Antifouling coatings are used to improve the speed and energy efficiency of ships by preventing organisms, such as barnacles and weed, building up on the underwater hull and helping the ships movement through the water. Typically, marine coatings are tributyltin self-polishing copolymer paints containing toxic molecules called biocides. They have been the most successful in combating biofouling on ships, but their widespread use has caused severe pollution in the marine ecosystem. The low surface energy marine coating is an entirely non-toxic alternative, which reduces the adhesion strength of marine organisms, facilitating their hydrodynamic removal at high speeds. In this paper, the novel low surface energy non-toxic marine antifouling coatings were prepared with modified acrylic resin, nano-SiO 2 , and other pigments. The effects of nano-SiO 2 on the surface structure and elastic modulus of coating films have been studied, and the seawater test has been carried out in the Dalian Bay. The results showed that micro-nano layered structures on the coating films and the lowest surface energy and elastic modulus could be obtained when an appropriate mass ratio of resin, nano-SiO 2 , and other pigments in coatings approached. The seawater exposure test has shown that the lower the surface energy and elastic modulus of coatings are, the less the marine biofouling adheres on the coating films.non-toxic antifouling coating, low surface energy, elastic modulus, nano-SiO 2 Marine biofouling is caused by the adhesion of barnacles, macroalgae, and microbial slimes. It is a worldwide problem in marine systems. This natural process has heavy negative economic impacts: increase in fuel consumption for ships and in maintenance costs for mariculture equipment's pipes and offshore and harbour constructions. Traditionally, fouling has been controlled by antifouling paint with biocides, such as tributyltin (TBT). TBT is the most toxic of butyltins and has been detected in human food, such as fish. They can accumulate in marine life and be difficult to degrade, which not only causes adverse effects in the environment, but also threatens the health of humans [1][2][3][4][5][6][7] . In humans, TBT residue has been detected in blood [8] . These facts forced the development of national regulations in countries all over the world, i.e., restriction of the use of TBT-containing compounds on vessels less than 25 m in length, restriction of the release rates of TBT-containing compounds from the paints, and elimination of the use of free TBT-holding compounds in paints. Furthermore, after an international convention held on 5 October 2001, parties to the convention have been required to ban the application of TBT-based antifouling paints from 1 January 2003 and the presence of such paints on the surface of the vessel from 1 January 2008 (effective dates) [9] . Low surface energy, non-stick coating is expected to prevent the adhesion of fouling organisms by providing a low-friction, non-wetness surface, on which
