Houlder: Slow steaming is not a one-size-fits-all solution

While it may be advantageous for some vessels, its suitability and efficiency depend heavily on the specific characteristics of each ship. With numerous options available to meet stringent environmental regulations, Shin stresses the need for stakeholders to carefully evaluate alternatives, ensuring operational flexibility is maintained rather than automatically adopting slow steaming as the default approach.

SAFETY4SEA: What is your company’s philosophy for the maritime industry and what are the top priorities on your agenda for the next five years? 

Iebum Shin: At Houlder, our philosophy for the maritime industry is clear: to decarbonise ships and shipping through independent advice, design, and engineering. We are committed to delivering solutions that combine good sense, smart design, and practical know-how to address the most pressing challenges in the maritime and offshore industries. Over the next five years, our priorities are centred on five key areas: First, decarbonising ships and shipping remains at the heart of what we do. By delivering innovative and pragmatic solutions, we aim to reduce emissions and enable a more sustainable maritime future. Second, we will remain dedicated to tackling installation challenges for offshore renewable energy. As offshore renewables grow, we support this expansion by overcoming the technical and logistical barriers to installation, ensuring projects are delivered efficiently and effectively. Third, we’re focussed on driving better investment and operational decisions for our clients. Through the use of data, simulation, and analysis, we help stakeholders make informed choices that enhance efficiency, profitability, and long-term sustainability. Fourth, we aim to assist the industry in navigating complexity. Whether it’s addressing regulatory changes, managing the impact of rapid technological advancements, or responding to climate imperatives, we provide clarity and direction to guide our clients through these challenges. Finally, we will continue to maintain independence and objectivity. As a trusted and impartial advisor, we deliver solutions that are not only right for our clients but also benefit the maritime industry as a whole.

S4S: What are the main drivers behind the recent trend of slow steaming among shipowners?

I.Sh.: The trend of slow steaming among shipowners is primarily driven by the desire to reduce fuel consumption, lower operating costs, and comply with tightening environmental regulations aimed at reducing greenhouse gas emissions. By operating at reduced speeds, ships can significantly decrease their fuel usage, which in turn cuts both carbon emissions and costs. This has made slow steaming an attractive option for many in the industry, particularly in the face of evolving regulatory frameworks like the IMO’s Carbon Intensity Indicator (CII) and the broader push toward decarbonisation. However, it is important to recognise that slow steaming is not a one-size-fits-all solution. While it can be beneficial for certain vessels, its effectiveness and practicality are highly ship-specific.Any speed reduction could result in a significant departure from a vessel’s original design parameters, so the benefit of corrective measures should be considered too. For example, a simple hull retrofit or propeller optimisation to align with the vessel’s new operating conditions could be the difference between slow steaming delivering minimal or real benefits. Moreover, there are often “low-hanging fruits” that shipowners can pursue before resorting to slow steaming, such as retrofitting energy-saving technologies, optimising hull performance, improving voyage planning, or enhancing onboard operational efficiencies. By exploring these alternatives, shipowners can achieve meaningful gains without compromising operational flexibility or resorting to slow steaming as a default strategy.

S4S: What specific design parameters do shipowners need to pay attention to before implementing slow steaming?

I.Sh.: When implementing slow steaming, shipowners must carefully assess how a vessel’s design parameters will perform at reduced speeds to maintain efficiency and operational integrity. A key consideration is the vessel’s speed profile, which involves understanding the difference between its current operational speed and its original design speed. This analysis is essential to gauge how slow steaming might impact overall performance. At lower speeds, auxiliary systems may operate at reduced loads, potentially leading to inefficiencies or increased power consumption. Therefore, it is important to evaluate the auxiliary power arrangements to ensure they remain effective under these conditions. Similarly, propeller efficiency can decline at off-design speeds since propellers are typically optimised for a vessel’s design speed. Assessing the propeller’s performance at reduced speeds helps to identify any loss of efficiency and potential areas for improvement. Another crucial factor is the hull shape, which is designed to perform optimally within a specific speed range. Operating outside of this range can affect hydrodynamic performance, so shipowners must analyse how the hull behaves at lower speeds and determine whether modifications are necessary to sustain efficiency. By thoroughly addressing these interconnected factors – speed profile, auxiliary systems, propeller efficiency, and hull performance – shipowners can make informed decisions on slow steaming, balancing economic benefits with environmental performance while maintaining the vessel’s overall effectiveness.

S4S: How does slow steaming align or conflict with the IMO’s greenhouse gas (GHG) reduction targets?

I.Sh.: The International Maritime Organization’s (IMO) greenhouse gas (GHG) reduction targets are rooted in the principles of the 2015 Paris Agreement, which aims to address climate change and its wide-ranging negative impacts. Slow steaming, when implemented correctly, can align with these targets by reducing fuel consumption and, consequently, GHG emissions. However, the benefits of slow steaming depend heavily on its application. If slow steaming leads to significant schedule disruptions or requires additional vessels to meet demand, the net effect could increase overall emissions, which would conflict with the IMO’s reduction goals. Achieving alignment requires a balanced approach that considers operational efficiency and avoids unintended consequences, such as the need for supplementary shipping capacity.

S4S: What roles does technology play in helping shipowners find the optimal balance for slow steaming?

