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Maritime Fusion (YC W25) — Fusion reactors for ships

Maritime Fusion is building fusion reactors for ships and off grid energy markets. En route on this endeavor we’re commercializing High Temperature Superconducting (HTS) cable technology for power distribution while advancing the physics basis of our HTS tokamak to decarbonize global shipping.

Maritime Fusion is a Y Combinator company in the Winter 2025 batch. Its directory entry describes it as: Fusion reactors for ships. The founders listed are Justin Cohen (Founder/CEO), Jason Kaufmann (Founder/CTO) (Y Combinator directory entry, February 14, 2025).

6 more companies from YC Winter 2025 ↓

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Maritime Fusion

New accelerator entry · 2025-02-14 · the record

Winter 2025
batch
6
people
Early
stage
United States of America
region
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What the record says

BatchWinter 2025
Announced2025-02-14
StageEarly
StatusActive
Team size6
IndustryIndustrials
Sub-industryIndustrials -> Energy
SectorsFusion Energy, Hard Tech, Energy
RegionsUnited States of America, America / Canada
BasedSan Francisco, CA, USA
HiringYes
Sitehttps://maritimefusion.com

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Also in YC Winter 2025

Same batch, Industrials first.

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In their words

Maritime Fusion is building fusion reactors for ships and off grid energy markets. En route on this endeavor we’re commercializing High Temperature Superconducting (HTS) cable technology for power distribution while advancing the physics basis of our HTS tokamak to decarbonize global shipping. Breakeven fusion is coming soon, but the first-of-a-kind (FOAK) reactors will be costly, high maintenance, and have low capacity factors, leading to 5–10x higher electricity cost on the grid. Maritime Fusion is pursuing the most widely accepted approach to fusion, the tokamak, but specifically designed for the marine environment where the challenges that arise between breakeven and a commercially viable energy source are alleviated. The market we're targeting requires 15x less power, lower up-time, and costs the same as alternative fuels but without any emissions. Since fusion does not use highly radioactive fuels or materials – unlike fission – we sidestep the vast majority of regulatory challenges and safety risks associated with nuclear energy. Our team brings over a decade of industry and research experience in plasma physics, nuclear engineering, and electrical engineering with backgrounds at SpaceX, Tesla, Columbia University, and University of Pennsylvania.

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Maritime Fusion: Accepted into Y Combinator Winter 2025
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Permanent URL: https://mentionfox.com/funding/yc-maritime-fusion
Last updated 2026-10-20
Primary record: Y Combinator directory entry
Maritime Fusion (YC W25) — Fusion reactors for ships. MentionFox, 2026-10-20. https://mentionfox.com/funding/yc-maritime-fusion