Sentence:  But oh! shipmates! on the starboard hand of every woe, there is a sure delight; and higher the top of that delight, than the bottom of the woe is deep. Is not the main-<WSD>truck</WSD> higher than the kelson is low? 
Meaning of the word marked with <WSD> tags:  (Q13479766)  On a wooden mast, a circular disc (or sometimes a rectangle) of wood near or at the top of the mast, usually with holes or sheaves to reeve signal halyards; also a temporary or emergency place for a lookout. "Main" refers to the mainmast, whereas a "truck" on another mast may be called (on the mizzenmast, for example) "mizzen-truck".