Yes, in early years, asphalt based paint and that was anti-corrosion coat. Problem is that black and red look the same on black and white images. Other thing is the wash out of the coat show about, specific way for anti fouling coats. They work in this way- sea plant attach for the surface and in this case anti fouling. As well this coat include poison, after some time plant die and fall but it also peel of some amount of coat. This is my doubts, what that could be? If this is anti fouling coat, that could be red brown color.