Abstract
Rheological and mechanical comparative tests of the new AquaSun antifouling sol-gel coating coated on shipbuilding steel compared to a commercial silyl acrylate antifouling topcoat containing cuprous oxide and copper pyrithione show further evidence of the practical viability of this multifunctional coating for the protection of the immersed surfaces from biofouling. AquaSun is a less rigid or less viscous material than commercial topcoat, but more adherent to the steel substrate. The reason is linked to its lower viscosity and lower stiffness thanks to which it is able to adapt better to the steel surface through chemical bonds between the silanol groups in the organosilica sol and hydroxyl groups at the surface of steel. These results support further investigation of AquaSun as ecofriendly antifouling paint.



![Author ORCID: We display the ORCID iD icon alongside authors names on our website to acknowledge that the ORCiD has been authenticated when entered by the user. To view the users ORCiD record click the icon. [opens in a new tab]](https://www.cambridge.org/engage/assets/public/coe/logo/orcid.png)