How does Ernest K. Gann use imagery in Fate is the Hunter?

Examples of Imagery:

"The entire ship shudders in agony, a sensation with is transmitted directly to my bowels."

"As we climb safely over the western hill the tautness leaves Ross's body. He raises a finger to his brow and flicks away invisible sweat. Then he meets my eyes, and the hard muscles about his jaw relax. I can see no anger in his face, not even accusation. Only his breathing, which is still quick, betrays the passing of a crisis."