In the words of Mr. Barlow, the Captain had the crew set all the sails
"to put (them) on display. It was to no account. Mocking (them)..."
The Captain is notorious for being a cruel and vindictive leader; he is corrupted by his power. He drives his crew mercilessly - if they are not busy every waking hour, he considers them to be lazy, or "lax." If there is really nothing that needs to be done at any given moment, he invents things for them to do, and the work he comes up with is never easy or quickly completed. Captain Jaggery drives his men constantly, to the point of exhaustion, ostensibly in order to provide needed structure and to keep control. Really, though, he is a bit mad, and he acts this way just because he can.
In Chapter 6, not Chapter 7, Charlotte is on deck with the Captain. He considers the weather for awhile, then tells the second mate, "I believe...we shall soon have a blow." In actuality, there are no indications that this is true, but the mate concurs skeptically, not wanting to disagree; there is no telling what might happen if he angers the unreasonable man. After the crew has slaved to get the sails up and everything else is in place, the Captain appears satisfied, but after all this work, it does not seem that the ship is progressing any more quickly. Even Charlotte perceives the pointlessness of the exercise, observing,
"It was a grand show, but if the ship moved any faster for it, I didn't sense a change" (Chapter 6).