or analyzing pressure vessels, especially for external pressure, and familiarity with ASME VIII, DNV, or API

• Strong fundamentals in solid mechanics, structural dynamics, and fatigue; comfortable sizing a structure by hand before confirming it with FEA

• Fabrication fluency: weld joint design, allowables, NDT and inspection, and tolerancing of large weldments

• Experience designing lifting and rigging hardware or working with marine operations

• Experience building test articles and running structural qualification tests

• Experience at a small or fast-moving hardware organization, where you had to make good engineering decisions with incomplete information and limited resources

• A track record of taking on increasing responsibility and delivering something difficult early in your career

• Experience on an engineering competition team (Formula SAE, Baja SAE, RoboSub, rocketry, or similar) or an equivalent self-directed hardware project Compensation, Benefits, & Perks As a pre-revenue startup, Endurance Energy offers competitive base salaries and generous equity packages for full-time employees. Final base salary will be determined by an array of factors including internal equity, job-related knowledge, skills, and work experience. A key aspect of our compensation philosophy is that value creation should be aligned with rewards. Right now this means equity is a significant portion of every full-time employee's compensation. As the company matures, there will be continued evolution and changes to the total rewards and total compensation package. What will always be true is that if we win, we win together. Equity is granted to every full-time employee as a meaningful piece of ownership. We believe the people building the company should share directly in the value they create. In addition to a competitive base salary and equity, employees will receive all of our other great benefits and perks, including:

• Benefits: Health, Dental, and Vision insurance coverage

• Time Away: Flexible PTO including 12 paid company holidays

• Global Fieldwork: Travel to fascinating deployment sites along oceanic ridges in locations like the Pacific Northwest, Hawaii, Iceland, Japan, New Zealand, and the Azores

• Hands-on Experience: Participate in sea trials and deployment operations in partnership with leading oceanographic institutions

• Cutting-edge Development: Work with technology that spans high-power electronics, marine systems, and clean energy

• Impactful Work: Help solve one of the world's most pressing challenges

• Dive Certification: Company-sponsored recreational dive certification

• Other Perks: Access to the company boat, free meals and snacks, and the list goes on!

If you’re selected for consideration, a recruiter will be able to discuss in greater detail.