The Adventures of Hotsy Totsy — Clive Cussler

Take a look at Casey and Lacey Nicefolk and you'll see two regular, all-American kids. But these brother-and-sister twins have a secret. Hidden in the family barn is the most magical-and coolest-gadget unknown to man: a mystical box that can turn any small object into a life-size replica.

When the twins' parents go out of town, the two decide to put the box to use. Taking a model boat, they create a fully functioning powerboat and enter a race up the Sacramento River. But this is no ordinary boat, and this is no ordinary race. What follows is a nautical adventure where being the first to cross the finish line is not the only prize.