Using everything from electric motors, balloons, and gears to water jets, steam, chemical reactions, and even gravity, this clever handbook offers a variety of choices for propelling homemade vessels across a pool. Through step-by-step instructions with clear photos, kids will learn how to build more than 20 different model boats for traveling above water and several different submarine projects for traveling below the surface. In addition to the boatbuilding activities included within, young naval architects will find instructions for building an "ocean" to test the boats and a variety of accessories, including four different water pumps, a waterproof battery and motor case, and a working foghorn. Most of the watercrafts are built from recycled and easy-to-find materials, but an appendix also lists local and online sources for wire, plastic propellers, small motors, and more. Do-it-yourselfers and kids with an interest in how things work will find hours of educational entertainment in the projects offered within.