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Navigating the Future: Energy Efficiency & Underwater Radiated Noise in Superyacht Design

Monaco, November 12th 2025

Setting the Scene: Why URN and Energy Efficiency Matter

The maritime industry is entering a transformative era, where energy efficiency and underwater radiated noise (URN) are no longer separate concerns, they are deeply interconnected challenges that demand integrated solutions. This was the central theme of the International Maritime Organization (IMO) Workshop, held in London on November 6–7, 2025, which convened over 300 participants, 150 attendees, 150 online, country delegates and industry leaders to explore the relationship between these two critical factors in the maritime industry.

This year’s workshop built on a series of IMO initiatives aimed at raising awareness of the environmental impacts of underwater noise. In July 2023, the IMO adopted new guidelines to mitigate vessel noise, which came into effect in October 2023. The first workshop in September 2023 focused on the link between energy efficiency and underwater noise, laying the groundwork for strategies that enhance both simultaneously. By October 2024, the Marine Environment Protection Committee (MEPC) had adopted a revised approach, including the URN Management Planning Reference Chart (effective December 2024) and a new Action Plan to reduce underwater noise from commercial shipping.

A key outcome of these initiatives was the commitment to host a second workshop in 2025, this time with a sharper focus on aligning energy efficiency and URN objectives across vessel types.

URN workshop IMO

IMO 2nd Underwater Radiated Noise Workshop

SEA Index Participation: Leading the Superyacht Sustainability Conversation

Under the aegis of ‘Monaco Capital of Advanced Yachting’ representatives from the SEA Index Superyacht Eco Association, Natalie Quévert and Rachel Ercole, were invited to the 2025 IMO workshop by key figures from the IMO and Bureau Veritas Marine Offshore. They participated in the dedicated poster session, a central feature of the event where technical solutions and environmental frameworks were presented and discussed.

With rising societal expectations and the increasing likelihood of future regulations affecting the superyacht sector, the demand for independent, science-based, measurable solutions has never been more urgent. The SEA Index’s mission: to champion innovative strategies that reduce the environmental impact of superyachts through enhanced energy efficiency and minimized underwater radiated noise, aligns closely with the IMO’s objectives and methodologies, including EEDI (Energy Efficiency Design Index) EEXI (Energy Efficiency for Existing Ships).

2025 Workshop Focus: Four Pillars of Progress

The workshop was structured around four key themes:

  • Day 1: Recent advancements in technical energy efficiency (EE) and URN reduction; integrated EE and URN management, including cost analysis and incentive structures.
  • Day 2: Progress toward unified design standards for EE and URN; application of predictive modeling to assess co-benefits and guide future objectives.

These sessions aimed to identify trends in EE and URN technologies, share insights from real-world management programs, develop integrated design standards, and foster cross-sector collaboration to achieve more efficient and less disruptive maritime operations.

Workshop Highlights: From Guidelines to Action

  1. Strategic Frameworks & Regulations

The IMO’s 2023 Greenhouse Gas Strategy provides global direction, though binding obligations remain limited. Regulatory frameworks such as MARPOL Annex VI and Chapter IV establish technical requirements for energy efficiency, with tools like EEDI, EEXI, and CII driving improvements across both new and existing fleets. URN management is now seen as essential, with revised guidelines addressing hull design, cavitation, and operational practices.

  1. Technological Innovations

Advances in propeller design, shaft power limitation, and energy-saving technologies (EST) are increasingly being integrated into efficiency calculations. Case studies such as the Enchanted Princess cruise ship illustrate the effectiveness of technologies like Silverstream ALS, which help achieve “QUIET” notation and significant URN reduction when optimized.

  1. Measurement & Incentivization

Ongoing URN monitoring and the use of innovative measurement methods both direct and indirect are vital for progress. However, high costs and complexity can be barriers, especially for smaller vessels. Evolving environmental incentive schemes, including the Environmental Shipping Index, are rewarding ships that exceed baseline performance, but must be carefully designed to ensure financial viability and widespread adoption.

  1. Holistic Planning & ROI

The workshop highlighted the economic advantages of integrating URN management with energy efficiency strategies. Owners are encouraged to see eco-innovation not just as a matter of compliance, but as a source of value, reputation, and operational excellence. Public recognition of these efforts amplifies their positive impact and inspires broader industry change.

International Maritime Organisation building outside view

Recurring Message from the Workshop

The central message of the IMO workshop was clear: the maritime sector must adopt integrated, actionable solutions that address both energy efficiency and underwater radiated noise reduction. Key points emphasized include:

  • Energy efficiency and underwater noise reduction are closely linked. Addressing both together delivers co-benefits for marine ecosystems and supports the shipping industry’s decarbonization objectives.
  • Affordable, reliable, and accessible measurement tools for URN, especially those usable directly by vessel operators are necessary for effective management and ongoing improvement.
    • Collaboration among industry, government, academia, and civil society is crucial to encourage innovation, sharing best practices, and accelerating the adoption of new standards and technologies.
  • Case studies and real-world examples show the tangible benefits of integrated management planning and incentive schemes.
  • Greater awareness, technical guidance, and incentivization are needed to encourage industry-wide adoption of noise reduction measures, moving from voluntary guidelines to more robust action plans.

Best Practices and Next Steps

  • Design for Silence: Integrate URN mitigation strategies from the earliest stages of ship design. By leveraging advanced hydrodynamics and structural calculations, new vessels can be optimized to minimize noise impact.
  • Measure What Matters: Implement cost-effective and scalable measurement solutions to collect and share valuable data, refine global models, and support evidence-based improvements.
  • Incentivize Excellence: Align financial rewards with strong environmental performance to encourage stakeholders to make sustainability a core business objective, turning responsible practices into smart business strategies.
  • Collaborate and Communicate: Actively engage with industry partners to accelerate the adoption of new practices and amplify the overall impact of sustainability initiatives.

Leadership in the Superyacht Sector: The SEA Index Perspective

The SEA Index is evolving beyond the CO2 rating system it pioneered in 2020. Working with Bureau Veritas Marine Offshore on Underwater Radiated Noise, it acts as a catalyst for meaningful change within the superyacht industry. By promoting collaboration among ports, marinas, shipyards, insurers, and regulatory authorities, the SEA Index establishes a common language for sustainability and encourages all stakeholders to work toward shared environmental goals. Its tools are designed to be adaptable, ensuring ongoing relevance as new technologies and industry standards develop.

Invitation to Join the New Era for Responsible Yachting

Achieving quieter and cleaner oceans requires a collective effort. By embracing innovation, transparency, and collaboration, the superyacht community is well-positioned to lead in environmental stewardship. SEA Index Superyacht Eco Association by Yacht Club de Monaco, invites all stakeholders to participate in shaping a responsible and dynamic future for yachting, ensuring the health of our oceans for generations to come.

To find out more, get in touch with our team, start the SEA Index certification process and your sustainability journey now!

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