The New Age of Sailing

99,800 cargo ships. Almost all of them burn the cheapest, dirtiest fuel available, releasing sulfur contaminants and 837 million tons of carbon dioxide a year. We need their emissions not just reduced, but slashed, within a few years. Welcome to a new age of sailing.

Bulk cargo carrier Pyxis Ocean. Built in 2017, fitted with wingsails in 2023. Photo: Business Wire.

Pyxis Ocean is the first convert. It was a standard bulk cargo carrier until it was selected to test sails developed by BAR Technologies. The sails are expected to cut the ship’s fuel use by 30%. Such a dramatic improvement in efficiency just from two sails gives hope both for cutting emissions and promoting alternative fuels: e-methanol might enter the shipping market at 8-times the price of conventional fuel, so the fact that bolting sails onto a ship slashes the fuel costs will yield hefty savings and make switching to green fuels more palatable while the prices come down. More sails, more savings. And come down the prices will—as capacity and competition arrive in green fuel production, we may see a similar plunge in price as solar panels saw early in their development. Solar started above 115 US$ per Watt in 1975 and fell below 32 US$ in just 5 years (now that price is about 27 cents US).

While most cargo ships are candidates for refitting, not all can use these sails. Container ships lack space on deck for a large, rotating, jointed wing that folds down to pass beneath bridges. Some shipping routes lack consistent wind. But for the many ships that can accept them, a few wingsails could prevent the emission of 20 tons of carbon dioxide, per ship, per day.

They call them “wingsails” for good reason: this emerging generation of sails has more in common with an airplane’s wing than with the squares and triangles of canvas that caught wind for cargo ships before diesel took over.

Pamir, the “last commercial sailing ship”, under sail. Built in 1905, Pamir operated under various companies until her sinking in 1957. Like Pyxis Ocean, Pamir was also a bulk cargo carrier. Photo: the Vintage News.

The wing-like shape of wingsails gives them a crucial advantage over the sails of old. When the wind blows any direction except directly behind the ship, a wingsail has lower drag and produces more lift than a sail. A variety of wingsail designs are emerging, from rigid aerofoils with moving parts, to soft fabric-covered wireframes, to inflatable variants.

A small boat with an inflated wing sail. This sail can be deflated and the mast retracted when not in use. Photo: Sail Universe.

Such new sails will be the most obvious, but not the only innovation moving from small boats to large commercial ships. For decades, sailing was a niche activity: the activity of racers and hobbyists. The first wingsails emerged on tiny boats, like the Optimist Dinghy, which proved easy to handle and fast. So fast that races dedicated to the Optimist quickly went international and have continued ever since. Other technologies from similarly small boats are being examined for fitting to the big commercial vessels, including high-efficiency propellers whose blades loop back on themselves.

A toroidal boat propeller, 3D printed by an enthusiast. Photo: PROPDESIGNER

New sails, better propellers, and new power sources are just the start as large shipbuilders and shipping companies begin looking beyond their own past for inspiration to address their carbon footprint.