The boat was her lucky charm, her rabbit's foot, her horseshoe, her pot of gold, it was the prize she'd set for herself for leading them from nowhere to somewhere. (1.9)
About that sailboat. If this old clunker doesn't scream symbol to you, we don't know what will. Not only is it Dicey’s lucky charm, it's also her way of sneaking off for a little alone time. Plus, it's what she’s working on when we first meet her. So immediately we connect Dicey to the boat and vice versa:
She stepped into the darkness and placed both her hands flat against the rough hull of the boat. Imagining how it would feel when the little boat rode on the water, how it would respond to the wind in its sails, to the waves sliding by, to her hand on the tiller. She leaned her forehead against the wood, feeling the solid curve of the hull against her skin. Unexpectedly, she found herself yawning, a huge hollow yawn that stretched her diaphragm up against her heart and cracked the hinges of her jaw. (Introduction.5)
Right off the bat, there's a physical, even emotional connection between Dicey and the boat. She leans her head against the boat, exhausted from the long summer of hitchhiking and walking she's just endured, and the boat acts as a kind of comfort for her.
But it's also a sign of her potential. In this moment, the boat can't float. But with a little TLC, which Dicey totally intends to give it: "The boat was back in the barn and she had to begin scraping off the old layers of paint. But not quite yet" (1.20).
The boat, like Dicey, is incomplete. And it can't get itself up to snuff on its own. It needs someone like Dicey to show it a little love, to sand off the old layers of paint and uncover the sea-worthy vessel that's underneath. Dicey, too, can't survive on her own. Throughout the book she learns to accept the help and kindness of others and she and her siblings get back on their feet. As she peels and sands and scrapes each layer of paint off the boat, so she peels back the layers of the Dicey onion, until finally she's comfortable enough to put her whole self out there.
Not to throw down any spoilers or anything, but in the last book of the Tillerman Cycle, Seventeen Against the Dealer, Dicey’s all grown up and owns a boat shop. Perfect, right?