Best answer: Some companies have designs for such wind/sail cargo or tanker ships...time will tell if they become more popular and useful. Modern Rotor Sail designs using the Magnus effect which date back to the 1920's may be an easier and better way to achieve cost reductions in fuel consumption.
"Wind power firm Enercon launched a new rotor ship in 2008, while in 2014 Norsepower added its first rotor sail to a cargo ship owned by sustainable shipping firm Bore. Promising lightweight and relatively cheap materials and designs, combined with higher oil prices and the need to reduce emissions, mean rotor sails could now take off.
The 240 metre-long Maersk tanker will be retrofitted with two modernised versions of the Flettner rotor that are 30 metres tall and five metres in diameter. In favourable wind conditions, each sail can produce the equivalent of 3MW of power using only 50kW of electricity. Norsepower expect to reduce average fuel consumption on typical global shipping routes by 7% to 10%, equivalent to about 1,000 tonnes of fuel a year."
http://theconversation.com/spinning-sail...
"Currently, the shipping industry alone produces 2.2 percent of the world's carbon emissions. The International Maritime Organization estimates that could increase by 250 percent by 2050 if nothing is done to stop it. By switching to the Rotor Sail hybrid method, the savings for the industry would total $7 billion a year, and it would reduce the emissions by the equivalent of 12 coal power plants."
https://www.popularmechanics.com/technol...
https://www.nytimes.com/2012/08/28/scien...