255 years ago, a German doctor Johann Gottlob Leidenfrost discovered a phenomenon that when a liquid is exposed to a solid that is significantly above that liquid’s boiling point, forms an insulating vapor layer between itself and that solid; this is known as Leidenfrost effect.
The University of Melbourne’s Department of Mathematics and Statistics with Saudi Arabia’s King Abdulla University used the Leidenfrost effect on the ships, to help increasing ship’s speed.
The team leader Prof. Derek Chan believed that heating hull up to a temperature of over 100C (212F), that should cause a low-friction vapor layer to form between that hull and the water. He tested the theory by analyzing high-speed footage of polished balls being dropped through liquid – their drag was reportedly greatly reduced when they were heated to the point at which the Leidenfrost effect occurred.
Not only could this be used to reduce transportation costs and greenhouse emissions from shipping, he suggests, but it could also be used to speed the flow rate of liquid through pipes.
Chan does, however, admit that keeping the hull so hot could increase the rate of corrosion, and is further researching that possibility. There is also the question of whether the energy required to heat the hull (and keep it hot, as it’s exposed to cold ocean water) would be significantly less than the amount of energy that would be saved through the reduction of friction.