When the Kwai was launched in Bremen in 1950, it was named "Bayern" and was used as a motor vessel. After a long career, it was acquired in 2005 by Captain Brad Ives, who rigged it as a ketch and, from 2006, began operating it as the "Kwai" on a regular cargo service from Hawaii to the Cook Islands and Kiribati (Hudson River Maritime Museum, 2022). Since the remote islands with few inhabitants are not lucrative for shipping companies and fuel prices are high, transport by sail filled a gap in the market. The Kwai has a cargo hold of 300 cubic meters, can carry 220 tons, and is about 43 meters long. It sails with a crew of 8 to 11 sailors and also takes passengers.
The Kwai, later renamed Tarmelu.
Unlike most ships in the European cargo sailing movement, the Kwai did not transport selected organic products, but rather diesel barrels for generators on small islands, machine spare parts, bicycles, agricultural raw materials such as copra, and everyday goods, among other things.
In between, the Kwai was used to fish plastic waste out of the ocean. In 2021, it was sold to the Marshall Islands. There it was renamed “Tarmelu,” the name of the first traditional female sailor in the Marshall Islands.
Small states threatened with extinction
Anyone concerned with the ocean and climate change will soon come across the politics of the Pacific island states. With sea levels rising due to global warming, their very existence is under acute threat. The low-lying islands will sink, swallowed by the ocean, and millions of people will lose their homes. They are therefore very active in climate diplomacy. Many ships in the European cargo sailing movement are associated with this policy by sailing under the flag of Vanuatu, a state whose activities have resulted in important climate rulings by the International Tribunal for the Law of the Sea and the International Court of Justice – the highest court of the UN.
The Marshall Islands also play an important role. Their then foreign minister, Tony der Brum, was not only committed to the fight against nuclear weapons, for which he received the Alternative Nobel Prize, but also took a clear stance on climate change: “We think that the more reasonable thing to do is to seek to end this madness, this climate madness, where people think that smaller, vulnerable countries are expendable and therefore they can continue to do business as usual.” (Perry, 2017) At the 2015 UN Climate Change Conference in Paris, he succeeded in forming a “High Ambition Coalition” between developing and industrialized countries. This contributed significantly to the climate conference ending successfully with the Paris Climate Agreement. For this, he was awarded the German Environmental Prize after his death.
Ambivalent role
In December 2020, the country set itself the goal of reducing its greenhouse gas emissions from domestic shipping by 40 percent by 2030 compared to 2010. The aim is to reach zero emissions by 2050. “The Republic of the Marshall Islands is a global leader in promoting measures against climate change and the only country to explicitly include domestic maritime transport in its nationally determined contributions (NDCs).” (Fedlmeier et al. 2022)
The catch: this only applies to domestic maritime transport, because on paper, the Marshall Islands is home to the third-largest merchant fleet in the world. Shipowners do not usually register their ships under the flag of their country of residence. By flagging out, they circumvent the collective agreements, labor and environmental protection laws of their home countries and pay lower taxes. They pay only a small fee to register in flags of convenience countries. The Marshall Islands, a small country, is the third-largest provider of flags of convenience. With a population of 43,000, there are around 6,000 registered ships, or one ship for every seven people.
The Marshall Islands has outsourced the registration business to the private company International Registries Inc. based in the USA. This is quite common practice. However, it changes the character of the UN shipping organization IMO: The employees of private companies who represent the member states at meetings can determine the position of their government, reports the anti-corruption organization Transparency International (Transparency International, 2018). In 2015, Tony de Brum came to the IMO with the message that if it did not set ambitious climate targets, this would have catastrophic consequences for low-lying islands. As foreign minister, he discovered that the Marshall Islands' seats were already taken. “We had some difficulty convincing the people who were sitting in our seats, literally, that we were the representatives of the Marshall Islands.”
“De Brum’s intervention revealed a struggle between the world’s second largest shipping registry and its flag state over who the IMO really serves – sovereign states or the shipping industry?" concludes the British organization Climate Change News. “It also highlights deep cultural issues within the IMO – a UN body where delegations are invariably stacked with industry representatives and national interests are oddly peripheral." (Gibbs, 2017)
The Kwai now sails as Tarmelu
With the purchase of the Kwai – aka Tarmelu – the Marshall Islands became the first country in the world to own a cargo sailing ship. And the Kwai became part of the expansion-oriented Low Carbon Sea Transport Project. This is based in the Republic of the Marshall Islands. It is funded by the International Climate Initiative (IKI) of the German Federal Ministry for the Environment with funds that Germany has pledged under the Paris Climate Agreement.
On the German side, the project is led by the German Society for International Cooperation (GIZ) and the University of Emden Leer. In its study, the latter states: "About 150 years ago, the Marshallese sea transport and trading network was based on large canoes with capacities for several tons of freight and up to 50 passengers. These canoes were perfectly adapted to the local weather conditions and operated at almost twice the speed of today's vessels when using favorable wind patterns. They were built from natural and locally available resources." (Vahs et al., 2019) In other words, the canoes of that time were not only climate-neutral, but in some respects even superior to today's fossil-fuel-powered ships.
