Tom is a cellphone captain and prefers late-model rides with warranty service. If he had a wrench to turn, he admits, there would be few places aboard he could do so effectively. “I’m afraid if something breaks, the best I could do is whack it with a hammer,” he said. He carries one, of course, swimming in the bilge in a rust-filled tool bag with a few petrified hose clamps and impellers. “If the head craps out,” he said, “would you rather have an expert handy or a wrench?” Good point.