# Propeller: Catalyzing the Ocean-Climate Tech Revolution
Propeller is a Boston-based climate-tech venture fund dedicated to investing in and building ocean-climate companies that leverage science and technology to address the climate crisis.[3] Founded by former HubSpot CEO Brian Halligan alongside oceanographer Dr. Julie Pullen and other seasoned operators, Propeller represents a deliberate bet that the ocean—covering 71% of the planet and holding tremendous potential for carbon storage—has been dramatically underinvested in the climate-tech ecosystem.[2][4] The firm closed its inaugural $100 million fund in 2022 and subsequently raised an additional $117 million, deploying capital across 14 portfolio companies with check sizes ranging from $500,000 to $2 million.[1][2] What distinguishes Propeller is not just its capital, but its conviction that ocean-climate innovation represents one of the most significant yet overlooked opportunities in climate technology—a sector that received less than 1% of all climate-tech venture funding as of 2021, despite the ocean's outsized importance to global emissions reduction and carbon sequestration.[4]
High-Level Overview
Mission and Investment Philosophy
Propeller's core mission is to accelerate science-led solutions that leverage the ocean to mitigate climate change. The firm operates with a deliberate thesis: you cannot reach net zero without the ocean.[5] Rather than spreading capital thinly across the climate-tech landscape, Propeller has chosen to go deep in one area—becoming what managing partner Rodrigo Prudencio describes as "a magnet for entrepreneurs" in ocean-climate innovation.[1] This focused approach reflects a belief that concentrated expertise and network effects create better returns and greater impact than generalist climate investing.
The firm invests primarily in pre-seed and seed-stage companies, targeting transformational leaders building at the ocean-climate nexus across massive markets.[6] Propeller explicitly refuses capital from oil companies, signaling a commitment to mission alignment over maximum capital raising.[2] The firm's investment philosophy emphasizes scientific rigor—partnerships with Woods Hole Oceanographic Institution (WHOI) provide direct access to cutting-edge research, IP, and the brightest minds in ocean science, ensuring that portfolio companies are built on sound scientific foundations.[2][4]
Key Investment Sectors
Propeller organizes its portfolio across three core thematic areas:[6]
Ocean Carbon focuses on marine carbon dioxide removal (mCDR) technologies, blue carbon methodologies, and measurement, reporting, and verification (MRV) systems. Portfolio companies in this space include Ebb Carbon (electrochemistry-based CO2 removal from seawater), CarbonRun (river carbon removal), Aquatic Labs (ocean sensor technology), Coastal Carbon (ocean imaging), and Rewind (ocean carbon removal).[1]
Industrials encompasses energy, shipping, transportation, automation, robotics, surveying, inspection, insurance, and materials—including adaptation and dual-use applications that improve operational efficiency in ocean-dependent industries.
Organics targets innovation in food, feed, fertilizer, and aquaculture, recognizing that the ocean provides primary protein to nearly one billion people daily and represents a critical frontier for sustainable food production.[4]
Origin Story
Propeller emerged from a specific realization: despite the ocean's centrality to climate solutions, venture capital had systematically overlooked ocean-climate innovation. Brian Halligan, who built HubSpot into a multi-billion-dollar software company, encountered ocean scientists who were deeply optimistic about technological solutions to climate change. That optimism, combined with the stark funding gap, motivated him to launch Propeller in 2022.[5]
The founding team brought complementary expertise. Halligan brought operational excellence and capital-raising credibility from his HubSpot tenure. Dr. Julie Pullen contributed deep oceanographic and climate science credentials. Partner Reece Pacheco brought entrepreneurial experience (having sold a startup to Samsung) and connections to the World Surf League, grounding the firm in real-world ocean communities. The team also recruited entrepreneurs-in-residence, including Nike alum John Gillis and three veterans from Halligan's HubSpot days, embedding operational support into the fund's DNA from inception.[2]
The partnership with Woods Hole Oceanographic Institution was foundational to Propeller's identity. Rather than operating as a typical VC fund, Propeller formalized a multi-year partnership with WHOI, one of the world's leading ocean research institutions, backed by the U.S. Departments of Defense and Energy, MIT, and the Chinese Academy of Sciences.[2][7] This structure gave Propeller something few climate VCs possess: direct access to peer-reviewed science, emerging IP, and a network of world-class researchers who could validate and guide portfolio company development.