The authors of the study also conclude that for the future: "As a technical measure to directly and significantly reduce the required thrust, wind propulsion technologies can be seen as the most important technically feasible option on the demanding road to emission-free maritime transport. There is currently no other option available that meets the requirements for zero-emission maritime transport. The only conceivable alternative solutions that could be ready in the near future are electric hybrid drives (today energy storage is the main cost driver), the use of biofuels (currently still too expensive in production costs) and fuel cell technology (requires hydrogen storage or similar variants). However, these alternative solutions do not contradict the use of wind propulsion but are a very good complement if they develop into efficient alternatives from an economic point of view." (Vahs et al., 2019)
The construction of the Juren Ae
Domestic maritime transport plays a central role for the Marshall Islands. The country consists of two chains of flat atolls stretching northwest from the capital, Maduro, located on a southern island. Imports and exports are handled via Maduro. From there, goods must be transported to the other islands. Copra, dried coconut meat, is then returned in sacks. Copra production is the most important agricultural sector on the islands.
Since the Ratak and Rallik island chains lie to the northwest of the national port of Majuro and winds predominantly come from the northeast, ships can usually sail on a beam reach course.
This means that flexible general cargo ships are in demand. Since the trade winds blow from the east-northeast all year round, these ships mainly encounter side winds on the main routes. This makes the Marshall Islands a suitable area for sailing freighters, as they can often sail on a favorable beam reach. Since there are generally no ports on the atolls, freight and passenger traffic must be handled by boats anchored in the shallow waters of the lagoons.
The purchase of the Tarmelu 2021 made it possible to immediately gain experience in transport by sail, with a ship that had already proven itself under such conditions. At the same time, the prototype for the future fleet of island supply ships was developed in Germany at the University of Emden/Leer. Construction of the Juren Ae began in South Korea in 2023, and it was delivered to the state-owned Marshall Islands Shipping Corporation in 2024. The name Juren Ae comes from the language of the Marshall Islands and refers to the paddle of the traditional outrigger canoe, which is used as a rudder to steer in the desired direction.
Plan of Juren Ae.
The Juren Ae is 48 meters long (length above deck 43.4 meters) and 8.70 meters wide and can transport up to 300 tons of general cargo between the atolls in its 600 cubic meter cargo hold. Under sail, the three-masted ship reaches around 12 knots, and under engine power a maximum of 9.7 knots. The maximum sail area is 555 square meters.
It is equipped with an Indosail rig, which can be operated manually in an emergency, but in everyday use can be operated from the bridge or deck at the touch of a button. This requires a reliable power supply. The power comes firstly from a photovoltaic system, secondly from diesel generators, and thirdly, when sailing, the propeller can also drive a generator.
This picture of the construction clearly shows the relatively flat underwater hull.
With a maximum draft of 3.20 meters (when loaded), the Juren Ae sits low in the water for a sailing ship of this size. By comparison, the Tres Hombres, which is around 20 meters shorter, has practically the same draft. The flat hull is necessary for navigating the lagoons. To prevent the Juren Ae from drifting too much on close-hauled and half-wind courses, it was equipped with newly developed bilge keels in the stern, known as Wagner keels (Wagner et al. 2025). The hull shape proved its worth during the first maneuvers at sea: "The sailing system was tested during an additional trial run. During this time, the ship demonstrated excellent maneuverability and course stability. The aerodynamic and hydrodynamic forces were well balanced, and only very small rudder angles were required to compensate for yaw moments. The ship demonstrated particularly good turning behavior under sail" (Strasser et al., 2025).
The Juren Ae was built as a prototype for a transport fleet to sail the open seas and provide supplies to the widely scattered atolls. Small sailing catamarans (right) will enable climate-neutral transport in the lagoons within the atolls in the future.
The Juren Ae is a prototype. Emden Leer University of Applied Sciences is investigating how it performs in practice with a view to building further ships. Other island states have already expressed interest in this type of ship.
In addition to cabins for the eight crew members and twelve passengers, there is space for six trainees. This is because the ship is also explicitly designed as a training vessel. A maritime training programme has been launched to train specialist personnel for the future fleet of sailing freighters, with a specific focus on training women.
This video shows how a sailing cargo ship can encourage.
Indigenous knowledge is integrated
Ships such as the Tarmelu and the Juren Ae are designed for transport on the open sea. However, a large part of water transport takes place within the lagoons of the atolls. Forty per cent of greenhouse gas emissions from inland shipping come from small boats in the lagoons (PRIF, 2018).
Greenhouse gas emissions from domestic shipping in the Marshall Islands. MISC is the state-owned shipping company that operates the sailing freighters Tarmelu and Juren Ae, among others. The high proportion of boat traffic within the lagoons is striking.
In order to make transport within the lagoons climate-friendly, indigenous knowledge from the Polynesian tradition of multihull boats is being drawn upon.
The catamarans used for transporting goods and passengers within the lagoons utilise the traditional sails of the proas, the outrigger boats of the Marshall Islands.
