Systems and processes for controlling and/or preventing fouling of marine vessel hulls and fixed structures are disclosed. The systems and processes deliver an anti-fouling composition through a dispersing means, such as dispersion tubing, to the surface of a vessel hull or fixed structure below the water line. Also disclosed are methods of controlling the delivery of an anti-fouling composition to the surface of a vessel hull or fixed structure below the waterline, including the steps of generating signals representative of parameters such as current flow direction and speed and water temperature, to identify and control the proper volume release rate of the anti-fouling solution.