These almost calligraphic marks on a wash of yellow represent boats on an expanse of sea. A bold brushstroke leaves a faint horizontal line dividing the composition in two, suggesting the distinction between sky and water. In this loose study Turner uses colour and line economically. Shapes, and areas of light and shade, are roughly suggested as he works out the basic compositional structure in preparation for a finished picture. The simple red and black forms suggest light and shade at sunset.
Turner visited Germany on several occasions and toured the tributaries of the Rhine, including the river Mosel. From the town of Coblenz, he painted the majestic peaks of Ehrenbreitstein, a formidable mountain topped by a fortress. He loved to paint the same view at different times of the day, recording the changing light conditions. In his perspective lectures, Turner agreed with Goethes theory that red was an aerial colour, the most commanding of the primaries and the colour of matter itself.
Turner wanted to represent the harmonies of contrasting colours, but he disagreed with the theories of Newton and Goethe. For Turner, their ideas followed the spectrum and primary colour frameworks too rigidly to suggest the diversity of colours and tonal relationships in nature. He experimented with different colour combinations when painting the solid mass of the mountain of Ehrenbreitstein and the hazy atmosphere of the surrounding landscape and the setting sun.