I.Sh.: We believe that technology plays a pivotal role in helping shipowners achieve the optimal balance for slow steaming. The right technology solutions offer efficiency improvements that enable compliance with emission regulations, positioning slow steaming as a valuable option to explore for additional savings when feasible. Advanced technology can further unlock the full potential of slow steaming, whether it is adopted as a long-term strategy to meet regulatory requirements or utilised as an operational tool to achieve economic gains. By providing critical data and insights, technology empowers shipowners to make informed decisions on vessel speed, fuel consumption, and overall performance, ensuring optimal outcomes for both environmental and commercial objectives.

S4S: Slow steaming is often seen as a low-cost option, but Houlder highlights hidden CAPEX and OPEX costs. How can shipowners mitigate these costs effectively?

I.Sh.: While slow steaming is often regarded as a cost-effective method for improving vessel efficiency, shipowners must be mindful of its hidden capital expenditure (CAPEX) and operational expenditure (OPEX) implications. To mitigate these costs effectively, a proactive approach should be deployed, focused on machinery assessment, modifications, and maintenance planning. First, shipowners should assess their current machinery arrangements and consult with manufacturers to determine whether modifications or operational changes are needed to accommodate slow steaming. Engines and associated systems are typically designed to operate at higher loads, and running them at reduced speeds can result in inefficiencies or long-term damage. By proactively addressing these issues, shipowners can ensure that machinery operates efficiently under lower loads, avoiding unplanned expenses and potential system failures. Second, shipowners need to evaluate the impact of slow steaming on maintenance frequency and costs. Operating engines at lower loads can lead to increased wear, fouling, and other performance-related issues, which may necessitate more frequent inspections and servicing. Understanding these changes allows shipowners to adjust their maintenance strategies to manage OPEX effectively, while ensuring operational reliability.

S4S: What alternatives to slow steaming can offer shipowners competitive advantages without the drawbacks of speed reduction?

I.Sh.: While slow steaming has been widely adopted to reduce fuel consumption and emissions, it presents notable drawbacks, including reduced cargo capacity and the inability to meet demanding schedules when higher speeds are required. Shipowners seeking competitive advantages without sacrificing speed can consider several alternative strategies. First, enhancing schedule reliability and ensuring faster delivery can significantly improve operational efficiency. By prioritising predictable and dependable transit times, shipowners can offer greater value to customers who increasingly demand reliability. Faster and more consistent delivery can serve as a powerful differentiator in competitive markets. Second, the adoption of new technologies and ship modifications provides an effective way to improve vessel performance. Innovations such as hull optimisation, upgraded propulsion systems, and energy-efficient retrofits allow ships to minimise fuel consumption and emissions while maintaining speed and operational flexibility. These advancements support environmental goals without compromising on performance. Finally, a focus on operational knowledge and long-term solutions enables shipowners to optimise their fleets beyond short-term fixes like speed reduction. By proactively analysing their operations, shipowners can identify efficiencies, streamline performance, and implement strategies that future-proof their businesses against evolving market and environmental demands.

S4S: Do you have any projects/ plans that you would like to share with industry stakeholders?

I.Sh.: Houlder is actively engaged in several innovative projects and initiatives focussed on delivering practical, sustainable, and impactful solutions for the maritime sector. By implementing simple yet effective engineering solutions, we have demonstrated measurable fuel savings and efficiency gains. A key example is our transom modification (duck tail) design for Siem Car Carriers, which showcased how simple engineering enhancements can deliver significant operational and environmental benefits. Another area of development is the Houlder Optimisation and Modelling Environment (HOME). This physics-based operational simulation platform allows us to test new concepts, validate emerging technologies, optimise vessel designs, and assess operational strategies, such as slow steaming. By leveraging HOME, we are enabling our clients to achieve enhanced efficiency and sustainable outcomes for both current and future projects. We also participated in the SWOPP project – a benchmarking workshop on wind-assisted propulsion systems organised by the Research Institute of Sweden (RISE, formerly SSPA). This global event brought together research institutes, shipyards, and classification societies to advance performance prediction methodologies for wind-assisted technologies, reflecting our focus on innovation and collaboration.

S4S: If you could change one thing across the industry from your perspective, what would it be and why? 

I.Sh.: A key area we would focus on improving across the industry is port infrastructure. The efficiency of port operations directly impacts the overall effectiveness of the maritime supply chain. Streamlining the flow of vessels, better communication of slot timings, and more synchronised scheduling would make a significant difference in reducing delays and increasing efficiency. Looking at other engineering sectors, such as aviation, we see how beneficial it can be when industries prioritise knowledge sharing. Aviation has made great strides in this area, and if the maritime sector could adopt a similar approach to sharing best practices and collaborating on new technologies, it would likely accelerate advancements in sustainability and efficiency. Another crucial consideration is emissions. While much focus is often placed on reducing emissions from ships, we need to consider the entire ecosystem – from fleets to supply chains – to drive a holistic reduction in environmental impact. Working towards more integrated solutions across the entire logistics chain is essential for the industry to meet its sustainability goals.

S4S: What is your key message to industry stakeholders to foster a more sustainable future for shipping?

I.Sh.: We’d encourage the industry to harness the power of experience and advanced analytics to drive timely, reliable, and relevant decisions that shape a more sustainable future for shipping. By leveraging data-driven insights and our extensive industry experience, we can support the transition to greener, more efficient practices that not only reduce environmental impact but also improve operational performance and economic viability. Together, we can accelerate the adoption of sustainable solutions and ensure a resilient, low-carbon future for the shipping industry.

The views presented are only those of the authors and do not necessarily reflect those of SAFETY4SEA and are for information sharing and discussion purposes only.