you hear holy shit and see the black signalman who is pointing astern at an even bigger wave , maybe 25 feet this time , as it comes out of the dark and you watch that wave catch a smaller wave and build itself up on its back , lifting its head now maybe 35 feet , maybe 40 feet above the ocean surface and see it catch the boat off-rhythm and slam flat against the stern like the back of a hand against the back of a head .