FOR years, wind propulsion has sat awkwardly in shipping’s decarbonisation debate: too established to dismiss, yet too niche to scale up.

Advocates say it’s the perennially overlooked answer to cleaner shipping, while critics argue it’s romantic, but no more than a rounding error when it comes to net zero. Might that be changing?

The biggest announcement at SMM Hamburg this week was not about methanol or ammonia. Instead, it was Maersk’s decision to trial a 35 m rotor sail on an 8,700 teu containership from next year.

It will be the first deployment of wind-assisted propulsion on a boxship, testing one of shipping’s oldest technologies in one of its most demanding segments.

Mechanical sails have taken flight in recent years; more than 100 of them have been installed on bulkers, tankers and PCTCs, and another 80 are on order.

But not, until now, on containerships. Cargo stacks leave little spare deck space and create complicated aerodynamic challenges. If wind propulsion can demonstrate meaningful fuel savings in liner operations, one of the industry’s most important barriers to broader adoption could start to fall.

Predicting fuel savings confidently enough to spend millions on a complex installation has always been the hard part with wind.

Big data is helping to overcome this. Early adopters such as Norway’s Odfjell have spent years collecting operational data on fuel savings, reliability and crew acceptance. Its decision this week to fit a second vessel with suction sails suggests confidence is growing beyond pilot projects.

Yet wider uptake still depends on the economics. Fuel savings vary by route, weather and vessel design. Installation costs remain significant, and too often owners must pay them while charterers reap the fuel benefit.

That is why data has become the industry’s new battleground. Standardised performance measurement, transparent reporting and route optimisation may prove as important as the hardware itself. Shipowners need evidence, not promises.

Regulation is strengthening the business case, alongside high bunker prices. FuelEU Maritime, regional carbon pricing and prospective IMO measures are increasing the value of every tonne of fuel saved.

Wind propulsion can’t clean up shipping on its own, but it is making progress, while deeper decarbonisation languishes in the doldrums.

Let’s see if this latest trial can deliver for Big Blue.

Declan Bush
Senior reporter, Lloyd’s List 

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