How does C.S. Forester use imagery in Flying Colours?

Imagery:

Suiting the action to the word the surgeon sniffed at the dressings and at the raw stump.
"Smell, monsieur," he said, holding the dressings to Hornblower's face.

Along its whole length water was brimming over the obstruction; at this particular point it surged over into a wide swirl, sleek at the top, and plunging into foaming chaos below. The boat heaved sickeningly over the summit and went down the slope like a bullet. The steep steady wave at the foot was as unyielding as a brick wall as they crashed into it.