Core Differentiators
Specialized Expertise and Scientific Rigor
Unlike generalist climate VCs, Propeller has built institutional knowledge specifically around ocean-climate innovation. The firm's partnership with WHOI is not merely a marketing arrangement—it provides access to the intellectual infrastructure that validates investment theses and helps portfolio companies navigate complex scientific and regulatory landscapes. This is particularly valuable in ocean carbon removal, where methodological rigor and measurement accuracy directly determine commercial viability and climate impact.
Concentrated Portfolio Strategy
Propeller targets backing 30-40 startups from its fund, a deliberate choice to maintain depth rather than breadth.[1] This concentration allows the firm to provide meaningful operational support, network introductions, and strategic guidance to each portfolio company. The firm's check sizes ($500K-$2M) are calibrated to early-stage companies that need capital but also need hands-on support to navigate the technical and regulatory complexities of ocean-climate innovation.
Mission Alignment and Capital Discipline
Propeller's explicit refusal to accept capital from oil companies signals a commitment to mission integrity that resonates with founders and limited partners alike.[2] In an era where climate-washing has become endemic, this stance provides credibility. The firm's focus on science-led solutions—rather than speculative bets on unproven technologies—also differentiates it from more hype-driven climate VCs.
Operational Support Infrastructure
The firm embeds entrepreneurs-in-residence and leverages the WHOI partnership to provide portfolio companies with technical mentorship, regulatory guidance, and access to research infrastructure. This goes beyond typical VC support; it reflects a recognition that ocean-climate startups often need scientific validation and regulatory navigation as much as they need capital.
Role in the Broader Tech Landscape
Riding the Blue Economy Wave
Propeller is positioned at the intersection of three powerful trends: the acceleration of climate-tech investment, the emergence of the "blue economy" (estimated at $2.5 trillion globally), and growing government focus on ocean-based climate solutions.[4][5] The U.S. federal government's Ocean Climate Action Plan, released in 2023, explicitly prioritizes ocean-based emissions elimination and nature-based solutions, while the Department of Commerce and NOAA have allocated $60 million through the Ocean-based Climate Resilience Accelerators program.[5] These policy tailwinds create a favorable environment for ocean-climate startups.
Correcting a Massive Capital Allocation Inefficiency
Despite the ocean covering 71% of the planet and holding critical potential for carbon sequestration, ocean-climate tech received less than 3% of climate-tech investment as of recent years.[5] Propeller is attempting to correct this allocation inefficiency. The firm's thesis—that ocean-based solutions are essential to reaching net zero—is gaining traction among institutional investors, governments, and corporations. As venture funding in ocean-climate tech has exceeded $5 billion over the past decade, Propeller is well-positioned to be a leading voice in this emerging category.[5]
Influencing Ecosystem Standards
By insisting on scientific rigor and refusing oil company capital, Propeller is setting standards for how climate-tech investing should operate. The firm's partnership model with WHOI is being studied by other climate VCs as a template for embedding scientific expertise into investment decision-making. As the firm scales, it will likely influence how the broader venture ecosystem thinks about climate-tech due diligence and impact measurement.
Addressing Coastal Adaptation and Resilience
Beyond carbon removal, Propeller's portfolio spans industrial efficiency, shipping decarbonization, and coastal adaptation—recognizing that large portions of the global population live near coasts and will need to adapt to climate change.[1] This breadth positions the firm to capture value across multiple layers of the ocean-climate value chain, from emissions reduction to resilience infrastructure.
Quick Take & Future Outlook
Propeller represents a rare convergence of founder credibility, scientific rigor, and market timing. Brian Halligan's track record building HubSpot into a category leader gives the firm credibility with LPs and founders alike. The WHOI partnership provides a moat that's difficult for competitors to replicate. And the timing is propitious: federal policy support, rising corporate climate commitments, and growing recognition that net zero is impossible without ocean solutions are all working in Propeller's favor.
The firm's next chapter will likely involve scaling from its current $117 million deployed capital to significantly larger fund sizes, as the ocean-climate category matures and institutional capital recognizes the opportunity. Success will depend on whether Propeller's portfolio companies can achieve both climate impact and commercial returns—a challenge that will test whether ocean-climate innovation can move beyond niche applications to become a meaningful part of the global energy and food systems.
What makes Propeller compelling is not just its capital, but its conviction that the ocean has been systematically undervalued in climate solutions. If the firm can translate that conviction into a portfolio of breakout companies—the "narwhals" of ocean tech—it will have done more than generate returns; it will have catalyzed a reallocation of venture capital toward one of the planet's most critical frontiers.
