![]() Science & Technology || Search || Back Numbers SMOOTH SAILING:
![]() Water beads right up on the highly repellent coating. (Photo: Mitsui Engineering and Shipbuidling Co.) A major Japanese shipmaker has developed a new, highly water-repellent material. When applied to the hull of a boat, this material reduces by half the friction between the boat and the water, leading to a 20% to 30% increase in fuel efficiency. The manufacturer expects to bring the new repellent into use in four or five years.
Like Water off a Duck's Back
When a boat whose hull has been treated with this material moves through the water, however, this friction-reducing layer of air breaks up and is washed away. To prevent this, the company designed a system where an onboard compressor toward the ship's bow constantly delivers air to this pocket, maintaining the layer of air and its friction-reducing properties. The shipmaker calculates that friction between the hull of a standard freighter and the water provides around 60% of the resistance faced by the ship as it sails. If this friction, the greatest source of resistance to the boat, is halved, the overall resistance will drop by 30%, resulting in a matching 30% jump in fuel efficiency. The maker is currently carrying out resistance tests using flat surfaces; it expects to move on to sea testing involving real boats in two to three years. The durability of the material is also being worked on; the company is confident that it can bring it up to a level allowing actual use by the beginning of the new century. The maker also hopes to keep the price of this new material to within 10% to 20% higher than ordinary hull coatings, making it a good choice for the ships of the future.
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