Sentence:  He flung himself at the port ventilator as though he meant to tear it out bodily and toss it overboard. All he did was to move the <WSD>cowl</WSD> round a few inches, with an enormous expenditure of force, and seemed spent in the effort. 
Meaning of the word marked with <WSD> tags:  A ship's ventilator with a bell-shaped top which can be swivelled to catch the wind and force it below.