What symbolism is present in The True Confessions of Charlotte Doyle?

The novel The True Confessions of Charlotte Doyle by Avi has several symbols; the following are just a few:  The hurricane that is brewing during the voyage to America is symbolic of what is happening on the ship between Captain Jaggery and his mutinous crew.  The appearance of the round-robin is an item or symbol that the crew is planning a mutiny.  The pants and top that Charlotte wears instead of her dress when she tries to help the crew is the beginning of her transformation and of her new found freedom from being a proper lady.  The clothes are symbolic of the beginning of her change.

How is the mystery of the head revealed in The True Confessions of Charlotte Doyle?

In the dead of night, Charlotte is horrified by what appears to be a grinning head staring at her through the hole above her head. As one might expect, Charlotte's absolutely petrified by this ghoulish apparition and immediately lets out a loud, piercing scream.

With Zachariah's knife in her hand, Charlotte plucks up the courage to investigate. She gingerly approaches the hole from which the head has been grinning at her. As she gets closer, Charlotte can see the head's wicked lips contorted into a devilish smirk. Though terrified, Charlotte still has the courage to stare right back at the head. And as she does so, she realizes that it's not moving.

Inching forward ever so slowly, Charlotte reaches out and touches the head; it feels stiff and unyielding. It then becomes apparent that this is a grotesque carving which appears to have been carved into a large, brown nut. Charlotte reaches out for the carving once more, but as she touches it, it topples over the edge of the hole before crashing to the ground below.