The Cantabria, Spain-based company, bound4blue, presented one of its six hybrid wind-propelled and heavy fuel oil-powered vessels at the world’s leading trade fair and conference event for the maritime industry: the SMM, held in Hamburg, Germany, this week. These ships equipped with eSails, are a successful testament to the industry’s journey towards CO2 neutrality, simultaneously reducing greenhouse gas emissions and transport costs.
The Amasus, currently moored in the port of Hamburg, looks like an ordinary ship at first glance. Yet the two masts at its stern, reminiscent of chimneys, clearly distinguish it from other vessels. They are high wind catchers that operate autonomously, aligning themselves according to the prevailing wind conditions. Sails in the traditional sense are nowhere to be found. The electronically steered system works by dragging air across an aerodynamic surface, generating exceptional propulsive efficiency. The simple, low weight and easy to install units significantly cut main engine loads, fuel use and emissions.
Not suitable for large box ships
Operated across the North Sea between the Netherlands and Norway, for example, vessels like the Amasus can reach a speed of between 10 and 12 knots, or around 20 km/h in metric terms. This is roughly equivalent to the speed of a ferry boat crossing the English Channel between Le Havre and Portsmouth. eSails best fit tankers, bulkers, ro-ros, cruises, ferries, gas carriers, and general cargo vessels, regardless of their size or age. They are not suitable for container ships as there is not enough space for the necessary reinforcements of the ship’s structure in the area where the sail posts are fixed.
Fast cost amortization
If a shipping company decides to modify one of its medium-sized vessels, it can expect a cost of around 500,000 euros per eSail, twice as much for two installations similar to the Amasus type. eSails are pre-assembled and installed on a given vessel in a dry dock. Technically, this is no rocket science, says José Miguel Bermudez, CEO of bound4blue. As experience shows, the task can be accomplished within two days, he says. The costs amortize themselves in a relatively short time. Bermudez speaks of three to five years, depending on the shipping area. In the windy North Sea, the financial recovery time for ship owners is significantly shorter compared to sailing areas with low wind conditions.
Reducing CO2 emissions
By operating eSails, up to 30% greenhouse gas emissions can be avoided; however, more realistic are savings between 10% and 20%, the manager admits.
“You should take a look at the order book from bound4blue. It’s full to bursting,” says Rasmus Stute, Area Manager Germany, DNV. This is confirmed by Mr. Bermudez, who speaks of up to 50 eSails that will be manufactured and introduced to the market during the course of 2025. “In the next two months, we will announce three additional contracts.”
Last Wednesday, the eSail received a full Type Approval Design Certificate (TADC) from Norway’s DNV. The certificate, handed over to the management on board the Amasus, validates complete compliance with the technical standards specified in the classifier’s Wind Assisted Propulsion Systems (WAPS), demonstrating that the team’s breakthrough suction sail technology is in line with the industry’s most advanced rule set.
“Receiving the TADC from DNV provides third-party validation of excellence, quality stamping our system and helping fast-track customer due diligence procedures. We believe this will work to accelerate the adoption process and facilitate further orders,” commentedDavid Ferrer, Co-Founder and CTO of bound4blue.
Building confidence in the wind technology
On the DNV certification occasion, Hasso Hoffmeister, Senior Principal Engineer at DNV Maritime, notes: “Wind is an inexhaustible, free, zero carbon energy source, which is receiving increasing attention within the maritime industry. To harness its potential, owners require trusted systems with validated technical and design compliance, to ensure the highest quality standards. DNV, is committed to helping our customers innovate and build confidence in these new technologies on a foundation of trust.” The manager went on to say: “Our cooperation with the team at bound4blue has been excellent, and we’re very pleased to award this certification. We look forward to seeing the growth of wind as a green energy source for vessels worldwide, as we work together to make the maritime industry even more sustainable for the generations to come.”
