Market Watch: Diesel Outboards for Seaweed Harvesting in South Korea

As global demand for Korean food products continues to rise, South Korea’s seaweed industry is experiencing significant growth. Products such as kimbap, the popular seaweed rice roll that has gained widespread international attention, are driving increased demand for high-quality seaweed cultivation and harvesting. Alongside this growth, vessel operators are seeking more powerful and efficient propulsion solutions capable of handling larger boats, heavier payloads and longer operating hours.

Hugh Hudleston, Global Business Development Director at Cox Marine, shares his insights.

Growing global demand for kimbap is contributing to increased activity in South Korea’s seaweed harvesting industry 

When speaking with our South Korean distribution partner earlier this year, I learned that much of the country’s seaweed harvesting fleet has traditionally relied on smaller vessels and conventional propulsion systems. What was particularly striking, however, was the scale of investment now taking place as operators expand to meet growing demand. Some vessels now reach 28 tonnes and are operating further offshore to access productive harvesting areas. 

Why Seaweed Harvesting Vessels Are Upgrading Propulsion

These larger vessels place greater demands on marine propulsion systems. Operators require engines that can provide the torque and reliability needed to transport heavy loads of harvested seaweed while maintaining efficient performance throughout long working days. 

Some commercial operators are now using engines rated at up to 1,800hp, demonstrating the increasing power requirements of modern harvesting fleets. As vessels become larger and travel further offshore, propulsion systems must deliver consistent performance in demanding conditions while supporting productivity and operational efficiency. 

From what I am seeing across commercial marine markets, diesel outboard technology is increasingly meeting these requirements. 

How Commercial Diesel Outboards Deliver High-Torque Performance

For commercial operators, power is about more than top speed. Seaweed harvesting vessels need the ability to carry heavy equipment, crews and valuable harvests while maintaining efficient progress to and from port. 

Diesel engines naturally produce high levels of torque at lower engine speeds, making them particularly effective for moving heavily laden vessels. Rather than working harder as payloads increase, diesel power allows operators to maintain performance while reducing strain on the engine. 

Another advantage is that, by replacing traditional inboard engine installations with diesel outboards, operators can free up valuable internal space and maximise payload capacity. For seaweed harvesting vessels, this can support larger harvest volumes without increasing the overall size of the boat, helping to improve productivity and earning potential on every trip. 

This combination of torque, durability and efficiency makes diesel outboards particularly well suited to commercial marine applications where reliability is essential. 

Fuel Economy Benefits of Diesel Outboards for Commercial Operators

For vessel owners, fuel consumption remains one of the most significant operating expenses. According to commercial marine operators in South Korea, fuel economy is consistently identified as one of the biggest advantages of modern diesel outboard systems. While many manufacturers cite fuel-efficiency improvements of around 30% compared with equivalent petrol-powered engines, operators working in heavily loaded commercial applications report even greater savings. 

These improvements can have a direct impact on profitability, reducing daily fuel costs and helping operators maximise returns from every harvesting trip. 

Diesel vs Petrol Outboards: Understanding the 50% Fuel Saving Potential

Commercial operators in South Korea have reported fuel savings of up to 50% with Cox Marine diesel outboards compared with previous petrol equivalents. While we have previously cited 30% savings for many operating conditions, the benefit increases considerably when vessels are carrying substantial payloads, in applications such as seaweed harvesting. 

The reason lies in how each engine type performs under load. Petrol engines tend to consume significantly more fuel as demands increase, while diesel engines maintain more efficient fuel consumption. As a result, diesel-powered vessels effectively achieve the same working output while using considerably less fuel. 

For operators completing regular offshore harvesting trips, these savings can translate into substantial reductions in annual operating costs. 

Supporting Offshore Seaweed Harvesting Operations with Reliable Marine Engines

As harvesting activities move further offshore, operators need propulsion systems that provide not only efficiency but also reliability and range. Reduced fuel consumption allows vessels to travel greater distances between refuelling stops, helping crews maximise productive time on the water. 

From my perspective, the shift towards larger vessels, longer operating ranges and greater harvesting volumes is creating a strong case for commercial diesel outboards over more traditional petrol engines. Combined with their torque, fuel efficiency and reliability, diesel outboards are proving well suited to the evolving needs of South Korea’s commercial seaweed harvesting sector. 

 Looking to improve fuel efficiency and performance in your seaweed harvesting fleet?

Official Cox Marine distributor Soungjin Marine works with commercial vessel operators across South Korea to deliver diesel outboard solutions designed for demanding marine applications. Contact the team to discuss the right propulsion package for your vessel. 

About the Author

Hugh Hudleston is Global Business Development Director at Cox Marine, driving global growth and partnerships while championing advanced diesel outboard technology for government, commercial and high‑demand maritime operators worldwide. Passionate about supporting operators in demanding maritime environments, Hugh plays a key role in advancing Cox Marine’s presence across emerging and developing markets, where reliability, safety and mission assurance is critical.