Mr. Horn, who has been working on ships since 1974, spends his free time reading and talking to his family in Arkansas, where few understand the appeal of spending half the year locked away in a tugboat. But he likes it; always has, even back when he had to radio the marine operator in order to call home, or go ashore and wait in line for the pay phone. Over his 38 years on the water, he has read hundreds of books borrowed from the small, tattered floating libraries that accumulate on the tugs.