Shipping burns heavy fuel and is under growing regulatory pressure to cut emissions, and wind is the one energy source a ship can use at sea without refuelling. bound4blue, a Spanish company, makes the eSAIL: a rigid, wing-like tower with a fan inside that sucks air through its surface, keeping the airflow attached and generating far more thrust than a sail of the same size. The sails can be retrofitted to existing ships.
The European Innovation Council granted €2,396,802.30 towards a €3.42 million project to develop larger sails and test them on a Ro-Ro cargo ship. The EIC Fund then joined a €15.9 million Series A in 2023. In September 2026 bound4blue said its sails were deployed on 13 ships, with five more on order and more than 50 eSAILs installed or contracted, including a fleet order from Maersk Tankers.
Company file
- Legal entity
- Bound 4 Blue SL, Santa Cruz de Bezana, Cantabria, Spain (VAT ESB66341181)
- CEO
- José Miguel Bermúdez
- Product
- eSAIL suction sails, in several sizes
- Customers
- Odfjell, Maersk Tankers, Louis Dreyfus Armateurs, Marubeni, Marflet, among others
- Investors
- GTT Strategic Ventures (lead), EIC Fund, Shift4Good, Louis Dreyfus Company Ventures, CDTI Innvierte and others
- Classification
- Bureau Veritas design assessment; ABS review, per the company
- EIC project
- bound4blue, 1 Mar 2022 to 31 Aug 2024, closed
- EIC funding
- Blended finance
Where bound4blue Stands Today
On 1 September 2026 bound4blue announced that Odfjell had ordered four 22-metre eSAILs for its chemical tanker Bow Optima, for installation in 2027. It based the decision on the sister ship Bow Olympus, which it said achieved a "15-20% energy-saving effect in good, but not perfect, wind conditions". The release put bound4blue's fleet at 13 ships with eSAILs and five more on order, and more than 50 sails in total.
The company's orderbook page lists installations from a fishing boat in 2021 to a Ro-Ro ship and three larger vessels in 2024, and orders including five Maersk Tankers vessels with four of its largest sails each.
The Technology: A Sail That Breathes
A suction sail uses a fan to draw air in through slots on its surface. This stops the airflow from separating, so the sail produces lift at wind angles where a conventional wing would stall. bound4blue says its systems can reduce fuel use by up to 30%, depending on route and vessel; the Odfjell figure is the only measured result from a customer ship we found published.
"15-20% energy-saving effect in good, but not perfect, wind conditions."
Odfjell, on Bow Olympus, as quoted by bound4blue, September 2026What the EIC Project Promised, and What CORDIS Shows
The project ran from March 2022 to August 2024. According to the CORDIS report, three eSAILs were installed on a Ro-Ro vessel in February 2024 and tested at sea until July, with performance results "aligned with initial expectations". The report aims at fuel reductions of up to 30% but does not publish the trial's measured savings. The orderbook identifies the vessel as the 154 m Ro-Ro Ville de Bordeaux.
- Larger sails for big shipsDeliveredModel 2 and 3 sails, 22 to 26 m tall.
- Sea trials on a cargo shipDeliveredRo-Ro trials February to July 2024.
- Commercial adoptionDelivered13 ships and a Maersk Tankers fleet order.
- Published measured savingsPartialOne customer figure; trial data not published.
What Has Happened Since the Award
The Money
In September 2023 bound4blue announced €22.4 million in total: a €15.9 million Series A led by GTT Strategic Ventures, with the EIC Fund, Shift4Good, Louis Dreyfus Company Ventures and others, plus the €2.4 million EIC grant and a €4.1 million grant from the EU Innovation Fund. It planned to use the money to commercialise the eSAIL and expand production and staff. In December 2025 it closed a $44 million round led by OCTAVE Capital, affiliated with the shipowner IMC, and Katapult Ocean, with Motion Ventures, the Odfjell family office and the ReOcean Fund as new investors and Shift4Good, GTT Strategic Ventures, KAI Capital and Spain's CDTI (Innvierte) increasing their stakes. The release does not list the EIC Fund. The money is for production lines in Spain and China able to supply "hundreds of suction sails annually".
What cannot be checked
bound4blue's revenue, the EIC Fund's share of the Series A and whether it joined the 2025 round, and independently verified fuel savings are not public.
Why Europe Should Care
EU emissions trading now covers shipping, and the FuelEU Maritime rules push ships to cut greenhouse gas intensity. Wind-assisted propulsion is one of the few ways to cut fuel on existing ships, and bound4blue is a European supplier winning orders from major shipowners.
What the project promised
Advanced sails that reduce the environmental impact and operating costs of maritime transport.
What the record shows
A validated Ro-Ro trial, sails on 13 ships and fleet orders; measured savings mostly still unpublished.
The Verdict
A product that ships are buying
bound4blue used the EIC project to prove its sails at the size merchant ships need, and the orders that followed, from Odfjell and Maersk Tankers among others, are the best evidence that it worked. The EIC's grant and equity backed a company that is now scaling. What is still thin is independent, published data on how much fuel the sails actually save.
bound4blue has not been asked for comment for this article. It is based entirely on public records, company statements and EU project data, linked throughout.
