We investigate the antimicrobial activity, surface features, wettability and adhesion of photocatalytic xerogel AquaSun deposited on shipbuilding steel, in comparison to those of a commercial antifouling paint. Evaluated exposing the surface of shipbuilding steel pre-treated with primer and tie coat paint, and further coated with a thin layer of AquaSun to a microbial consortium composed by Bacillus aquimaris DSM 16205T and Pseudomonas poae DSM 14936T, the antimicrobial activity is both significant and of broad scope. Taking into account also the low cost, high stability and lack of eco-toxicity of this hybrid sol-gel coating, these results are promising en route to developing novel antimicrobial coatings of broad applicability.