Simple catamarans are being developed for transporting cargo and people under sail. Boat builders are trained in workshops and plans are distributed for catamarans that can carry up to a tonne – considerably more than the small outrigger canoes (proas) that are often still used for fishing. This ‘WAM Catamaran’ has a spacious cargo hold for copra, for example, is 6 metres long, but could also be built up to 10 metres long. The projects draw on indigenous boat-building traditions, which did not use metal parts, but integrate modern boat-building plywood and epoxy resin. Here is a film about it: https://www.youtube.com/watch?v=xsWx47FloWo.
Stopping the disaster?
The good news from the Pacific shows that as soon as a technology such as cargo transport by sail is subsidised by the state for climate reasons and public funds are made available, great progress is possible. Innovation and tradition merge in the process. In the case of the small islands in the Pacific, fossil fuels are comparatively expensive, making wind an attractive free fuel. Maritime transport there is less about trade and more about supplying the population, a function that trucks perform in continental countries. The atolls consist of so little land that transport by water is the logical choice.
The contradictory message is that, on the one hand, the Marshall Islands are playing a pioneering role in wind-powered transport – and thus in an important part of the fight against the climate crisis – and are training future sailors, for example, with the Jela Meto Centre Maritime Training Programme. On the other hand, the same state has a market share of around 11 per cent in the global business of flags of convenience, which allow shipowners to drive down wages and reduce taxes. This is one of the reasons for the excessively cheap sea transport that, as the backbone of globalisation, enables industrial exploitation in low-wage countries on the one hand, and extended supply chains and the flooding of consumer markets in rich countries with wasteful and disposable items on the other.
The bad news is that even with consistent climate policies – exemplified by sea transport under sail – the small Pacific states, with a population of people who live very modestly and have so far caused very little greenhouse gas emissions, cannot stop their sinking. Admittedly, their political will to become climate neutral by 2050, not just on paper but in reality, is more palpable than in the rich countries, whose measures are completely inadequate. And it is these countries that are driving sea level rise.
Climate solidarity would mean pushing ahead with the necessary transformation in the rich countries as well. This would mean changing our economy and lifestyle to comply with the international laws that our governments have signed. The emphasis on these laws by courts – for example, that marine pollution caused by greenhouse gas emissions is prohibited – had to be fought for first by the small island states. But so far, we have simply continued to ignore this.
References
Fedlmeier, Christian; Held, Raffael (2022): Transitioning to Low Carbon Sea Transport. Project Concept for Low-Emission Sea Transport in the Marshall Islands, the Pacific Region, and Internationally. Berlin, Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Gibbs, Margot (2017): The tax-free shipping company that took control of a country’s UN mission, in Climate Home News, 6.7.2017. https://www.climatechangenews.com/2017/07/06/tax-free-shipping-company-took-control-countrys-un-mission/
Hudson River Maritime Museum (2022): Sail Freighter Friday - SV Kwai (2006-Present), https://www.hrmm.org/history-blog/sail-freighter-friday-sv-kwai-2006-present
Pacific Region Infrastructure Facility PRIF (2018): Establishing Baseline Data to Support Sustainable Maritime Transport Services. Focused on the Republic of the Marshall Islands (RMI). FINAL REPORT. Sydney, New South Wales, Australia. https://www.theprif.org/sites/theprif.org/files/documents/prif_rmi_shipping_baseline_data_report_2018.pdf
Perry, Nick (2017): Tony de Brum, global voice for fighting climate change, dies. AP, August 23, 2017, https://apnews.com/general-news-684ec98cff254c47972501a2ac1cd49a
Republic Of The Marshall Islands (2024): Vessel Registration And Instrument Recording, https://www.register-iri.com/wp-content/uploads/MI-100.pdf
Strasser, Sascha; Wagner, Siegfried, Vahs, Michael (2025): Development, Construction and Operation of the Primarily Wind-Powered Cargo-ship JUREN-AE for the Republic of Marshall Islands, HIPER Konferenz 2025
Transparency International (2018), Governance at the International Maritime Organisation: The case for reform. https://www.transparency.org/en/publications/governance-international-maritime-organisation
Vahs, Michael; Wagner, Siegfried; Peetz, Thomas; Strasser, Sascha; Richter-Alten, Henrik; Arriens, Christian (2019): Technical and Operational Options Catalog, Proposal for Technical and Operational Options to reduce Fuel Consumption and Emissions from Inter-Atoll-Transport and Inside-Lagoon-Transport, Emden/Leer: University of Applied Sciences. https://mcstrmi.org/images/Projects/TLCSeaT_HEL_TechnicalAndOperationalOptionsCatalog.pdf
Wagner, Siegfried; Strasser, Sascha; Vahs, Michael (2025): Keel Concept for Modern Wind-Assisted Commercial Ships based on the Vortex-Lift Principle. Journal of Sailing Technology 2025, volume 10, issue 1, pp. 279 – 313. The Society of Naval Architects and Marine Engineers. https://onepetro.org/JST/article/10/01/279/789579/Keel-Concept-for-Modern-Wind-Assisted-Commercial