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Maritime Fusion

4 open
San Francisco, California, United StatesFounded 20246+ employeesSeed raisedSeedPrivate
Last round: seed · $4.5M · Nov 2025(3 rounds total)
Fusion reactors for ships
Backed by(6 investors)
Y CombinatorTrucks Venture CapitalAlumni VenturesAera VCPaul GrahamNetwork.VC

Maritime Fusion develops fusion-based power systems intended for marine and remote-energy operations. Its core product concept features compact tokamak reactors that use high-temperature superconducting magnets to generate continuous power for vessel propulsion and onboard electricity. The company also creates superconducting cable assemblies for power transmission within fusion systems and marine electrical networks.

YC W25

About the Company

Maritime Fusion is building fusion reactors for ships. We’re laser focused on designing, optimizing, and manufacturing HTS tokamaks to decarbonize global shipping and deliver operational energy and HTS technology to defense customers. Since participating in the world's leading startup accelerator, Y Combinator, we’ve moved quickly to plot the most pragmatic path to getting the First of a Kind (FOAK) fusion reactors out in the world in an application most primed to benefit from recent advances in High Temperature Superconducting (HTS) magnet technology. Our founding team brings a unique blend of hands-on engineering experience from Tesla and SpaceX, combined with deep academic expertise in plasma physics and fusion energy technology from academia and industry.

Tech Stack

Plasma physics (equilibrium, current drive, turbulence, shaping, etc) Structural and magnet engineering (10T toroidal field magnets) Systems integration (vacuum vessel + beam ports + diagnostics + blanket tank + fueling + maintenance operations) Feedback control (disruption avoidance and prediction, quench detection) auxiliary systems (magnet cryogenic system, RF gyrotrons + power supplies, molten salt system and heat exchanger)

Founders

Justin Cohen
Justin Cohen

Nuclear engineer and plasma physicist working on fusion reactors for defense and commercial shipping applications. Previously Tesla, SpaceX, Columbia University, Princeton Plasma Physics Laboratory, NC State.

Jason Kaufmann
Jason Kaufmann

I'm a hardware engineer with a passion for building cool electronics and systems. With a background in physics and computer engineering from Penn, I've worked on everything from AI hardware at Tesla to power systems for rockets at SpaceX. Currently focused on making a fusion reactor for ships.

Ready to start your space career at Maritime Fusion?

Shipping like we're funded. We're not. No affiliation.

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