In Sargent's watercolors he often juggles verious techniques to give a painting the feel he wants. At the Boston Fine Arts they described it this way:

"First using pencil sparingly to outline form, he then applied very thin washes of color to damp paper, often scraping out some areas to define forms and suggest texture (here, notice the coils of rope in the immediate foreground [and the way in which he's scraped he surface to bring Venetian Fishing Boatsback highlights of white]. (Boston Fine Arts)

Also notice how his similar treatment of the "floats" that are drying at the bottom of the finishing nets in "Venetian Fishing Boats